Ethernet Switching
Ethernet Switching

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

[ Edited ]
‎04-30-2013 01:07 AM

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.

 

--
Sebastian Wiesinger
JNCIS-SP
2 REPLIES 2
Ethernet Switching
Solution
Accepted by topic author sebastianw
‎08-26-2015 01:27 AM

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

‎04-30-2013 01:41 AM

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

Highlighted
Ethernet Switching

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

[ Edited ]
‎04-30-2013 01:43 AM

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. Smiley Happy

--
Sebastian Wiesinger
JNCIS-SP