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  • 1.  Ethernet OAM CFM over EX Switch does not work when IGMP snooping is enabled.

    Posted 04-30-2013 01:08

    Just to document it somewhere because I sure didn't find it explained anywhere.

     

    Whe had the following setup:

     

    [MX80(rt1)] --- [EX4200] --- [MX80(rt2)]

     

    All three run JunOS 11.4R7.5.

     

    An OAM CFM Domain was configured on both of the MX80:

     

    rt1:

     

    root@rt1# show protocols oam     
    ethernet {
        connectivity-fault-management {
            action-profile port-down {
                event {
                    adjacency-loss;
                }
                action {
                    interface-down;
                }
            }
            maintenance-domain rt1-to-rt2 {
                level 3;
                maintenance-association rt1-to-rt2 {
                    continuity-check {
                        interval 1s;
                    }
                    mep 2 {
                        interface ge-1/0/0.3000;
                        direction down;
                        remote-mep 1 {
                            action-profile port-down;
                        }
                    }
                }                           
            }
        }
    }
    

     rt2:

     

    root@rt2# show protocols oam 
    ethernet {
        connectivity-fault-management {
            action-profile port-down {
                event {
                    adjacency-loss;
                }
                action {
                    interface-down;
                }
            }
            maintenance-domain rt1-to-rt2 {
                level 3;
                maintenance-association rt1-to-rt2 {
                    continuity-check {
                        interval 1s;
                    }
                    mep 1 {
                        interface ge-1/0/0.3000;
                        direction down;
                        remote-mep 2 {
                            action-profile port-down;
                        }
                    }
                }                           
            }
        }
    }
    

     

    The EX-Switch had a vlan with vlan-id 3000 configured which was used on both routers to communicate with each other.

     

    We had everything set up but couldn't get the CFM to establish between rt1 and rt2. I tried to debug it everywhere but didn't get anywhere until I disabled IGMP snooping on the EX for vlan-id 3000. Suddenly everything started to work, CFM came up and the port goes down whenevery the adjacency is lost to the other router, as it should be.

     

    I can't find any mention that IGMP snooping is impacting OAM CFM, so hopefully this gets picked up by Google and folks who have similar problems here.

     


    #EX
    #mx
    #switching
    #cfm
    #oam


  • 2.  RE: Ethernet OAM CFM over EX Switch does not work when IGMP snooping is enabled.
    Best Answer

    Posted 04-30-2013 01:42

    HI,

     

    Each MEP transmits a periodic multicast Continuity Check Message inward towards the other MEPs. That is why IGMP snooping must be disabled imho. 

     

    Thanks!

    Michael



  • 3.  RE: Ethernet OAM CFM over EX Switch does not work when IGMP snooping is enabled.

    Posted 04-30-2013 01:44

    You are right of course, but I really didn't realize that it is multicast until I found the solution. I think other folks might have the same problem. 🙂