Patent Publication Number: US-8527663-B2

Title: Methods and apparatus for performing non-intrusive network layer performance measurement in communication networks

Description:
FIELD OF THE DISCLOSURE 
     This disclosure relates generally to communication networks and, more particularly, to methods and apparatus for performing non-intrusive network layer performance measurement in communication networks. 
     BACKGROUND 
     Today&#39;s network operators and service providers offer a variety of private network solutions to their customers. Such private networks include, for example, virtual local area networks (VLANs), virtual private networks (VPNs), virtual private LAN service (VPLS) networks, etc. The performance of a particular customer&#39;s private network may need to be measured to ensure the customer obtains a certain level of service guaranteed by, for example, a service level agreement (SLA). Thus, determining accurate network performance measurements is an aspect of providing competitive private network solutions. 
     In conventional private networks, as well as public networks, network performance is typically measured by a standalone testing node or an existing node that is configured to operate in a resident test mode. For example, a separate computer or testing device may be coupled to the network and configured to generate traffic and monitor the resulting network performance. However, such standalone testing nodes can be costly and require separate power sources. In another example, a network node, such as, for example, a router, may be configured to operate in a resident test mode to exchange data with other similarly configured network nodes. However, the resident test modes for network nodes (e.g., such as routers) from different manufacturers may be incompatible. Furthermore, operation in the resident test mode typically requires normal network traffic to be suspended. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of an example communication network including intelligent network interfaces (INIs) and an example data collection facility for performing non-intrusive performance measurements according to the methods and apparatus described herein. 
         FIG. 2  illustrates an example sequence of operations for performing non-intrusive performance measurements in the example communication network of  FIG. 1 . 
         FIG. 3  is a block diagram of an example data link layer INI which may be used to implement the example communication network of  FIG. 1 . 
         FIG. 4  is a block diagram of an example network layer INI which may be used to implement the example communication network of  FIG. 1 . 
         FIG. 5  is a block diagram of an example data collection facility configured to operate on data link layer reporting messages which may be used to implement the example communication network of  FIG. 1 . 
         FIG. 6  is a block diagram of an example data collection facility configured to operate on network layer reporting messages which may be used to implement the example communication network of  FIG. 1 . 
         FIG. 7  is a flowchart representative of example machine readable instructions that may be executed to implement remote INI configuration in the example communication network of  FIG. 1 . 
         FIG. 8A  is a flowchart representative of example machine readable instructions that may be executed to perform measurement test message generation to implement the example data link layer INI of  FIG. 3  and/or the example network layer INI of  FIG. 4 . 
         FIG. 8B  is a flowchart representative of example machine readable instructions that may be executed to perform measurement test message reception to implement the example data link layer INI of  FIG. 3  and/or the example network layer INI of  FIG. 4 . 
         FIG. 9  is a flowchart representative of example machine readable instructions that may be executed to perform reporting message generation to implement the example data link layer INI of  FIG. 3  and/or the example network layer INI of  FIG. 4 . 
         FIG. 10  is a flowchart representative of example machine readable instructions that may be executed to perform report processing to implement the example data collection facilities of  FIGS. 5  and/or  6 . 
         FIG. 11  is a block diagram of an example computer that may execute the example machine readable instructions of  FIGS. 7 ,  8 A- 8 B,  9  and/or  10  to implement the example communication network of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     A block diagram of an example communication network  100  capable of performing non-intrusive performance measurements according to the methods and apparatus described herein is illustrated in  FIG. 1 . The example communication network  100  implements a private network, such as, for example, a virtual local area network (VLAN), a virtual private network (VPN), a virtual private LAN service (VPLS) network, etc. The private network implemented by the example communication network  100  may be used to provide network connectivity between multiple customer networks, such as, for example, the customer networks  110 ,  112  and  114  of the illustrated example. Although the illustrated example depicts the communication network  100  as implementing a private network, the example methods and apparatus disclosed herein are not limited to application only in private networks. For example, the methods and apparatus disclosed herein may be readily adapted for use in any communication network facilitating communication between network nodes/devices. 
     Turning to the illustrated example of  FIG. 1 , the example communication network  100  includes a backbone network  120  to interconnect the example customer networks  110 ,  112  and  114 . The example backbone network  120  may be implemented using any network configured to provide a desired level of connectivity between the customer sites. For example, to provide network layer, also known as layer 3 (L3), connectivity between the example customer networks  110 ,  112  and  114 , the example backbone network  120  may be implemented by, for example, an Internet protocol (IP) based network. In another example, to provide data link layer, also known as layer 2 (L2), connectivity between the example customer networks  110 ,  112  and  114 , the example backbone network  120  may be implemented by, for example, a network implementing multi-protocol label switching (MPLS), a layer 2 tunneling protocol, etc. 
     To couple the example customer networks  110 ,  112  and  114  to the example backbone network  120 , the example communication network  100  includes respective network nodes  130 ,  132  and  134 . The example network nodes  130 ,  132  and  134  may be implemented by any type of network nodes, such as, for example, network routers, bridges, etc., as well as any combination thereof. In the illustrated example, the example network node  130  includes a network access point  140  to couple the example customer network  110  to the example backbone network  120 . Similarly, the example network node  132  includes a network access point  142  and the example network node  134  includes a network access point  144  to couple, respectively, the example customer networks  112  and  114  to the example backbone network  120 . In this way, the network devices included in the example customer networks  110 ,  112  and  114  are able to communicate with each other at the level of connectivity provided by the example backbone network  120 . For example, if the example backbone network  120  provides network layer (L3) connectivity, the network devices included in the example customer networks  110 ,  112  and  114  may communicate with each other using network layer addresses, such as, for example, IP addresses associated with each of the network devices. In another example, if the example backbone network  120  provides data link layer (L2) connectivity, the network devices included in the example customer networks  110 ,  112  and  114  may communicate with each other using data link layer addresses, such as, for example, Ethernet addresses associated with each of the network devices. 
     To perform non-intrusive performance measurements according to the methods and apparatus described herein, the example communication network  100  includes example intelligent network interfaces (INIs)  150 ,  152  and  154 . The example INIs  150 ,  152  and  154  are self-contained devices configured to couple to existing network nodes in the example communication network  100  to exchange test messages for conducting network performance measurements. For example, the INI  150  of the illustrated example is coupled to an available access port  160  of the example network node  130 . Similarly, the example INIs  152  and  154  are coupled, respectively, to available access ports  162  and  164  of the respective example network nodes  132  and  134 . 
     In the illustrated example, some or all of the INIs  150 ,  152  and  154  exchange measurement test messages over the example backbone network  120  to measure network performance between their respective network nodes  130 ,  132  and  134 . The exchange of measurement test messages and resulting network performance measurements are non-intrusive from the perspective that the test messages are generated and received external to the example customer networks  110 ,  112 , and  114  and, thus, do not interfere with or require modification of these networks. Additionally, the exchange of test messages between the INIs  150 ,  152  and  154  does not require configuring any of the network nodes  130 ,  132  and  134  into a resident test mode (which may be substantially incompatible with the resident test mode of another of the network nodes  130 ,  132  and/or  134 ), thereby making network performance measurement non-intrusive from the perspective that the normal operation of the network nodes  130 ,  132  and  134  is not interrupted during the exchange of measurement test messages. For example, test messages may be exchanged between the INIs  150 ,  152  and/or  154  at substantially the same time other network devices (e.g., user devices) coupled to the network nodes  130 ,  132  and/or  134  are exchanging network traffic during normal operation. Furthermore, the example INIs  150 ,  152  and  154  are self-contained and draw power from their respective network access ports  160 ,  162  and  164 , thus are non-intrusive from the perspective of not requiring access to separate power sources in the example communication network  100 . 
     The measurement test messages are exchanged between the example INIs  150 ,  152  and  154  according to the level of connectivity provided by the example backbone network  120 . For example, if the example backbone network  120  provides network layer (L3) connectivity, the INIs  150 ,  152  and  154  may exchange measurement test messages using network layer addresses, such as, for example, IP addresses associated with each of the INIs. In another example, if the example backbone network  120  provides data link layer (L2) connectivity, the INIs  150 ,  152  and  154  may exchange measurement test messages using data link layer addresses, such as, for example, Ethernet addresses associated with each of the INIs. Exchanging of test messages between the INIs  150 ,  152  and  154  in the example communication network  100  is discussed in greater detail below in connection with  FIG. 2 . 
     In addition to being configured to exchange measurement test messages, some or all of the example INIs  150 ,  152  and  154  are configured to send measurement reporting messages to a data collection facility  170  included in the example communication network  100 . The data collection facility  170  of the illustrated example is coupled to the example backbone network  120  to receive the measurement reporting messages from the example INIs  150 ,  152  and/or  154  according to the level of connectivity provided by the example backbone network  120  (e.g., such as via network layer (e.g., IP) addresses in the case of network layer connectivity or via data link layer (e.g., Ethernet) addresses in the case of data link layer connectivity). The data collection facility  170  of the illustrated example processes the received measurement reporting messages to determine and report various network performance measurements. The reception and processing of measurement reporting messages by the example data collection facility  170  in the example communication network  100  is discussed in greater detail below in connection with  FIG. 2 . 
     To configure some or all of the example INIs  150 ,  152  and  154 , the example communication network  100  includes a remote INI configuration terminal  180 . The example remote INI configuration terminal  180  may be implemented using, for example, any workstation, terminal, computing device, etc. The remote INI configuration terminal  180  of the illustrated example is coupled to the example backbone network  120  to send configuration commands to the example INIs  150 ,  152  and/or  154  according to the level of connectivity provided by the example backbone network  120  (e.g., such as via network layer (e.g., IP) addresses in the case of network layer connectivity or via data link layer (e.g., Ethernet) addresses in the case of data link layer connectivity). 
     For example, the remote INI configuration terminal  180  may send configuration commands to some or all of the example INIs  150 ,  152  and  154  to configure the format and/or criteria for exchanging measurement test messages between the INIs, the criteria for sending measurement reporting messages to the example data collection facility  170 , etc. Furthermore, in some example implementations, the example INIs  150 ,  152  and/or  154  can be configured only through commands received via their respective network access ports  160 ,  162  and/or  164  (e.g., such as the configuration commands from the example remote INI configuration terminal  180 ) because, in such implementations, the example INIs  150 ,  152  and/or  154  have no other mechanism for receiving input information other than via the network access ports  160 ,  162  and/or  164 . The sending of configuration commands by the example remote INI configuration terminal  180  to the example INIs  150 ,  152  and  154  in the example communication network  100  is discussed in greater detail below in connection with  FIG. 2 . 
     An example sequence of operations for performing non-intrusive performance measurements in the example communication network  100  of  FIG. 1  is shown in  FIG. 2 . The examples of  FIGS. 1 and 2  include many elements in common. As such, like elements in  FIGS. 1 and 2  are labeled with the same reference numerals. For brevity, the detailed descriptions of these like elements are provided above in connection with the discussion of  FIG. 1  and, therefore, are not repeated in the discussion of  FIG. 2 . 
     Turning to  FIG. 2 , the illustrated example operation of the communication network  110  begins with the example remote INI configuration terminal  180  sending one or more configuration commands (indicated by the circle labeled with a number “ 1 ” in  FIG. 2 ) to configure the example INI  150  to perform network performance measurements in the example communication network  100 . As discussed above, the one or more configuration commands may be sent to the example INI  150  using a network layer (e.g., IP) address and/or a data link layer (e.g., Ethernet) address depending on the level of connectivity provided by the example backbone network  120 . In an example implementation, the remote INI configuration terminal  180  sends configuration commands to the example INI  150  to configure some or all of the following parameters: (1) a destination address of a destination INI with which measurement test messages are to be exchanged, (2) transmission criteria for sending the measurement test messages, (3) format parameters for the test messages, (4) format parameters for measurement test message responses, (5) a destination address of a network device to which measurement reporting messages are to be sent, (6) transmission criteria for sending the measurement reporting messages, etc. 
     For example, depending on the level of connectivity provided by the example backbone network  120 , the destination address configured by the example remote INI configuration terminal  180  for exchanging test messages may be a network layer (e.g., IP) address and/or a data link layer (e.g., Ethernet) address associated with a destination INI. Similarly, depending on the level of connectivity provided by the example backbone network  120 , the destination address configured by the example remote INI configuration terminal  180  for sending measurement reporting messages may be a network layer (e.g., IP) address and/or a data link layer (e.g., Ethernet) address associated with a data collection facility. The transmission criteria configured by the example remote INI configuration terminal  180  may include, for example, a schedule (e.g., periodic or aperiodic) for sending messages, one or more events (such as a full storage buffer) to trigger the sending of messages, etc. The measurement test message format parameters configured by the example remote INI configuration terminal  180  may include, for example, a message payload size, message payload contents (e.g., such as a time stamp), protocol priority/preference information, etc. The measurement test message response format parameters configured by the example remote INI configuration terminal  180  may include, for example, a response payload size, response payload contents (e.g., such as a time stamp), protocol priority/preference information, etc. 
     In the illustrated example, the remote INI configuration terminal  180  sends configuration command(s) to the example INI  150  to configure the destination address for exchanged measurement test messages to be an address (e.g., either network layer or data link layer depending on the connectivity provided by the example backbone network  120 ) of the example INI  152 . The remote INI configuration terminal  180  of the illustrated example also sends configuration command(s) to the example INI  150  to configure the destination address for measurement reporting messages to be an address (e.g., either network layer or data link layer depending on the connectivity provided by the example backbone network  120 ) of the example data collection facility  170 . 
     Next, the example INI  150  exchanges measurement test message(s) (indicated by the circle labeled with a number “ 2 ”) with the example INI  152  according to the transmission criteria previously configured by the example remote INI configuration terminal  180 . For example, the INI  150  generates and sends one or more measurement test messages to the example INI  152  using the destination address (e.g., either network layer or data link layer depending on the connectivity provided by the example backbone network  120 ) previously configured by the example remote INI configuration terminal  180  (e.g., indicated by the circle labeled with a number “ 1 ”). In response, the example INI  152  sends one or more corresponding response messages to the example INI  150  using a response destination address (e.g., either network layer or data link layer depending on the connectivity provided by the example backbone network  120 ) set to be the origination address included in the measurement test message(s) received from the example INI  150  (indicated by the circle labeled with a number “ 2 ”). 
     After exchanging test message(s) with the example INI  152 , the example INI  150  prepares and sends one or more measurement reporting messages (indicated by the circle labeled with a number “ 3 ”) to the example data collection facility  170 . For example, the INI  150  generates and sends the one or more measurement test messages to the example data collection facility  170  using the destination address (e.g., either network layer or data link layer depending on the connectivity provided by the example backbone network  120 ) previously configured by the example remote INI configuration terminal  180  (e.g., indicated by the circle labeled with a number “ 1 ”). In the illustrated example, the INI  150  prepares the measurement reporting messages based on the measurement test messages and corresponding responses previously exchanged with the example INI  152  (e.g., indicated by the circle labeled with a number “ 2 ”). The example INI  150  then sends the prepared measurement reporting messages(s) to the example data collection facility  170  (indicated by the circle labeled with a number “ 3 ”) according to the transmission criteria previously configured by the example remote INI configuration terminal  180  (indicated by the circle labeled with a number “ 1 ”). 
     In response to receiving the measurement reporting message(s) from the example INI  150 , the example data collection facility  170  then processes the received measurement reporting message(s) to determine and report various network performance measurements. For example, in an example implementation in which the example backbone network provides network layer (L3) connectivity, the data collection facility  170  of the illustrated example may determine some or all of the following network performance measurements from the received measurement reporting message(s): (1) network layer packet delay, (2) network layer packet loss, (3) network layer jitter, (4) network layer throughput, etc. In another example implementation in which the example backbone network provides data link layer (L2) connectivity, the data collection facility  170  of the illustrated example may determine some or all of the following network performance measurements from the received measurement reporting message(s): (1) data link layer packet delay, (2) data link layer packet loss, (3) data link layer jitter, (4) data link layer throughput, etc. In either example implementation, the data collection facility  170  of the illustrated example then reports the determined measurements, which may be used, for example, to verify that the example communication network  100  is providing a level of service as guaranteed by a service level agreement (SLA), to debug and/or improve network operation, etc. 
     In the illustrated example, the example INI  152  is configured to also exchange measurement test message(s) with the example INI  154  (e.g., indicated by the circle labeled with a number “ 4 ”), and to send measurement reporting message(s) based on these exchanged test message(s) to the example data collection facility  170  (e.g., indicated by the circle labeled with a number “ 5 ”). Then, as for the reporting messages received from the example INI  150 , the data collection facility  170  of the illustrated example processes the measurement reporting message(s) received from the example INI  152  to determine and report various network performance measurements. Additionally, the example data collection facility  170  may combine measurement reporting messages received from multiple INIs to determine and report other network performance measurements. For example, the data collection facility  170  of the illustrated example may use the measurement reporting messages received from example INI  150  (e.g., indicated by the circle labeled with a number “ 3 ”) to determine the network performance between the example network nodes  130  and  132 , and the measurement reporting messages received from example INI  152  (e.g., indicated by the circle labeled with a number “ 5 ”) to determine the network performance between the example network nodes  132  and  134 . Additionally, the data collection facility  170  of the illustrated example may combine these measurements to determine the overall network performance for traffic routed between the network nodes  130  and  134  but through the network node  132  (e.g., such as when the network node  132  operates as a intermediate node in a multi-hop network). 
     A block diagram of an example data link layer INI  300  which may be used to implement any or all of the example INIs  150 ,  152  and/or  154  of the example communication network  100  of  FIG. 1  is shown in  FIG. 3 . The example data link layer INI  300  is configured to be coupled with a network access port (e.g., such as the network access ports  160 ,  162 ,  164 ) of an existing network node (e.g., such as the network nodes  130 ,  132 ,  134 ) to thereby interface with a communication network (e.g., such as the network  100 ) at a data link layer (L2). As such, the example data link layer INI  300  could be used to implement the example INIs  150 ,  152  and/or  154  in an example implementation of the communication network  100  in which the example backbone network  120  provides data link layer (L2) connectivity. 
     The example INI  300  is a self-contained device for performing non-intrusive network performance measurements according to the methods and apparatus described herein. In particular, the example INI  300  is configured to draw power directly from the network access port with which it is coupled and, thus, does not require a separate power source, power adapter, etc. Additionally, the example INI  300  is further configured to generate test messages autonomously without external intervention and to exchange these test messages with other INIs for conducting network performance measurements. Furthermore, the example INI  300  is configured to generate measurement reporting messages autonomously without external intervention and to send these reporting messages to one or more data collection facilities (e.g., such as the data collection facility  170 ). 
     Turning to  FIG. 3 , the example INI  300  includes a network interface  310  configured to physically couple with a network access port (e.g., such as the network access ports  160 ,  162 ,  164 ) of an existing network node (e.g., such as the network nodes  130 ,  132 ,  134 ). As such, the example network interface  310  provides physical layer, also known as layer 1 (L1), connectivity with the existing network node. In an example implementation, the network interface  310  may be implemented by a registered jack 45 (RJ-45) or similar interface to electrically couple the example INI  310  with the network access port of the existing network node. In another example implementation, the network interface  310  may be implemented by a small form-factor pluggable (SFP) or similar transceiver (e.g., such as a 10 gigabit SFP (XFP) transceiver, a transceiver compliant with the XENPACK standard, etc.) to optically couple the example INI  310  with the network access port of the existing network node. In yet another example implementation, the network interface  310  may be implemented by a gigabit interface converter (GBIC) or similar transceiver to optically couple the example INI  310  with the network access port of the existing network node. 
     To process data sent and received by the example INI  300 , the example INI  300  includes a data link layer (L2) protocol stack  320  interfacing with the example network interface  310 . The data sent by the example INI  300  using the example data link layer (L2) protocol stack  320  includes data packets carrying the measurement test messages to be exchanged with other INI(s), data packets carrying the measurement reporting messages to be sent to one or more data collection facilities, etc. The example data link layer (L2) protocol stack  320  is configured to packetize these measurement test messages and/or measurement reporting messages, and to append the appropriate destination data link layer (L2) address(es) (e.g., such as an Ethernet address) to the resulting data packets for transmission to the appropriate destination device (e.g., such as another INI or a data collection facility). 
     The data received by the example INI  300  using the example data link layer (L2) protocol stack  320  includes data packets carrying the measurement test messages received from other INI(s), data packets carrying configuration commands received from one or more remote INI configuration terminals (e.g., such as the remote INI configuration terminal  180 ), etc. The example data link layer (L2) protocol stack  320  is configured to process the destination data link layer (L2) address(es) (e.g., such as an Ethernet address) included in the received packets carrying such measurement test messages or configuration commands to determine whether the received packets are destined for and should be processed by the example INI  300 . Additionally, the example data link layer (L2) protocol stack  320  may process the origination data link layer (L2) address(es) (e.g., such as an Ethernet address) included in the received packets to determine the INI(s) to which corresponding measurement test message response(s) should be sent. 
     The example INI  300  also includes a configuration management unit  330  to process configuration commands carried by the data packets received and processed by the example data link layer (L2) protocol stack  320 . As discussed above, the configuration commands processed by the example configuration management unit  330  may configure any or all of the following parameters: (1) a destination address of a destination INI with which measurement test messages are to be exchanged, (2) transmission criteria for sending the measurement test messages, (3) format parameters for the test messages, (4) format parameters for measurement test message responses, (5) a destination address of a network device to which measurement reporting messages are to be sent, (6) transmission criteria for sending the measurement reporting messages, etc. In the illustrated example, the resulting parameters configured by the configuration management unit  330  are stored in a storage unit  340 , which may be implemented by any type of storage element, memory device, etc. 
     To perform measurement test message processing, the example INI  300  includes a test message processor  350  which interfaces with the example data link layer (L2) protocol stack  320 . For example, the test message processor  350  may generate measurement test messages to be exchanged with destination INI(s) using the parameters stored in the example storage unit  340  (e.g., the configured format, destination address, transmission criteria, etc.). Additionally, the example test message processor  350  may receive measurement test messages from other originating INIs, and generate appropriate measurement test message responses using the configured format, etc., parameters stored in the example storage unit  340 . Furthermore, the example test message processor  350  may store its generated measurement test messages and corresponding received responses in the example storage unit  340  for use in subsequent measurement reporting. 
     The example INI  300  also includes a reporting message processor  360  to generate and send measurement reporting messages to be carried by the data packets processed and sent by the example data link layer (L2) protocol stack  320 . For example, the reporting message processor  360  may prepare measurement reporting messages to report the contents of the generated measurement test messages and corresponding responses stored in the example storage unit  340 . Then, the example reporting message processor  360  may generate measurement reporting messages to be sent to one or more data collection facilities using the configured format, destination address, transmission criteria, etc., parameters stored in the example storage unit  340 . 
     The example INI  300  further includes a power management unit  370  to provide power to the components, devices, circuitry, etc., implementing the example INI  300 . For example, the power management unit  370  may provide power to any or all of the example network interface  310 , the example data link layer (L2) protocol stack  320 , the example configuration management unit  330 , the example storage unit  340 , the example test message processor  350  and/or the example reporting message processor  360 . In the illustrated example, the power management unit  370  interfaces with the example network interface  310  to obtain its source power directly from the network access port with which the example INI  300  is coupled. The example power management unit  370  then regulates, conditions, etc., the source power obtained directly from the network access port to provide the appropriate power signals to the components, devices, circuitry, etc., implementing the example INI  300 . 
     A block diagram of an example network layer INI  400  which may be used to implement any or all of the example INIs  150 ,  152  and/or  154  of the example communication network  100  of  FIG. 1  is shown in  FIG. 4 . The example network layer INI  400  is configured to be coupled with a network access port (e.g., such as the network access ports  160 ,  162 ,  164 ) of an existing network node (e.g., such as the network nodes  130 ,  132 ,  134 ) to thereby interface with a communication network (e.g., such as the network  100 ) at a network layer (L3). As such, the example network layer INI  400  could be used to implement the example INIs  150 ,  152  and/or  154  in an example implementation of the communication network  100  in which the example backbone network  120  provides network layer (L3) connectivity. 
     The example INI  400 , like the example INI  300  of  FIG. 3 , is a self-contained device for performing non-intrusive network performance measurements according to the methods and apparatus described herein. In particular, the example INI  400  is configured to draw power directly from the network access port with which it is coupled and, thus, does not require a separate power source, power adapter, etc. Additionally, the example INI  400  is further configured to generate test messages autonomously without external intervention and to exchange these test messages with other INIs for conducting network performance measurements. Furthermore, the example INI  400  is configured to generate measurement reporting messages autonomously without external intervention and to send these reporting messages to one or more data collection facilities (e.g., such as the data collection facility  170 ). 
     The example INI  400  of  FIG. 4  includes many elements in common with the example INI  300  of  FIG. 3 . As such, like elements in  FIGS. 3 and 4  are labeled with the same reference numerals. For brevity, the detailed descriptions of these like elements are provided above in connection with the discussion of  FIG. 3  and, therefore, are not repeated in the discussion of  FIG. 4 . 
     Turning to  FIG. 4 , the example INI  400  includes the example network interface  310 , the example data link layer (L2) protocol stack  320 , the example configuration management unit  330 , the example storage unit  340 , the example test message processor  350 , the example reporting message processor  360  and the example power management unit  370  described in detail above in connection with  FIG. 3 . Additionally, the example INI  400  includes a network layer (L3) protocol stack  410  interfacing with the example data link layer (L2) protocol stack  320 . 
     In the illustrated example, the network layer (L3) protocol stack  410  processes data to be sent by the example INI  400 . The data sent by the example INI  400  carries the measurement test messages to be exchanged with other INI(s), the measurement reporting messages to be sent to one or more data collection facilities, etc., as discussed above. The example network layer (L3) protocol stack  410  is configured to packetize these measurement test messages and/or measurement reporting messages, and to include the appropriate destination network layer (L3) address(es) (e.g., such as an Ethernet address) in the resulting network layer data packets. The example network layer (L3) protocol stack  410  then provides the prepared network layer data packets to the example data link layer (L2) protocol stack  320  for packetizing into corresponding data link layer data packets for transmission to the appropriate destination device (e.g., such as another INI or a data collection facility). 
     In the illustrated example, the network layer (L3) protocol stack  410  also processes data received by the example INI  400 . The data received by the example INI  400  includes data packets carrying the measurement test messages received from other INI(s), the configuration commands received from one or more remote INI configuration terminals (e.g., such as the remote INI configuration terminal  180 , etc., as discussed above. The example data network layer (L3) protocol stack  410  is configured to process the destination network layer (L3) address(es) (e.g., such as an IP address) included in the network layer packets output from the example data link layer (L2) protocol stack  320  after it processes the corresponding data link layer packets received via the example network interface  310 . The example data network layer (L3) protocol stack  410  uses the processed network layer address(es) to determine whether the received network layer packets carrying the received measurement test messages or configuration commands, etc., are destined for and should be processed by the example INI  400 . Additionally, the example network layer (L3) protocol stack  410  may process the origination network layer (L3) address(es) (e.g., such as an IP address) included in the network layer packets output from the example data link layer (L2) protocol stack  320  to determine the INI(s) to which corresponding measurement test message response(s) should be sent. 
     In some example implementations, the INI  300  of  FIG. 3  and/or the INI  400  of  FIG. 4  may include an external interface (not shown) to enable local device configuration and/or local reporting of measurement reporting messages. Such an external interface could be implemented by any appropriate interface, such as, for example, a serial port, a universal serial bus (USB), a Bluetooth interface, an infrared (IR) interface, etc. 
     A block diagram of a first example data collection facility  500  which may be used to implement the example data collection facility  170  of the example communication network  100  of  FIG. 1  is shown  FIG. 5 . The first example data collection facility  500  is configured to operate on data link layer reporting messages received via a backbone network (e.g., such as the example backbone network  120 ) providing data link layer (L2) connectivity. Turning to  FIG. 5 , the example data collection facility  500  includes a network interface  510  configured to physically couple with a backbone network (e.g., such as the example backbone network  120 ). As such, the example network interface  510  provides physical layer (L1) connectivity with the backbone network. In an example implementation, the network interface  510  may be implemented by an RJ-45 or similar interface to electrically couple the example data collection facility  500  with the backbone network. In another example implementation, the network interface  510  may be implemented by an SFP or similar transceiver (e.g., such as an XFP transceiver, a transceiver compliant with the XENPACK standard, etc.) to optically couple the example data collection facility  500  with the backbone network. In yet another example implementation, the network interface  510  may be implemented by a GBIC or similar transceiver to optically couple the example data collection facility  500  with the backbone network. 
     To process data received by the example data collection facility  500 , the example data collection facility  500  includes a data link layer (L2) protocol stack  520  interfacing with the example network interface  510 . The data received by the example data collection facility  500  using the example data link layer (L2) protocol stack  520  includes, for example, data packets carrying the measurement reporting messages received from one or more INIs implementing non-intrusive network performance monitoring. The example data link layer (L2) protocol stack  520  is configured to process the destination data link layer (L2) address(es) (e.g., such as an Ethernet address) included in the received packets carrying such measurement reporting messages to determine whether the received packets are destined for and should be processed by the example data collection facility  500 . Additionally, the example data link layer (L2) protocol stack  520  may process the origination data link layer (L2) address(es) (e.g., such as an Ethernet address) included in the received packets to associate the received measurement reporting message(s) with the appropriate originating INI(s). 
     The example data collection facility  500  also includes a measurement reporting processor  530  to process the measurement reporting messages received via the example data link layer (L2) protocol stack  520 . For example, and as discussed above, because the measurement reporting messages are received via a network providing data link layer (L2) connectivity, the example measurement reporting processor  530  may determine some or all of the following network performance measurements from the received measurement reporting message(s): (1) data link layer packet delay, (2) data link layer packet loss, (3) data link layer jitter, (4) data link layer throughput, etc. Additionally, and as discussed above, the example measurement reporting processor  530  may combine measurement reporting messages received from multiple INIs to determine and report other (e.g., more complex) network performance measurements (e.g., such as data link layer performance measurements associated with multi-hop network topologies). 
     To report the network performance measurements determined by the example measurement reporting processor  530 , the example data collection facility  500  further includes an example report generator  540 . In the illustrated example, the report generator  540  is configured to generate one or more reports from the determined network performance measurements which may be used, for example, to verify that the network whose performance is being measured is providing a level of service guaranteed by, for example, a service level agreement (SLA). Additionally or alternatively, the report(s) generated by the example report generator  540  may be used to debug and/or improve network operation, and/or for any other purpose in which having network performance measurements may prove beneficial. 
     A block diagram of a second example data collection facility  600  which may be used to implement the example data collection facility  170  of the example communication network  100  of  FIG. 1  is shown  FIG. 6 . The second example data collection facility  600  is configured to operate on network layer reporting messages received via a backbone network (e.g., such as the example backbone network  120 ) providing network layer (L3) connectivity. The example data collection facility  600  of  FIG. 6  includes many elements in common with the example data collection facility  500  of  FIG. 5 . As such, like elements in  FIGS. 5 and 6  are labeled with the same reference numerals. For brevity, the detailed descriptions of these like elements are provided above in connection with the discussion of  FIG. 5  and, therefore, are not repeated in the discussion of  FIG. 6 . 
     Turning to  FIG. 6 , the example data collection facility  600  includes the example network interface  510 , the example data link layer (L2) protocol stack  520  and the example report generator  540  described in detail above in connection with  FIG. 5 . Additionally, the example data collection facility  600  includes a network layer (L3) protocol stack  610  interfacing with the example data link layer (L2) protocol stack  520  to process data received by the example data collection facility  600 . 
     The data received by the example data collection facility  600  using the example network layer (L3) protocol stack  610  includes, for example, data packets carrying the measurement reporting messages received from one or more INIs implementing non-intrusive network performance monitoring. The example network layer (L3) protocol stack  610  is configured to process the destination network layer (L3) address(es) (e.g., such as an IP address) included in the network layer packets output from the example data link layer (L2) protocol stack  520  after it processes the corresponding data link layer packets received via the example network interface  510 . The example network layer (L3) protocol stack  610  uses the processed network layer address(es) to determine whether the network layer packets carrying the received measurement reporting messages are destined for and should be processed by the example data collection facility  600 . Additionally, the example network layer (L3) protocol stack  610  may process the origination network layer (L3) address(es) (e.g., such as an IP address) included in the received packets to associate the received measurement reporting message(s) with the appropriate originating INI(s). 
     The example data collection facility  600  also includes a measurement reporting processor  620  to process the measurement reporting messages received via the example network layer (L3) protocol stack  610 . For example, and as discussed above, because the measurement reporting messages are received via a network providing network layer (L3) connectivity, the example measurement reporting processor  620  may determine some or all of the following network performance measurements from the received measurement reporting message(s): (1) network layer packet delay, (2) network layer packet loss, (3) network layer jitter, (4) network layer throughput, etc. Additionally, and as discussed above, the example measurement reporting processor  620  may combine measurement reporting messages received from multiple INIs to determine and report other (e.g., more complex) network performance measurements (e.g., such as network layer performance measurements associated with multi-hop network topologies). 
     Flowcharts representative of example machine readable instructions that may be executed to implement any, all, or portions of the example communication network  100 , the example INIs  150 ,  152 ,  154 ,  300  and/or  400 , the example data collection facilities  170 ,  500  and/or  600 , the example remote INI configuration terminal  180 , the example network interface  310 , the example data link layer (L2) protocol stack  320 , the example configuration management unit  330 , the example test message processor  350 , the example reporting message processor  360 , the example network layer (L3) protocol stack  410 , the example network interface  510 , the example data link layer (L2) protocol stack  520 , the example measurement reporting processor  530 , the example report generator  540 , the example network layer (L3) protocol stack  610  and/or the example measurement reporting processor  620  are shown in  FIGS. 7 ,  8 A- 8 B,  9  and  10 . In these examples, the machine readable instructions represented by each flowchart may comprise one or more programs for execution by: (a) a processor, such as the processor  1112  shown in the example computer  1100  discussed below in connection with  FIG. 11 , (b) a controller, and/or (c) any other suitable device. The one or more programs may be embodied in software stored on a tangible medium such as, for example, a flash memory, a CD-ROM, a floppy disk, a hard drive, a DVD, or a memory associated with the processor  1112 , but the entire program or programs and/or portions thereof could alternatively be executed by a device other than the processor  1112  and/or embodied in firmware or dedicated hardware (e.g., implemented by an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable logic device (FPLD), discrete logic, etc.). For example, any or all of the example communication network  100 , the example INIs  150 ,  152 ,  154 ,  300  and/or  400 , the example data collection facilities  170 ,  500  and/or  600 , the example remote INI configuration terminal  180 , the example network interface  310 , the example data link layer (L2) protocol stack  320 , the example configuration management unit  330 , the example test message processor  350 , the example reporting message processor  360 , the example network layer (L3) protocol stack  410 , the example network interface  510 , the example data link layer (L2) protocol stack  520 , the example measurement reporting processor  530 , the example report generator  540 , the example network layer (L3) protocol stack  610  and/or the example measurement reporting processor  620  could be implemented by any combination of software, hardware, and/or firmware. Also, some or all of the machine readable instructions represented by the flowchart of  FIGS. 7 ,  8 A- 8 B,  9  and  10  may be implemented manually. Further, although the example machine readable instructions are described with reference to the flowcharts illustrated in  FIGS. 7 ,  8 A- 8 B,  9  and  10 , many other techniques for implementing the example methods and apparatus described herein may alternatively be used. For example, with reference to the flowcharts illustrated in  FIGS. 7 ,  8 A- 8 B,  9  and  10 , the order of execution of the blocks may be changed, and/or some of the blocks described may be changed, eliminated, combined and/or subdivided into multiple blocks. 
     Example machine readable instructions  700  that may be executed to implement remote INI configuration in the example communication network  100  of  FIG. 1  are shown in  FIG. 7 . For example, the machine readable instructions  700  may be executed by the example remote INI configuration terminal  180  to configure any or all of the example INIs  150 ,  152  and/or  154  in the example communication network  100 . Without loss of generality, and for ease of discussion, execution of the example machine readable instructions  700  is described with reference to the configuration of the example INI  150  by the example remote INI configuration terminal  180 . 
     Turning to  FIG. 7 , the example machine readable instructions  700  begin execution at block  705  at which the example remote INI configuration terminal  180  determines whether the example INI  150  is available for configuration. For example, at block  705  the example remote INI configuration terminal  180  may receive one or more heartbeats or other initialization messages which the example INI  150  is configured to send after being coupled to the network access port  160  of the existing network node  130 . Additionally or alternatively, at block  705  an operator of the example remote INI configuration terminal  180  may manually indicate via one or more input commands that the example INI  150  is available for configuration. 
     After determining that the example INI  150  is available for configuration at block  705 , control proceeds to block  710  at which the example remote INI configuration terminal  180  opens a configuration session with the example INI  150 . In an example implementation in which the communication network  100  provides data link layer (L2) connectivity, at block  710  the example remote INI configuration terminal  180  may send one or more session initiation commands over the network  100  to the example INI  150  using a data link layer (L2) address (e.g., such as an Ethernet address) associated with the example INI  150 . In another example implementation in which the communication network  100  provides network layer (L3) connectivity, at block  710  the example remote INI configuration terminal  180  may send one or more session initiation commands over the network  100  to the example INI  150  using a network layer (L3) address (e.g., such as an IP address) associated with the example INI  150 . 
     After opening the configuration session at block  710 , control proceeds to block  715  at which the example remote INI configuration terminal  180  configures one or more destination addresses (e.g., data link layer and/or network layer addresses) associated with one or more destination INIs (e.g., such as the example INIs  152  and/or  154 ) with which measurement test messages are to be exchanged. In an example implementation in which the communication network  100  provides data link layer (L2) connectivity, at block  715  the example remote INI configuration terminal  180  may send one or more test message destination address configuration commands over the network  100  to the example INI  150  using a data link layer (L2) address (e.g., such as an Ethernet address) associated with the example INI  150 . In another example implementation in which the communication network  100  provides network layer (L3) connectivity, at block  715  the example remote INI configuration terminal  180  may send one or more test message destination address configuration commands over the network  100  to the example INI  150  using a network layer (L3) address (e.g., such as an IP address) associated with the example INI  150 . 
     After configuring the one or more destination addresses at block  715 , control proceeds to block  720  at which the example remote INI configuration terminal  180  configures the criteria for the example INI  150  to send measurement test messages to the one or more destination INIs. The test message transmission criteria configured at block  720  may include, for example, a transmission schedule, a periodic or aperiodic transmission cycle, a transmission event (e.g., such as a storage full event or other trigger), etc. In an example implementation in which the communication network  100  provides data link layer (L2) connectivity, at block  720  the example remote INI configuration terminal  180  may send one or more test message transmission criteria configuration commands over the network  100  to the example INI  150  using a data link layer (L2) address (e.g., such as an Ethernet address) associated with the example INI  150 . In another example implementation in which the communication network  100  provides network layer (L3) connectivity, at block  720  the example remote INI configuration terminal  180  may send one or more test message transmission criteria configuration commands over the network  100  to the example INI  150  using a network layer (L3) address (e.g., such as an IP address) associated with the example INI  150 . 
     After configuring the test message criteria at block  720 , control proceeds to block  725  at which the example remote INI configuration terminal  180  configures the format for measurement test message(s) (and possibly responses) to be sent by the example INI  150 . The measurement test message format parameters configured at block  725  may include, for example, a message payload size, message payload contents (e.g., such as a time stamp), protocol priority/preference information, etc. In an example implementation in which the communication network  100  provides data link layer (L2) connectivity, at block  725  the example remote INI configuration terminal  180  may send one or more test message format configuration commands over the network  100  to the example INI  150  using a data link layer (L2) address (e.g., such as an Ethernet address) associated with the example INI  150 . In another example implementation in which the communication network  100  provides network layer (L3) connectivity, at block  725  the example remote INI configuration terminal  180  may send one or more test message format configuration commands over the network  100  to the example INI  150  using a network layer (L3) address (e.g., such as an IP address) associated with the example INI  150 . 
     After configuring the measurement test message format at block  725 , control proceeds to block  730  at which the example remote INI configuration terminal  180  configures one or more destination addresses (e.g., data link layer and/or network layer addresses) associated with one or more data collection facilities (e.g., such as the example data collection facility  170 ) to which measurement reporting messages are to be sent. In an example implementation in which the communication network  100  provides data link layer (L2) connectivity, at block  730  the example remote INI configuration terminal  180  may send one or more reporting message destination address configuration commands over the network  100  to the example INI  150  using a data link layer (L2) address (e.g., such as an Ethernet address) associated with the example INI  150 . In another example implementation in which the communication network  100  provides network layer (L3) connectivity, at block  730  the example remote INI configuration terminal  180  may send one or more reporting message destination address configuration commands over the network  100  to the example INI  150  using a network layer (L3) address (e.g., such as an IP address) associated with the example INI  150 . 
     After configuring the one or more destination addresses at block  730 , control proceeds to block  735  at which the example remote INI configuration terminal  180  configures the criteria for the example INI  150  to send measurement reporting messages to the one or more data collection facilities. The reporting message transmission criteria configured at block  720  may include, for example, a transmission schedule, a periodic or aperiodic transmission cycle, a transmission event (e.g., such as a storage full event or other trigger), etc. In an example implementation in which the communication network  100  provides data link layer (L2) connectivity, at block  735  the example remote INI configuration terminal  180  may send one or more reporting message transmission criteria configuration commands over the network  100  to the example INI  150  using a data link layer (L2) address (e.g., such as an Ethernet address) associated with the example INI  150 . In another example implementation in which the communication network  100  provides network layer (L3) connectivity, at block  735  the example remote INI configuration terminal  180  may send one or more reporting message transmission criteria configuration commands over the network  100  to the example INI  150  using a network layer (L3) address (e.g., such as an IP address) associated with the example INI  150 . 
     Next, control proceeds to block  740  at which the example remote INI configuration terminal  180  closes the configuration session established with the example INI  150  at block  710 . In an example implementation in which the communication network  100  provides data link layer (L2) connectivity, at block  740  the example remote INI configuration terminal  180  may send one or more session termination commands over the network  100  to the example INI  150  using a data link layer (L2) address (e.g., such as an Ethernet address) associated with the example INI  150 . In another example implementation in which the communication network  100  provides network layer (L3) connectivity, at block  740  the example remote INI configuration terminal  180  may send one or more session termination commands over the network  100  to the example INI  150  using a network layer (L3) address (e.g., such as an IP address) associated with the example INI  150 . Execution of the example machine readable instructions  700  then ends. 
     Example machine readable instructions  800  that may be executed to implement measurement test message generation processing in one or more of the example INIs  150 ,  152  and/or  154  of the example communication network  100  of  FIG. 1 , in the example INI  300  of  FIG. 3  and/or the example INI  400  of  FIG. 4  are shown in  FIG. 8A . The example machine readable instructions  800  may be executed periodically or aperiodically, according to a schedule, upon occurrence of an event, etc. Without loss of generality, and for ease of discussion, execution of the example machine readable instructions  800  is described with reference to the example INI  150  operating in the example communication network  100 . 
     Turning to  FIG. 8A , the example machine readable instructions  800  begin execution at block  805  at which the example INI  150  formats a measurement test message to be sent to a destination INI (e.g., such as the example INI  152  or  154 ). For example, at block  805  the example INI may format the payload size, message payload contents (e.g., such as a time stamp), protocol priority/preference information, etc. of the measurement test message based on parameters configured by the example remote INI configuration terminal  180  and/or via execution of the example machine readable instructions  700  of  FIG. 7 . Additionally, in an example implementation in which the communication network  100  provides data link layer (L2) connectivity, at block  805  the example INI formats the measurement test message to include a data link layer (L2) address (e.g., such as an Ethernet address) associated with the destination INI. Additionally or alternatively, in an example implementation in which the communication network  100  provides network layer (L3) connectivity, at block  805  the example INI formats the measurement test message to include a network layer (L3) address (e.g., such as an IP address) associated with the destination INI. 
     After formatting the measurement test message at block  805 , control proceeds to block  810  at which the example INI  150  sends the measurement test message to the destination INI according to its configured test message transmission criteria. For example, at block  810  the example INI  150  may send the measurement test message to the destination INI based on one or more of a transmission schedule, a periodic or aperiodic transmission cycle, a transmission event (e.g., such as a storage full event or other trigger), etc., configured by the example remote INI configuration terminal  180  and/or via execution of the example machine readable instructions  700  of  FIG. 7 . The measurement test message is sent to the destination INI at block  810  using the destination INI&#39;s data link layer (L2) and/or network layer (L3) address as appropriate depending on the connectivity provided by the example communication network  100 . 
     After the measurement test message is sent at block  810 , control proceeds to block  815  at which the example INI  150  waits for a response from the destination INI. If a response is not received (block  820 ), control proceeds to block  825  at which the example INI  150  determines whether a timeout period has expired. If the timeout period has not expired (block  825 ), control returns to block  820  at which the example INI  150  continues to wait for the response from the destination INI. However, if the timeout period has expired (block  825 ), control proceeds to block  830  at which the example INI  150  determines and indicates that a response to the measurement test message sent at block  810  was not received from the destination INI. 
     Returning to block  820 , if a response was received from the destination INI, or if the example INI  150  indicates that no response was received due to expiration of a timeout period (block  830 ), control proceeds to block  835 . At block  835 , the example INI  150  stores the measurement test messages sent at block  810  and the corresponding received response for use in subsequent measurement reporting. The received response stored at block  835  may correspond to the contents of an actual response from the destination INI (e.g., if one is received) or an indication that no response was received (e.g., if the timeout period expired). 
     Next, control proceeds to block  840  at which the example INI  150  determines whether measurement test message generation is complete. For example, the INI  150  could be configured by the example remote INI configuration terminal  180  to send a finite number (e.g., batch) of measurement test messages to one or more destination INIs. If measurement test message generation is not complete (block  840 ), control returns to block  805  and blocks subsequent thereto at which the example INI  150  generates the next measurement test message to be sent. If, however, measurement test message generation is complete (block  840 ), execution of the example machine readable instructions  800  ends. As an alternative to the processing performed at block  840 , control could automatically loop back to block  805  to allow test message generation to continue indefinitely, or at least until the example INI  150  is decoupled from the network access port  160  of the existing network node  130 . 
     Example machine readable instructions  850  that may be executed to implement measurement test message reception processing in one or more of the example INIs  150 ,  152  and/or  154  of the example communication network  100  of  FIG. 1 , in the example INI  300  of  FIG. 3  and/or the example INI  400  of  FIG. 4  are shown in  FIG. 8B . The example machine readable instructions  850  may be executed continuously, during a specified (e.g., configured) interval of time, etc. Additionally, in some example implementations the example machine readable instructions  800  and  850  of  FIGS. 8A and 8B , respectively, are executed in parallel to allow simultaneous transmission and reception of measurement test messages. Without loss of generality, and for ease of discussion, execution of the example machine readable instructions  850  is described with reference to the example INI  150  operating in the example communication network  100 . 
     Turning to  FIG. 8B , the example machine readable instructions  850  begin execution at block  855  at which the example INI  150  waits to receive a measurement test message from an originating INI (e.g., such as the example INI  152  or  154 ). If a measurement test message is not received (block  860 ), control returns to block  855  at which the example INI continues to wait to receive a measurement test message. However, if a measurement test message is received (block  860 ), control proceeds to block  865  at which the example INI  150  formats a response to the received measurement test message. For example, at block  865  the example INI may format the payload size, message payload contents (e.g., such as a time stamp), protocol priority/preference information, etc. of the response based on parameters configured by the example remote INI configuration terminal  180  and/or via execution of the example machine readable instructions  700  of  FIG. 7 . Additionally, in an example implementation in which the communication network  100  provides data link layer (L2) connectivity, at block  865  the example INI formats the response to include a data link layer (L2) address (e.g., such as an Ethernet address) associated with the originating INI (e.g., and obtained from the received measurement test message). Additionally or alternatively, in an example implementation in which the communication network  100  provides network layer (L3) connectivity, at block  865  the example INI formats the measurement test message to include a network layer (L3) address (e.g., such as an IP address) associated with the originating INI (e.g., and obtained from the received measurement test message). 
     After formatting the response at block  865 , control proceeds to block  870  at which the example INI  150  sends the response to the originating INI corresponding to the received measurement test message. The response is sent to the originating INI at block  870  using the originating INI&#39;s data link layer (L2) or network layer (L3) address as appropriate depending on the connectivity provided by the example communication network  100 . 
     Next, control proceeds to block  875  at which the example INI  150  determines whether measurement test message reception is complete. For example, the INI  150  could be configured by the example remote INI configuration terminal  180  to receive a finite number (e.g., batch) of measurement test messages, to perform reception during a finite interval of time, etc. If measurement test message generation is not complete (block  875 ), control returns to block  855  and blocks subsequent thereto at which the example INI  150  waits to receive the next measurement test message. If, however, measurement test message reception is complete (block  875 ), execution of the example machine readable instructions  850  ends. As an alternative to the processing performed at block  875 , control could automatically loop back to block  855  to allow test message reception to continue indefinitely, or at least until the example INI  150  is decoupled from the network access port  160  of the existing network node  130 . 
     Example machine readable instructions  900  that may be executed to implement measurement reporting message processing in one or more of the example INIs  150 ,  152  and/or  154  of the example communication network  100  of  FIG. 1 , in the example INI  300  of  FIG. 3  and/or the example INI  400  of  FIG. 4  are shown in  FIG. 9 . The example machine readable instructions  900  may be executed periodically or aperiodically, according to a schedule, upon occurrence of an event, etc. Without loss of generality, and for ease of discussion, execution of the example machine readable instructions  900  is described with reference to the example INI  150  operating in the example communication network  100 . 
     Turning to  FIG. 9 , the example machine readable instructions  900  begin execution at block  905  at which the example INI  150  detects one or more criteria causing reporting message processing to be initiated. The criteria detected at block  905  may include, for example, occurrence of a transmission time corresponding to a specified transmission schedule, a periodic or aperiodic transmission cycle, etc., and/or occurrence of a transmission event (e.g., such as storage full event or other trigger). The transmission schedule, the periodic or aperiodic transmission cycle, the transmission event, etc., may be configured by the example remote INI configuration terminal  180  and/or via execution of the example machine readable instructions  700  of  FIG. 7 . 
     Next, control proceeds to block  910  at which the example INI  150  retrieves one or more measurement test messages and a corresponding one or more responses from storage (e.g., such as the example storage unit  340  of  FIGS. 3  and/or  4 ). Alternatively, at block  910  the example INI  150  may retrieve the contents (or selected portions thereof) of the one or more measurement test messages and the corresponding one or more responses from storage. 
     Next, control proceeds to block  915  at which the example INI  150  formats one or more measurement reporting messages to be sent to a data collection facility (e.g., such as the data collection facility  170 ). For example, at block  915  the example INI may format the contents (or selected portions thereof) of the one or more retrieved measurement test messages and the corresponding one or more retrieved responses into one or more fields of the measurement reporting message(s). Additionally, at block  915  the example INI  150  includes an appropriate address for the destination data collection facility in the example measurement reporting message(s) as configured by the example remote INI configuration terminal  180  and/or via execution of the example machine readable instructions  700  of  FIG. 7 . For example, in an implementation in which the communication network  100  provides data link layer (L2) connectivity, at block  915  the example INI formats the measurement reporting message(s) to include a data link layer (L2) address (e.g., such as an Ethernet address) associated with the destination data collection facility. Additionally or alternatively, in an example implementation in which the communication network  100  provides network layer (L3) connectivity, at block  915  the example INI formats the measurement reporting message(s) to include a network layer (L3) address (e.g., such as an IP address) associated with the destination data collection facility. 
     After formatting the measurement reporting message(s) at block  915 , control proceeds to block  920  at which the example INI  150  sends the measurement reporting message(s) to the destination data collection facility. The measurement reporting message(s) sent to the destination data collection facility at block  920  uses/(use) the destination data collection facility&#39;s data link layer (L2) and/or network layer (L3) address as appropriate depending on the connectivity provided by the example communication network  100 . After sending the measurement reporting message(s) at block  920 , execution of the example machine readable instructions  900  ends. 
     Example machine readable instructions  1000  that may be executed to implement measurement report processing in the example data collection facility  170  of  FIG. 1 , the example data collection facility  500  of  FIG. 5  and/or the example data collection facility  600  of  FIG. 6  are shown in  FIG. 10 . The example machine readable instructions  1000  may be executed continuously, during a specified (configured) interval of time, etc. Without loss of generality, and for ease of discussion, execution of the example machine readable instructions  1000  is described with reference to the example data collection facility  170  operating in the example communication network  100 . 
     Turning to  FIG. 10 , the example machine readable instructions  1000  begin execution at block  1005  at which the example data collection facility  170  receives one or more reporting messages from one or more INIs (e.g., such as the INIs  150 ,  152  and/or  154 ) operating in the example communication network  100 . Additionally, at block  1005  the example data collection facility  170  may process the origination address(es) (e.g., data link layer (L2) and/or network layer (L3) address(es)) included in the received message(s) to associate the received measurement reporting message(s) with the appropriate originating INI(s). Next, control proceeds to block  1010  at which the example data collection facility  170  processes the measurement reporting message(s) received at block  1005  to determine network performance in the form of one or more determined network performance measurements. 
     In an example implementation in which the received measurement reporting messages correspond to a network (e.g., the communication network  100 ) providing data link layer (L2) connectivity, at block  1010  the example data collection facility  170  may determine some or all of the following network performance measurements from the received measurement reporting message(s): (1) data link layer packet delay, (2) data link layer packet loss, (3) data link layer jitter, (4) data link layer throughput, etc. Additionally, and as discussed above, at block  1010  the example data collection facility  170  may combine measurement reporting messages received from multiple INIs to determine and report other (e.g., more complex) network performance measurements (e.g., such as data link layer performance measurements associated with multi-hop network topologies). 
     In another example implementation in which the received measurement reporting messages correspond to a network (e.g., the communication network  100 ) providing network layer (L3) connectivity, at block  1010  the example data collection facility  170  may determine some or all of the following network performance measurements from the received measurement reporting message(s): (1) network layer packet delay, (2) network layer packet loss, (3) network layer jitter, (4) network layer throughput, etc. Additionally, and as discussed above, the example data collection facility  170  may combine measurement reporting messages received from multiple INIs to determine and report other (e.g., more complex) network performance measurements (e.g., such as network layer performance measurements associated with multi-hop network topologies). 
     After processing the received measurement reporting message(s) at block  1010 , control proceeds to block  1015  at which the example data collection facility  170  generates one or more performance report(s) based on the determined network performance measurements. The report(s) generated at block  1015  may be used, for example, to verify that the network whose performance is being measured is providing a level of service guaranteed by, for example, a service level agreement (SLA). Additionally or alternatively, the report(s) generated at block  1015  may be used to debug and/or improve network operation, and/or for any other purpose in which having network performance measurements may prove beneficial. After report generation at block  1015  completes, execution of the example machine readable instructions  1000  ends. 
       FIG. 11  is a block diagram of an example computer system  1100  capable of implementing the apparatus and methods disclosed herein. The computer  1100  can be, for example, a server, a personal computer, a personal digital assistant (PDA), an Internet appliance, a DVD player, a CD player, a digital video recorder, a personal video recorder, a set top box, or any other type of computing device. 
     The system  1100  of the instant example includes a processor  1112  such as a general purpose programmable processor. The processor  1112  includes a local memory  1114 , and executes coded instructions  1116  present in the local memory  1114  and/or in another memory device. The processor  1112  may execute, among other things, the machine readable instructions represented in  FIGS. 7 ,  8 A- 8 B,  9  and/or  10 . The processor  1112  may be any type of processing unit, such as one or more microprocessors from the Intel® Centrin® family of microprocessors, the Intel® Pentium® family of microprocessors, the Intel® Itanium® family of microprocessors, and/or the Intel XScale® family of processors. Of course, other processors from other families are also appropriate. 
     The processor  1112  is in communication with a main memory including a volatile memory  1118  and a non-volatile memory  1120  via a bus  1122 . The volatile memory  1118  may be implemented by Static Random Access Memory (SRAM), Synchronous Dynamic Random Access Memory (SDRAM), Dynamic Random Access Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM) and/or any other type of random access memory device. The non-volatile memory  1120  may be implemented by flash memory and/or any other desired type of memory device. Access to the main memory  1118 ,  1120  is typically controlled by a memory controller (not shown). 
     The system  1100  also includes an interface circuit  1124 . The interface circuit  1124  may be implemented by any type of interface standard, such as an Ethernet interface, a universal serial bus (USB), and/or a third generation input/output (3GIO) interface. 
     One or more input devices  1126  are connected to the interface circuit  1124 . The input device(s)  1126  permit a user to enter data and commands into the processor  1112 . The input device(s) can be implemented by, for example, a keyboard, a mouse, a touchscreen, a track-pad, a trackball, an isopoint and/or a voice recognition system. 
     One or more output devices  1128  are also connected to the interface circuit  1124 . The output devices  1128  can be implemented, for example, by display devices (e.g., a liquid crystal display, a cathode ray tube display (CRT)), by a printer and/or by speakers. The interface circuit  1124 , thus, typically includes a graphics driver card. 
     The interface circuit  1124  also includes a communication device such as a modem or network interface card to facilitate exchange of data with external computers via a network (e.g., an Ethernet connection, a digital subscriber line (DSL), a telephone line, coaxial cable, a cellular telephone system, etc.). For example, the interface circuit  1124  may implement the example network interface  510  of  FIGS. 5  and/or  6 . 
     The system  1100  also includes one or more mass storage devices  1130  for storing software and data. Examples of such mass storage devices  1130  include floppy disk drives, hard drive disks, compact disk drives and digital versatile disk (DVD) drives. 
     At least some of the above described example methods and/or apparatus are implemented by one or more software and/or firmware programs running on a computer processor. However, dedicated hardware implementations including, but not limited to, application specific integrated circuits, programmable logic arrays and other hardware devices can likewise be constructed to implement some or all of the example methods and/or apparatus described herein, either in whole or in part. Furthermore, alternative software implementations including, but not limited to, distributed processing or component/object distributed processing, parallel processing, or virtual machine processing can also be constructed to implement the example methods and/or apparatus described herein. 
     It should also be noted that the example software and/or firmware implementations described herein are optionally stored on a tangible storage medium, such as: a magnetic medium (e.g., a magnetic disk or tape); a magneto-optical or optical medium such as an optical disk; or a solid state medium such as a memory card or other package that houses one or more read-only (non-volatile) memories, random access memories, or other re-writable (volatile) memories; or a signal containing computer instructions. A digital file attached to e-mail or other information archive or set of archives is considered a distribution medium equivalent to a tangible storage medium. Accordingly, the example software and/or firmware described herein can be stored on a tangible storage medium or distribution medium such as those described above or successor storage media. 
     To the extent the above specification describes example components and functions with reference to particular standards and protocols, it is understood that the scope of this patent is not limited to such standards and protocols. For instance, each of the standards for Internet and other packet switched network transmission (e.g., Transmission Control Protocol (TCP)/Internet Protocol (IP), User Datagram Protocol (UDP)/IP, HyperText Markup Language (HTML), HyperText Transfer Protocol (HTTP)) represent examples of the current state of the art. Such standards are periodically superseded by faster or more efficient equivalents having the same general functionality. Accordingly, replacement standards and protocols having the same functions are equivalents which are contemplated by this patent and are intended to be included within the scope of the accompanying claims. 
     Additionally, although this patent discloses example systems including software or firmware executed on hardware, it should be noted that such systems are merely illustrative and should not be considered as limiting. For example, it is contemplated that any or all of these hardware and software components could be embodied exclusively in hardware, exclusively in software, exclusively in firmware or in some combination of hardware, firmware and/or software. Accordingly, while the above specification described example systems, methods and articles of manufacture, persons of ordinary skill in the art will readily appreciate that the examples are not the only way to implement such systems, methods and articles of manufacture. Therefore, although certain example methods, apparatus and articles of manufacture have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.