Metro ethernet connectivity fault management acceleration

Abstract

In an Ethernet network element comprising at least one line interface element and a central processing unit (CPU) to control forwarding of data packets at the network element, a method comprising receiving continuity check messages (CCMs) at the at least one line interface element, and processing the CCMs in the at least one line interface element to provide continuity checks for connections to the network element without requiring processing of CCMs by the CPU.

1 . In an Ethernet network element comprising at least one line interface element and a central processing unit (CPU), the CPU configured to control forwarding of data packets at the network element, a method comprising:
 receiving continuity check messages (CCMs) at the at least one line interface element; and   processing the CCMs in the at least one line interface element to provide continuity checks for connections to the network element without requiring processing of the CCMs by the CPU.   
     
     
         2 . The method of  claim 1 , wherein the network element is located at the edge of a connectivity fault management (CFM) domain. 
     
     
         3 . The method of  claim 1 , wherein processing CCMs comprises:
 determining that a received CCM contains invalid connection information; and   reporting the invalid connection information to the CPU.   
     
     
         4 . The method of  claim 1 , further comprising maintaining, by each line interface element, a respective list of connections that are supported by the line interface element. 
     
     
         5 . The method of  claim 4 , further comprising at a line interface element:
 receiving a CCM;   determining that connection information in the CCM does not align with connection information in the respective list of connections maintained by the line interface element; and   reporting the invalid connection information to the CPU.   
     
     
         6 . The method of  claim 4 , further comprising at each line interface element, associating a respective receive timer with each connection in the respective list of connections maintained by the line interface element. 
     
     
         7 . The method of  claim 6 , further comprising at the line interface element:
 receiving a CCM;   identifying a connection in the respective list of connections based on information in the CCM;   determining that the CCM contains correct connection information; and   resetting the respective receive timer associated with the identified connection in response to determining that the CCM contains correct connection information.   
     
     
         8 . The method of  claim 7 , wherein determining that the CCM contains correct connection information comprises determining that connection information in the CCM aligns with connection information in the respective list of connections maintained by the line interface element. 
     
     
         9 . The method of  claim 7 , wherein each respective receive timer expires if it reaches a predetermined value without being reset. 
     
     
         10 . The method of  claim 9 , further comprising at each line interface element associating a respective age counter with each connection in the respective list of connections maintained by the line interface element. 
     
     
         11 . The method of  claim 10 , further comprising at each line interface element, incrementing the respective age counter associated with a particular connection whenever the receive time for the particular connection expires. 
     
     
         12 . The method of  claim 11 , further comprising reporting to the CPU when a respective age counter exceeds a threshold. 
     
     
         13 . The method of  claim 4 , further comprising at a line interface element:
 associating a send timer with each connection in the respective list of connections maintained by the line interface element;   decrementing each send timer at regular time intervals; and   generating a CCM each time a send timer expires.   
     
     
         14 . The method of  claim 13 , further comprising each time a send timer expires, reloading the send timer with a respective value associated with the connection associated with the send timer. 
     
     
         15 . The method of  claim 13 , wherein decrementing each send timer at regular time intervals comprises decrementing the send timers in round robin fashion. 
     
     
         16 . The method of  claim 15 , comprising decrementing a send timer clock cycle. 
     
     
         17 . The method of  claim 13 , further comprising at the line interface element associating a respective strobe rate with each connection in the respective list of connections maintained by the line interface element, wherein decrementing each send timer at regular time intervals comprises decrementing each send timer at the respective strobe rate associated with the connection associated with the send timer. 
     
     
         18 . The method of  claim 13 , further comprising at the line interface element:
 associating a respective receive timer with each connection in the respective list of connections maintained by the line interface element; and   decrementing each respective receive timer when decrementing the send time associated with the same connection.   
     
     
         19 . The method of  claim 13 , wherein generating a CCM comprises:
 accessing connection information for the respective connection associated with the send timer in the list of connections maintained by the line interface element; and   putting the accessed connection information in the CCM.   
     
     
         20 . The method of  claim 1 , wherein each line interface element implements a respective CCM state machine. 
     
     
         21 . The method of  claim 20 , wherein each line interface element comprises:
 a respective Ethernet interface configured to interface with other nodes;   a respective frame analyzer coupled to the respective Ethernet interface, the frame analyzer implementing the respective CCM state machine;   at least one network processor coupled to the frame analyzer and configured to perform packet processing of incoming CCMs and to support generation of outgoing CCMs; and   a switch fabric interface coupled to the frame analyzer and configured to communicate with the CPU.