Abstract:
Aspects of the present invention include multi-homed node in a port extender environment. In embodiments of the present invention, each port extender can communicate data traffic to the multi-homed node thereby increasing the number of available links to the multi-homed node. The communication with the multi-homed node is based on an identification associated with the data traffic.

Description:
BACKGROUND 
       [0001]    1. Field of Invention 
         [0002]    The present invention relates generally to data communication networks and devices, and relates more particularly to port extender environments. 
         [0003]    2. Description of the Related Art 
         [0004]    As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems. 
         [0005]    As information handling systems provide increasingly more central and critical operations in modern society, it is important that the networks are reliable. One method used to improve reliability is to provide redundant links between network devices. By employing redundant links, network traffic between two network devices that would normally be interrupted can be re-routed to the back-up link in the event that the primary link fails. 
         [0006]    In a network switch, there are a limited number of ports and each switch is managed individually. This complicates the management of switches within the network. One way to decrease the complexity in management of switches and increase the number of ports is to use port extenders. Port extension provides the capability to group different switches into a single logical switch, thus making it easier to manage different switches and also increases the number of ports which can be managed. In a port extender environment, a single controlling point is needed to manage the different switches and these managed switches are called the port extenders. In a port extender environment, there can be multi-homed nodes, meaning a node that is connected to more than one port extender. 
         [0007]    In some prior art solutions, a controlling bridge is used as the controlling point in a multi-homed network. In prior art solutions, the port extenders blindly forward a packet of data to the controlling bridge via the uplink port. 
         [0008]      FIG. 1  shows an example of a prior art solution.  FIG. 1  shows controlling bridge  105 , three port extenders  110 ,  115 , and  120 , three receivers  125 ,  130 , and  135 , and multi-homed node  140 . In this example, there are three port extenders, PE 1   120 , PE 2   115 , and PE 3   110 . Each port extender can be a different switch. Each port in a port extender is known as an Extended Port and has a E-channel identifier (ECID). This would be used at the controlling bridge to identify the extended port present in the port extender in which the packet has come in. This E-channel identifier (ECID) is also used during transmission of a packet from the controlling bridge to an extended port present in the port extender. The E-channel identifier is encoded within a tag called the ETAG. 
         [0009]    To identify on which port the packet comes in, the port extender adds a tag called ETAG in the packet and fills the channel identifier field in the ETAG. When a packet comes in on the downlink port, the port extender  110 ,  115 , or  120  fills the channel identifier associated with the downlink port in the ETAG and forwards it to the controlling bridge  105 . The controlling bridge  105  reads the E-Channel Identifier (ECID) from the ETAG and sees from which port the packet came. 
         [0010]    There are virtual ports for each extended port present in the port extender  110 ,  115 , and  120  at the controlling bridge  105 . At the controlling bridge  105  there is a routing table look-up. If the destination is another port extender, the controlling bridge will have a table to look at the position and figure out the destination. The controlling bridge  105  will add an ETAG, fill the E-Channel Identifier (ECID) of the extended port and will forward the packet to the port extender  110 ,  115 , and  120 . 
         [0011]    For example, if a unicast packet is traveling from port  148  in PE 1   120  to port  152  in PE 3   110 , then PE 1   120  will send the packet to the controlling bridge  105  on uplink  142  by filling the E-Channel identifier of the extender port  148 . After the lookup in Media Access Control (MAC) Address table for the unicast packet the controlling bridge  105  will add or modify the ETAG by filling the E-Channel Identifier (ECID) of the final destination port  152  and send the packet to PE 3   110  on downlink  144 . At PE 3   110 , PE 3   110  will look at the E-Channel Identifier (ECID) present in the ETAG and it will send it out to the receiver  135  on downlink  152 . 
         [0012]    In the above example, for a non-unicast case, a packet comes from PE 1   120 , PE 1   120  will add an ETAG and an ingress E-Channel Identifier (ECID). PE 1   120  will also send the packet to the controlling bridge  105 . At the controlling bridge  105 , there is no entry in the Media Access Control (MAC) Address table because it is not a unicast packet. Therefore, the controlling bridge will flood the packet out on the Virtual Local Area Networks (VLANs) to PE 2   115  and PE 3   110 . Each VLAN will have a multi-cast ECID. A flooded packet will form a tree  142 ,  144 ,  146 ,  148 ,  150 ,  152 , and  156 . 
         [0013]    In the example all the port extenders  110 ,  115 , and  120  are connected to the same multi-homed node  140 , so only one port extender sends the packet to the multi-homed node  140 . In the example, PE 1   120  sends the packet to the multi-homed node  140 . If more than one port extender sent the packet, the multi-homed node would receive duplicate packets. 
         [0014]    The problem is that only one port extender, PE 1   120 , sends packets to the multi-homed node  140 . PE 2   115  and PE 3   110  never would send the packet to the multi-homed node  140 . 
         [0015]    One disadvantage of this system is that only one link is active per VLAN or per multicast group. 
         [0016]    Accordingly, what is needed are systems and methods that can have more than one active link per VLAN. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures, in which like parts may be referred to by like or similar numerals. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the spirit and scope of the invention to these particular embodiments. These drawings shall in no way limit any changes in form and detail that may be made to the invention by one skilled in the art without departing from the spirit and scope of the invention. 
           [0018]      FIG. 1  depicts an example of a multi-homed node. 
           [0019]      FIG. 2  depicts an example of a multi-homed node according to embodiments of the present invention. 
           [0020]      FIG. 3  depicts an example of using a hash flow algorithm according to embodiments of the present invention. 
           [0021]      FIG. 4  depicts a block diagram according to embodiments of the present invention. 
           [0022]      FIG. 5  depicts a flowchart for data distribution according to embodiments of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    In the following description, for purposes of explanation, specific examples and details are set forth in order to provide an understanding of the invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without these details. Well known process steps may not be described in detail in order to avoid unnecessarily obscuring the present invention. Other applications are possible, such that the following examples should not be taken as limiting. Furthermore, one skilled in the art will recognize that aspects of the present invention, described herein, may be implemented in a variety of ways, including software, hardware, firmware, or combinations thereof. 
         [0024]    Components, or modules, shown in block diagrams are illustrative of exemplary embodiments of the invention and are meant to avoid obscuring the invention. It shall also be understood that throughout this discussion that components may be described as separate functional units, which may comprise sub-units, but those skilled in the art will recognize that various components, or portions thereof, may be divided into separate components or may be integrated together, including integrated within a single system or component. It should be noted that functions or operations discussed herein may be implemented as components or modules. 
         [0025]    Furthermore, connections between components within the figures are not intended to be limited to direct connections. Rather, data between these components may be modified, re-formatted, or otherwise changed by intermediary components (which may or may not be shown in the figure). Also, additional or fewer connections may be used. It shall also be noted that the terms “coupled” or “communicatively coupled” shall be understood to include direct connections, indirect connections through one or more intermediary devices, and wireless connections. 
         [0026]    In the detailed description provided herein, references are made to the accompanying figures, which form a part of the description and in which are shown, by way of illustration, specific embodiments of the present invention. Although these embodiments are described in sufficient detail to enable one skilled in the art to practice the invention, it shall be understood that these examples are not limiting, such that other embodiments may be used, and changes may be made without departing from the spirit and scope of the invention. 
         [0027]    Reference in the specification to “one embodiment,” “preferred embodiment,” “an embodiment,” or “embodiments” means that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention and may be in more than one embodiment. Also, such phrases in various places in the specification are not necessarily all referring to the same embodiment or embodiments. It shall be noted that the use of the terms “set” and “group” in this patent document shall include any number of elements. Furthermore, it shall be noted that methods or algorithms steps may not be limited to the specific order set forth herein; rather, one skilled in the art shall recognize, in some embodiments, that more or fewer steps may be performed, that certain steps may optionally be performed, and that steps may be performed in different orders, including being done some steps being done concurrently. 
         [0028]    The present invention relates in various embodiments to devices, systems, methods, and instructions stored on one or more non-transitory computer-readable media involving the communication of data over networks. Such devices, systems, methods, and instructions stored on one or more non-transitory computer-readable media can result in, among other advantages, better bandwidth usage, better scalability, and better reliability by mitigating the effects of down links and other points of failure across data networks. The terms “packet” or “frame” shall be understood to mean a group of bits that can be transported across a network. The term “frame” shall not be interpreted as limiting embodiments of the present invention to Layer 2 networks; and, the term “packet” shall not be interpreted as limiting embodiments of the present invention to Layer 3 networks. The terms “packet,” “frame,” “data,” or “data traffic” may be replaced by other terminologies referring to a group of bits, such as “datagram” or “cell.” One skilled in the art shall recognize that references herein to Media Access Control (MAC) address may, depending upon context, refer to MAC-VLAN combination. 
         [0029]    It shall also be noted that although embodiments described herein may be within the context of non-unicast transmission and multi-homed nodes, the invention elements of the current patent document are not so limited. Accordingly, the invention elements may be applied or adapted for use in other contexts. 
         [0030]    As described above, in prior art solutions, when a node is multi-homed to different port extenders, non-unicast data traffic from a controlling bridge is allowed to flow from only one of the designated port extenders to avoid reception of duplicate packets. Typically the designated port extender is chosen on a per VLAN or on a per group basis. Although this system provides distribution of non-unicast data over the multi-homed links, only one link is active for a VLAN or for a multicast group. In embodiments of the present invention the restriction of having only one link active per VLAN or per multicast group when a node is multi-homed to different port extenders is removed. Thus advantages can be achieved, such as redundancy, better bandwidth utilization, and faster recovery in the event one of the multi-homed links goes down. 
         [0031]      FIG. 2  depicts an example of a multi-homed node according to embodiments of the present invention.  FIG. 2  shows a multi-homed node with three trees. The example in  FIG. 2  illustrates the case of three port extenders connected to the same multi-homed node. However, one of ordinary skill in the art will appreciate that three port extenders is chosen for ease of explanation and is not intended to limit the number of port extenders to any particular number. 
         [0032]      FIG. 2  shows controlling bridge  205 , port extenders  210 ,  215 , and  220 , receivers  225 ,  230 , and  235 , and multi-homed node  240 .  FIG. 2  also shows three trees as shown in box  285 . The first tree is shown by communications links  242 ,  244 ,  246 ,  248 ,  250 ,  252 , and  254 . The second tree is shown by communications links  256 ,  258 ,  260 ,  262 ,  264 ,  266 , and  268 . The third tree is shown by communications links  270 ,  272 ,  274 ,  276 ,  278 ,  280 , and  282 . 
         [0033]    An example of communication flow in accordance with the embodiment shown in  FIG. 2  is that when a packet comes in to the controlling bridge  205  from a particular port extender  210 ,  215 , or  220 , it would be flooded to other port extenders  210 ,  215 , and  220  and therefore to receivers  225 ,  230 , and  235 . Also, one port extender  210 ,  215 , or  220  can forward the packet to the multi-homed node  240 . However, only one port extender  210 ,  215 , or  220  will forward the packet to the multi-homed node  240 . The determination of which port extender  210 ,  215 , or  220  is based on the E-Channel Identifier (ECID). 
         [0034]    The controlling bridge selects a multicast ECID. The port extender to forward to the multi-homed node  240  is based on the ECID used. Since all the port extenders can forward to the multi-homed node, more than one link is used to connect to the multi-homed node  240 . 
         [0035]    In some embodiments of the present invention, when a multi-homed node  240  is in the multicast replication path, the controlling bridge  205  can create a multicast replication tree bundle  285 . The multicast replication tree bundle could contain multicast replication trees where each tree would have one of the links in to the port extender  210 ,  215 , or  220  connecting to a multi-homed node  240  as a branch. 
         [0036]    In embodiments of the present invention, each of trees within the tree bundle could be identified by a multicast ECID. The port extenders connected to the multi-homed node could be configured in such a way that only one of them could forward to the multi-homed node for each multicast ECID within the tree bundle. 
         [0037]    In embodiments of the present invention, hardware flow based hashing mechanism could be used to choose one of the trees within the tree bundle. So for different non-unicast flows on the same VLAN, different trees could be chosen and hence traffic would flow on different multi-homed links, achieving better distribution. 
         [0038]      FIG. 3  depicts an example of using a hash flow algorithm according to embodiments of the present invention.  FIG. 3  shows stream  1   305 , stream  2   310 , and stream  3   315  as inputs to hash flow algorithm  320 .  FIG. 3  also shows tree  1 , ECID X, egress points  325 , tree  2  ECID Y, egress points  330 , and tree  3  ECID Z, egress points  335 .  FIG. 3  shows using a flow hash modulo n  320 , where n is the number of trees in the tree bundle. 
         [0039]      FIG. 4  depicts a block diagram according to embodiments of the present invention.  FIG. 4  shows port extender environment  400  including three port extenders  405 ,  410 , and  415 , controlling bridge  420 , hashing flow module  425 , and multi-homed node  440 . Multi-homed node  240  includes ingress port  435  and egress port  430 . 
         [0040]      FIG. 5  depicts a flowchart for data distribution according to embodiments of the present invention.  FIG. 5  shows flow  500  including use multi-cast in a multi-homed port extender environment  505 , use a controlling bridge to connect a plurality of port extenders  510 , use a hash based modulo n algorithm to create ECID that a forms tree bundle  515 , and select port extender based on ECID  520 . Using this method allows for multiple links to the multi-homed node. 
         [0041]    Embodiments of the present invention have many advantages. For example, they allow better bandwidth utilization of the multi homed links. Other advantages include faster recovery in case when one of the multi-homed links goes down. For example, if one the multi-homed links connecting to the port extender goes down, the controlling bridge would just need to remove the tree which has this link from the tree bundle. Once that tree is removed from the tree bundle, traffic could start flowing immediately through alternate multi-homed link as the hash compute is modulo N. The controlling bridge need not reprogram the paths at the port extenders if the multi-homed links go down. 
         [0042]    It shall be noted that aspects of the present invention may be encoded upon one or more non-transitory computer-readable media with instructions for one or more processors or processing units to cause steps to be performed. It shall be noted that the one or more non-transitory computer-readable media shall include volatile and non-volatile memory. It shall be noted that alternative implementations are possible, including a hardware implementation or a software/hardware implementation. Hardware-implemented functions may be realized using ASIC(s), programmable arrays, digital signal processing circuitry, or the like. Accordingly, the “means” terms in any claims are intended to cover both software and hardware implementations. Similarly, the term “computer-readable medium or media” as used herein includes software and/or hardware having a program of instructions embodied thereon, or a combination thereof. With these implementation alternatives in mind, it is to be understood that the figures and accompanying description provide the functional information one skilled in the art would require to write program code (i.e., software) and/or to fabricate circuits (i.e., hardware) to perform the processing required. 
         [0043]    While the inventions have been described in conjunction with several specific embodiments, it is evident to those skilled in the art that many further alternatives, modifications, application, and variations will be apparent in light of the foregoing description. Thus, the inventions described herein are intended to embrace all such alternatives, modifications, applications and variations as may fall within the spirit and scope of the appended claims.