Hierarchical virtual private lan service protection scheme

Abstract

A data communication network includes a plurality of primary virtual bridges, interconnected by primary virtual connections so as to transmit and receive data packets over the network to and from edge devices connected thereto. One or more backup virtual bridges, each associated with at least one of the primary virtual bridges, are connected by at least one secondary virtual connection to at least another one of the primary virtual bridges, so that upon a failure of one of the primary virtual bridges with which it is associated, the backup virtual bridge transmits and receives the data packets over the network via the at least one secondary virtual connection in place of the at least one of the primary virtual bridges.

1 . A date communication network, comprising; 
 a plurality of primary virtual bridges, interconnected by primary virtual connections so as to transmit and receive data packets over the network to and from edge devices connected thereto, wherein the primary virtual connections define a respective primary topology image for each of the primary virtual bridges; and    a corresponding plurality of backup virtual bridges, wherein each of the backup virtual bridges is paired with a corresponding one of the primary virtual bridges and is connected to the other primary virtual bridges by secondary virtual connections that are identical to the primary virtual connections of the corresponding one of the primary virtual bridges, thus defining a respective secondary topology image that is identical to the respective primary topology image of the corresponding one of the primary virtual bridges,    wherein upon a failure of the corresponding one of the primary virtual bridges with which it is associated, each of the backup virtual bridges forwards and receives the data packets over the network via the secondary virtual connections in place of the corresponding one of the primary virtual bridges.    
   
   
       2 . The network according to  claim 1 , wherein each of the primary and backup virtual bridges is adapted to maintain a respective media access control (MAC) table, and to forward the data packets in accordance with entries in the MAC table.  
   
   
       3 . The network according to  claim 2 , wherein each of the primary virtual bridges is adapted, upon detecting the failure of one of the primary virtual bridges, to update the entries in the respective MAC table that point to the one of the primary virtual bridges so as to point instead to the corresponding one of the backup virtual bridges.  
   
   
       4 . The network according to  claim 2 , wherein each of the backup virtual bridges is adapted, following the failure of the corresponding one of the primary virtual bridges, to update the entries in the respective MAC table using a MAC learning process.  
   
   
       5 . The network according to  claim 4 , wherein each of the backup virtual bridges is adapted, while the corresponding one of the primary virtual bridges with which it is paired is operational, to periodically synchronize its MAC table with the MAC table of the corresponding one of the primary virtual bridges.  
   
   
       6 . The network according to  claim 1 , wherein the primary and backup virtual bridges are adapted to transmit the packets over the network by tunneling through the network.  
   
   
       7 . The network according to  claim 6 , wherein the primary and backup virtual bridges are arranged to transmit the packets using a virtual private LAN service (VPLS).  
   
   
       8 . The network according to  claim 7 , wherein the primary and backup virtual bridges are adapted to serve as provider edge (PE) devices, and to transmit the packets over pseudo-wires (PWs) connecting to the edge devices.  
   
   
       9 . The network according to  claim 1 , wherein the primary virtual connections define a first full mesh of the primary virtual bridges, and wherein each of the backup virtual bridges is connected by the secondary virtual connections to both the primary virtual bridges and to the other backup virtual bridges so as to define a second full mesh of the backup virtual bridges and a third full mesh between each one of the backup virtual bridges and the primary virtual bridges, except for the corresponding one of the primary virtual bridges with which the backup virtual bridge is paired.  
   
   
       10 . The network according to  claim 1 , wherein each of the backup virtual bridges is connected by secondary virtual connections to both the primary virtual bridges and to the other backup virtual bridges, so that the primary and secondary virtual connections define a full mesh of all the primary and backup virtual bridges.  
   
   
       11 . The network according to  claim 1 , wherein each of the edge devices is connected both to a respective one of the backup virtual bridges and to the corresponding one of the primary virtual bridges with which the respective one of the backup virtual bridges is paired, so that upon detecting the failure of the corresponding one of the primary virtual bridges, the edge devices communicate with the network through the respective one of the backup virtual bridges instead of the corresponding one of the primary virtual bridges.  
   
   
       12 . The network according to  claim 11 , wherein the primary virtual bridges are adapted, upon receiving packets sent by the edge devices through the backup virtual bridge, to communicate with the respective one of the backup virtual bridges instead of the one of the primary virtual bridges in which the failure occurred.  
   
   
       13 . A method for data communication, comprising: 
 interconnecting a plurality of primary virtual bridges using primary virtual connections through a network, wherein the primary virtual connections define a respective primary topology image for each of the primary virtual bridges; 
 linking the primary virtual bridges to edge devices, so as to enable the edge devices to transmit and receive data packets over the network via the primary virtual connections;  
 associating a plurality of backup virtual bridges with the plurality of the primary virtual bridges, such that each of the backup virtual bridges is paired with a corresponding one of the primary virtual bridges;  
 configuring secondary virtual connections between the backup virtual bridges and the primary virtual bridges such that each of the backup virtual bridges is connected to the other primary virtual bridges by secondary virtual connections that are identical to the primary virtual connections of the corresponding one of the primary virtual bridges, thus defining a respective secondary topology image that is identical to the respective primary topology image of the corresponding one of the primary virtual bridges; and  
 upon a failure of the corresponding one of the primary virtual bridges, forwarding and receiving the data packets to and from the edge devices via the secondary virtual connections using one of the backup virtual bridges in place of the corresponding one of the primary virtual bridges.  
   
   
   
       14 . The method according to  claim 13 , and comprising maintaining a respective media access control (MAC) table at each of the primary and backup virtual bridges, wherein forwarding the data packets comprises forwarding the data packets in accordance with entries in the respective MAC table.  
   
   
       15 . The method according to  claim 14 , wherein forwarding the data packets comprises, upon detecting the failure of one of the primary virtual bridges, updating the entries that point to the one of the primary virtual bridges in the respective MAC table of others of the primary virtual bridges so as to point instead to the corresponding one of the backup virtual bridges.  
   
   
       16 . The method according to  claim 14 , wherein forwarding the data packets comprises, following the failure of the corresponding one of the primary virtual bridges, updating the entries in the respective MAC table of the one of the backup virtual bridges using a MAC learning process.  
   
   
       17 . The method according to  claim 16 , and comprising, while the corresponding one of the primary virtual bridges with which it is paired is operational, periodically synchronizing the MAC table of each of the backup virtual bridges with the MAC table of the corresponding one of the primary virtual bridges.  
   
   
       18 . The method according to  claim 13 , wherein forwarding and receiving the packets comprises transmitting the packets by tunneling through the network.  
   
   
       19 . The method according to  claim 18 , wherein transmitting the packets comprises forwarding and receiving the packets using a virtual private LAN service (VPLS).  
   
   
       20 . The method according to  claim 19 , wherein the primary and backup virtual bridges are adapted to serve as provider edge (PE) devices, and wherein forwarding and receiving the packets comprises forwarding and receiving the packets over pseudo-wires (PWs) connecting to the PE devices.  
   
   
       21 . The method according to  claim 13 , wherein interconnecting the plurality of primary virtual bridges comprises arranging the primary virtual connections to define a first full mesh of the primary virtual bridges, and wherein configuring the secondary virtual connections comprises arranging the secondary virtual connections to define a second full mesh of the backup virtual bridges and a third full mesh between each one of the backup virtual bridges and the primary virtual bridges, except for the corresponding one of the primary virtual bridges with which the backup virtual bridges is paired.  
   
   
       22 . The method according to  claim 13 , wherein interconnecting the plurality of primary virtual bridges and configuring the secondary virtual connections comprise configuring the primary and secondary virtual connections so as to define a full mesh of all the primary and secondary virtual bridges.  
   
   
       23 . The method according to  claim 13 , wherein configuring the secondary virtual connections comprises connecting each of the edge devices to a respective one of the backup virtual bridges, in addition to the corresponding one of the primary virtual bridges with which the respective one of the backup virtual bridges is paired, and wherein forwarding and receiving the data packets comprises detecting the failure of the corresponding one of the primary virtual bridges at one or more of the edge devices, and initiating communication from the one or more of the edge devices to the one of the backup virtual bridges in response to detecting the failure.  
   
   
       24 . The method according to  claim 23 , wherein forwarding and receiving the data packets further comprises receiving at the primary virtual bridges the data packets sent by the edge devices through the one of the backup virtual bridges, and in response to receiving the data packets, diverting communication traffic from the primary virtual bridges to the one of the backup virtual bridges.