Abstract:
A system and method for implementing telephony devices in a distributed network environment is disclosed. The present invention provides for checking data packets to ensure that non-voice data packets are properly tagged to be transmitted on a native virtual local area network (“VLAN”). Voice data packets transmitted on a separate VLAN with a higher priority.

Description:
RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application Ser. No. 60/285,507 filed Apr. 19, 2001, which is herein incorporated by reference for all purposes. 

   TECHNICAL FIELD OF THE INVENTION 
   The present invention relates generally to communication devices in a distributed network environment. In particular, the present invention relates to a system and method for implementing telephony devices in a distributed network environment, where data packets are checked to ensure that non-voice data packets are properly tagged to be transmitted on a native virtual local area network. 
   BACKGROUND OF THE INVENTION 
   Nearly all business telephone systems are based on a centralized or star network design. In such a conventional system, all telephones and trunk lines converge on a single switching point, typically, a public branch exchange (“PBX”) or in some cases a programmable switch. Despite the popularity of this conventional design, there are several problems with this kind of architecture. The problems include a single point of failure, proprietary closed architecture, and antiquated administration tools. 
   Conversely, telephony devices have more recently been implemented in distributed network environments, namely, Internet Protocol (IP) networks. In such systems IP telephony devices are used as end user devices (telephones) and to route data between nodes simultaneously, offering truly compelling benefits including no central point of failure, reduced tolls, essentially unlimited scalability, open architecture and user friendly administration tools. This is often called IP telephony. 
   Currently, IP telephony has limitations including poor quality of service. Poor quality of service for IP telephony includes, but is not limited to, packet delays or collisions which cause anomalies in the voice transmission on the receiver&#39;s end, and disconnection of the sender from the receiver due to discontinuity in the data stream. These problems can be attributed to the fact that the Internet is an unmanaged network of sub-networks with no resource allocation authority. As a result, it is common to encounter situations where there are too many users trying to communicate too much data through an already saturated pipeline. This problem is usually not present in corporate local or wide area networks since they generally have a resource allocation authority in the form of an engineer or manager. This person is usually responsible for designing a data network to have adequate bandwidth, redundant switching points, etc. However, if network traffic exceeds predicted levels in such a corporate local or wide area network, quality of service for IP telephony devices may also be poor. 
   SUMMARY OF THE INVENTION 
   The present invention relates generally to communication devices in a distributed network environment. In particular, the present invention relates to a system and method for implementing telephony devices in a distributed network environment, where voice transmissions are given a dedicated virtual local area network (“VLAN”), for packet transmission and reception, to prevent poor quality of service. In particular, the present invention provides a multiple port virtual local area network (“multi-VLAN port”) telephony device. The multi-VLAN port telephony device includes multiple physical ports. The data passing through these ports is selectively mapped to unique VLANs. In a first embodiment of the present invention, the multi-VLAN port telephony device uses the native VLAN for sending and receiving non-voice data traffic and uses an additional VLAN (“voice VLAN”) for sending and receiving voice data traffic. The VLAN assignments are made by a network switch residing on a network node, using a messaging system with a pre-defined protocol to communicate and assign VLANs to devices connected thereto. 
   A particular embodiment provides the technical advantage of discriminating data based upon data type such that the voice VLAN may be given a higher priority than the native VLAN, thus increasing the quality of service for voice communications. Further, having telephony devices on separate VLANs becomes extremely useful when a large number of telephony devices are added to an existing network where the number of available IP addresses is not high enough to accommodate the large number of telephony devices. A separate voice VLAN, in accordance with the present invention, provides a new subnet and a new set of IP addresses. 
   In accordance with another embodiment of the present invention, the network switch regulates and allocates power for a multi-VLAN port telephony device connected adjacent to the network switch, where the network switch is capable of providing power. This second embodiment provides the technical advantage of efficiently using available power at the network switch. In accordance with still another embodiment of the present invention, the multi-VLAN port telephony device re-marks the header of incoming packets to designate the appropriate VLAN. This third embodiment provides the technical advantage of ensuring that non-voice data traffic is properly marked and not sent on the voice VLAN. In this way, a sending device may not circumvent the VLAN assignments provided by the network switch of the present invention. 
   Other technical advantages of the present invention will be readily apparent to one skilled in the art from the following figures, descriptions, and claims. Moreover, while specific advantages have been enumerated above, various embodiments may include all, some, or none of the enumerated advantages. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings in which like reference numbers indicate like features, components and method steps, and wherein: 
       FIG. 1  is an illustration of a network switch, telephony device and external network device networked in accordance with a first exemplary embodiment of the present invention; 
       FIG. 2  is an illustration of telephony devices daisy chained in accordance with a second exemplary embodiment of the present invention; and 
       FIG. 3  is an illustration of a telephony device residing between and connected to two network switches in accordance with a third exemplary embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Now referring to the drawings,  FIG. 1  illustrates telephony system  100  that includes a network  101 , a network switch  102 , connected to a multiple virtual local area network (“VLAN”) port telephony device (“telephony device”)  104  and an external network device  106 . The external network device  106  may be a general purpose computer, computer server, or any other device which sends or receives data over a distributed network. A laptop is illustrated in  FIG. 1 , representative of any external network device  106 . 
   Network  101  represents any hardware and/or software configured to communicate information in the form of packets, cells, frames, segments, or other portions of data (generally referred to as “packets”). Network  101  may include routers, hubs, switches, gateways, or any other suitable components in any suitable form or arrangement. Network  101  may include a server  103 . Server  103  may assign network addresses to components of network  101 . For example, server  103  may be a dynamic host configuration protocol (DHCP) server  103  that assigns a network address to a component in response to a DHCP request. 
   Network switch  102  represents any hardware and/or software for switching packets between telephony device  104  and network  101 . Network switch  102  includes interface ports  120  and a memory  122 . Interface ports  120  represent any connection, real or virtual, allowing network switch  102  to exchange packets with other devices. Memory  122  represents any form of information storage, such as optical media, magnetic media, random access memory, read-only memory, programmable logic, removable media, or any other suitable component for storing information. Memory  122  stores a record  124  for each interface port  120 . Record  124  includes a port identifier  126 , a voice assignment  128 , and a data assignment  130 . The port identifier  126  identifies the corresponding port  120  that record  124  describes. Voice assignment  128  represents a tag identifying the VLAN to which voice data has been assigned. Non-voice assignment  130  represents a tag identifying the VLAN to which non-voice data has been assigned. A particular VLAN may include multiple ports, and a particular type of data may be assigned to multiple VLANs. The term “tag” refers to any suitable identifier that identifies a VLAN and that can be communicated as part of a packet, such a type-length-value (“TLV”) field. 
   The telephony device  104  includes multiple ports. The multiple ports include a network port (P 1 )  108 , an internal telephone port (P 2 )  110 , and an access port (P 3 )  114 . All three ports  108 ,  110  and  114  are interconnected by a port switch  116 . The port switch  116  defines the VLANs for the telephony device  104  and determines the types of data which propagate on which VLAN in response to messages received from the network switch  102 , as described below. The port switch  116  may contain a processor, firmware, random access memory, read only memory, flash memory EEPROM, and/or computer code to accomplish various tasks, described below, to control the data traffic at the telephony device  104 . The network port  108  interconnects the network switch  102  with the port switch  116 . The internal telephone port  110  interconnects an internal telephone circuit  112  with the port switch  116 . The access port  114  is also connected to the port switch  116 . The access port  114  provides a connection for the external network device  106  to connect to the telephony device  104  or, using the telephony device  104  as a conduit, to send data to the network switch  102 . 
   Alternatively, as depicted in  FIG. 2 , a second telephony device  202  may be connected to the telephony device  104 , in a daisy chain configuration via the access port  114  of the telephony device  104  and a network port  212  of the second telephony device  202 . In the exemplary embodiment of  FIG. 2 , the external network device  106  may then be connected to an access port  208  of the second telephony device  202 . In this configuration, data passing to and from the external network device  106  is passed through the second telephony device  202  and the first telephony device  104  to reach the network switch  102 , where the data will then be routed to its intended destination or received from a sender, respectively. 
   In accordance with one embodiment of system  100 , using  FIG. 2  as a reference solely for illustrative purposes, whenever the telephony device  104  is connected to an interface port  120  of the network switch  102  and powered up (“brought up” or “boot-up”), a discovery protocol (“DP”) message is sent through the interface port  120  to the telephony device  104 . This may be done, for example, three times at one second intervals to ensure reception. A DP message is a packetized message used to detect the existence or non-existence of voice and non-voice devices connected to the interface port  120  in accordance with a pre-defined protocol. Thereafter, the network switch  102  will send the DP message at a reduced frequency, for example once every 30–60 seconds. The DP message contains a voice VLAN identification (“VVID”) TLV). The VVID TLV value indicates to the telephony device  104  which VLAN it will transmit voice data on. The VVID value allows the telephony device  104  to get an IP address from a dynamic host configuration protocol (“DHCP”) server, such as server  103 , coupled directly or through any number of intermediate network components to network switch  102 . Thus, once the telephony device  104  has received a VVID TLV from the network switch  102 , it sends a DHCP request to the DHCP server to acquire an IP address, using the VVID TLV received from the network switch  102 . Further, from then on, all DP messages that the telephony device  104  sends out of the network port  108  and the access port  114  will always contain the VVID TLV as received and set by the network switch  102 . In response to these DP messages from the telephony device  104 , a neighboring telephony device, e.g., the second telephony device  202 , will receive the DP message and set its VVID TLV to the same value. In this way all devices on the network are in constant communication to ensure that new devices are properly configured when “brought-up.” 
   The telephony device  104  will take up to, for example, 3.5 seconds to boot-up and become operational. During this time, if the first three DP messages from the network switch  102  are sent, the telephony device  104  will not be ready to receive them. If this happens, the telephony device  104  will have to wait for up to 30–60 seconds to get the next DP message. In order to avoid this condition, the telephony device  104 , once becoming operational, sends a DP trigger TLV requesting the VVID TLV in the DP message that it sends out of the network port  108 . Therefore, if the telephony device  104  did not receive the DP message containing the VVID TLV, the DP trigger TLV message from the telephony device  104  will prompt the network switch  102  to re-send the DP message containing the VVID TLV using the same three DP messages in the one second interval scheme. Similarly, the second telephony device  202  also sends a DP trigger TLV to the first telephony device  104  when it becomes operational to prompt the first telephony device to send a DP message with the VVID TLV if not already received. In this way, each adjacent device provides the necessary VLAN information to its new adjacent device through DP messaging. 
   With respect to non-voice data packet transmission, a port VLAN identifier (“PVID”) on the interface port  120  is a native VLAN, which will be used to transmit and receive data to and from the external network device(s)  106  connected to the network switch  102 . The native VLAN may be the initial, first and base VLAN on a network and is usually assigned a VLAN number of zero. Therefore, system  100  assigns a first VLAN for exchanging non-voice packets with telephony device  104  and a second VLAN for exchanging voice packets with telephony device  104 . By specifying a first and a second VLAN depending on the type of traffic, network switch  102  may then direct the traffic to other network components coupled to network switch  102  in such a manner as to ensure higher quality of service for the second VLAN carrying voice packets. System  100  contemplates any configuration and arrangement of other network components coupled to network switch  102 , such as hubs, routers, switches, and other devices, to deliver the network performance of the second VLAN for quality voice communications. Voice data packets and non-voice packets are not commingled, thereby ensuring a quality of service for voice data packet transmission. If the telephony devices  104 ,  202  are connected in a daisy chain, as in  FIG. 2 , the PVID will correspond only to the external network device  106  on the access port  208  of the last telephony device  202  in the daisy chain. 
     FIG. 3  illustrates another exemplary embodiment of system  100 , where the telephony device  104  is connected to both the first network switch  102  and a second network switch  302 . Under this embodiment, once the telephony device  104  is “brought up,” it sends a DP trigger TLV message on both the network port  108  and the access port  114 . If the telephony device  104  receives the DP message from both the first network switch  102  and the second network switch  302 , it uses the first VVID TLV of the first DP message received and then reports out in its own network port  108  and access port  114  a DP message containing the VVID TLV it currently has. This essentially functions as a first-come, first-serve basis VVID TLV assignment scheme. 
   In accordance with another embodiment of system  100 , the network switch  102  can supply in-line power through one or more interface ports  120 . The network switch  102  includes the capability to supply power to the telephony device  104  directly connected to the network switch  102 , and any other device directly connected to network switch  102 , thereby directly servicing multiple devices. System  100  has a default wattage for the power consumed by any telephony device, which will be the maximum power consumed by any telephony device  104  known to the network switch  102 . When the telephony device  104  is detected by the network switch  102 , it does power budget calculations using the default power value to find out if it can supply power to the newly inserted telephony device  104 . If sufficient power exists at the network device  102 , the network device  102  will provide power at the interface port  120  for the telephony device  104  directly connected thereto. 
   The telephony device  104  that is plugged into the interface port  120  will then begin receiving power from the interface port  120 , but not necessarily the default power. The telephony device  104  may be drawing less power if it is a known less power-consuming device or it may be drawing more if it is an unknown new device which requires more power. In either case, in accordance with an exemplary embodiment, the telephony device  104  identifies the actual power that it needs in milliwatts using a 16-bit value by sending a DP message through the network port  108  to the network switch  102 . Upon receiving the actual power needed, the network switch  102  corrects the value in the power budget accordingly. The power consumed by a telephony device  104  is approximately five watts in an exemplary embodiment. 
   In accordance with another embodiment, the telephony device  104  may be enabled to verify the type of data received in a packet through the access port  114  and whether the data has been properly tagged with the correct VLAN. Many times devices attempting to gain better bandwidth will disguise non-voice data packets as voice data packets in order to be placed on the better performing voice VLAN reserved solely for voice data packets. In order to prevent this behavior, the access port  114  of the telephony device  104  may be toggled between a “trusted” and “untrusted” mode by the network switch  102 . This state is toggled by the network switch  102  sending such a command in a DP message. Once placed in an “untrusted” mode, the telephony device  104  checks the contents of all incoming packets through the access port  114  to determine whether such packets are voice or non-voice packets and whether the correct VLAN identifier is in the packet header. If the correct VLAN is identified, the packet header is not modified. Alternatively, all packets may be re-tagged with the appropriate voice VLAN or native VLAN tags, thus eliminating the step of determining what VLAN tag appears in the header of the packet upon reception. If “trusted” mode, the default mode, is triggered by the network switch  102 , all the packets received on the access port  114  will pass through as they are tagged when received, without the VLAN value being re-marked or otherwise checked. Similarly with respect to the VVID TLV information discussed above, in a daisy chain configuration of multiple telephony devices  104 ,  202 , as in  FIG. 2 , after receiving a DP message containing a “trusted” or “untrusted” mode from the network switch  102 , the telephony device  104  then sends a DP message to the second telephony device  202  to perform the same “trusted” or “untrusted” operation. 
   Although the present invention has been described in detail with reference to specific exemplary embodiments thereof, various modifications, alterations and adaptations may be made by those skilled in the art without departing from the spirit and scope of the invention. It is intended that the invention be limited only by the appended claims.