How to Configure Ethernet CFM across Multiple Domains Using Junos

By Walter J. Goralski, Cathy Gadecki, Michael Bushong

A rather complicated network can have three CFM levels: core (Level 3), provider (Level 5), and customer (Level 7). This number of CFM levels is not uncommon in large enterprise configurations.

Configuring Ethernet CFM across multiple domains.

Configuring Ethernet CFM across multiple domains.

The configuration shows only the relevant Ethernet OAM parameters. Although it seems long, the configuration establishes only a few parameters for the customerCE maintenance domain and associated MEPs. Both sites match parameters for the interval at which continuity checks are carried out (1 second) and the MEP direction (down from Level 7 to Level 5), and both establish auto-discovery for paths between MAC addresses.

Configuration on CE1

user@CE1-router>protocols oam management connectivity-fault-management
       maintenance-domain customerCE level 7
user@CE1-router>protocols oam management connectivity-fault-management
       maintenance-domain customerCE maintenance-association 
       customer-site-CE1 continuity-check interval 1s
user@CE1-router>protocols oam management connectivity-fault-management
        maintenance-domain customerCE maintenance-association 
        customer-site-CE1 mep 700 interface ge-0/2/9.0 direction down
user@CE1-router>protocols oam management connectivity-fault-management
        maintenance-domain customerCE maintenance-association customer-site-CE1
        mep 700 interface ge-0/2/9.0 auto-discovery
user@CE1-router>show protocols oam management connectivity-fault-management
maintenance-domain customerCE {
    level 7;
    maintenance-association customer-site-CE1 {
        continuity-check {
interval 1s;
        }
        mep 700 {
            interface ge-0/2/9.0; 
            direction down;
            auto-discovery;
        }
    }
}

Configuration on CE2

user@CE2-router>protocols oam management connectivity-fault-management
       maintenance-domain customerCE level 7
user@CE2-router>protocols oam management connectivity-fault-management
       maintenance-domain customerCE maintenance-association customer-site-CE2
       continuity-check interval 1s
user@CE2-router>protocols oam management connectivity-fault-management
       maintenance-domain customerCE maintenance-association customer-site-CE2
       mep 800 interface ge-1/0/7.0 direction down
user@CE2-router>protocols oam management connectivity-fault-management
       maintenance-domain customerCE maintenance-association customer-site-CE2
       mep 700 interface ge-1/2/7.0 auto-discovery
user@CE2-router>show protocols oam management connectivity-fault-management
maintenance-domain customerCE {
    level 7;
    maintenance-association customer-site-CE2 {
        continuity-check {
interval 1s;
        }
        mep 800 {
            interface ge-1/0/7.0; 
            direction down;
            auto-discovery;
        }
    }
}

CFM on the two provider routers, PE1-router and PE2-router, is a bit more complicated because you must configure two sets of interfaces and MEPs (provider-outer and provider-inner). Aside from the maintenance domain and MEP names and directions, the interfaces all use a 1 second continuity check interval and auto-discovery of paths.

Configuration on PE1

user@PE1-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-outer level 5
user@PE1-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-outer maintenance-association 
       provider-outer-site-PE1 continuity-check interval 1s
user@PE1-router>protocols oam management connectivity-fault-management 
       maintenance-domain provider-outer maintenance-association 
       provider-outer-site-PE1 mep 100 interface ge-5/0/9.0 direction up
user@PE1-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-outer maintenance-association 
       provider-outer-site-PE mep 100 interface ge-5/0/9.0 auto-discovery
user@PE1-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-inner level 3
user@PE1-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-inner maintenance-association 
       provider-inner-site-PE continuity-check interval 1s
user@PE1-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-inner maintenance-association 
       provider-inner-site-PE mep 100 interface ge-5/1/7.0 direction down
user@PE1-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-inner maintenance-association 
       provider-inner-site-PE mep 100 interface ge-5/1/7.0 auto-discovery
user@PE1-router>show protocols oam management connectivity-fault-management
maintenance-domain provider-outer {
    level 5;
    maintenance-association provider-outer-site-PE {
        continuity-check {
            interval 1s;
        }
        mep 100 {
            interface ge-5/0/9;
            direction up;
            auto-discovery;
            }
        }
    }
maintenance-domain provider-outer {
    level 3;
    maintenance-association provider-outer-site-PE {
        continuity-check {
            interval 1s;
        }
        mep 100 {
            interface ge-5/1/7;
            direction down;
            auto-discovery;
            }
        }
    }
}

Configuration on PE2

user@PE2-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-outer level 5
user@PE2-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-outer maintenance-association 
      provider-outer-site-PE continuity-check interval 1s
user@PE2-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-outer maintenance-association 
      provider-outer-site-PE mep 200 interface ge-5/2/3.0 direction up
user@PE2-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-outer maintenance-association 
      provider-outer-site-PE mep 200 interface ge-5/2/3.0 auto-discovery
user@PE2-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-inner level 3
user@PE2-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-inner maintenance-association 
       provider-inner-site-PE continuity-check interval 1s
user@PE2-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-inner maintenance-association 
      provider-inner-site-PE mep 200 interface ge-5/1/7.0 direction down
user@PE2-router>protocols oam management connectivity-fault-management
       maintenance-domain provider-inner maintenance-association 
      provider-inner-site-PE mep 200 interface ge-5/1/7.0 auto-discovery
user@PE2-router>show protocols oam management connectivity-fault-management
maintenance-domain provider-outer {
    level 5;
    maintenance-association provider-outer-site-PE {
        continuity-check {
            interval 1s;
        }
        mep 200 {
            interface ge-5/2/3;
            direction up;
            auto-discovery;
            }
        }
    }
maintenance-domain provider-outer {
    level 3;
    maintenance-association provider-outer-site-PE {
        continuity-check {
            interval 1s;
        }
        mep 200 {
            interface ge-5/1/7;
            direction down;
            auto-discovery;
            }
        }
    }
}

Now you can examine the continuity check message (CCM) status (and other events) on the interface:

user@host> show oam ethernet connectivity-fault-management interfaces 
      ge-0/2/9 detail
Interface name: ge-0/2/9.0, Interface status: Active, Link status: Up
   Maintenance domain name: customer, Format: string, Level: 7
    Maintenance association name: customer-site1, Format: string
     Continuity-check status: enabled, Interval: 1s, Loss-threshold: 3 frames
     MEP identifier: 700, Direction: down, MAC address: 00:90:69:0b:4b:94
     MEP status: running
     Defects:
      Remote MEP not receiving CCM : no
      Erroneous CCM received : yes
      Cross-connect CCM received : no
      RDI sent by some MEP : yes
     Statistics:
      CCMs sent : 76
      CCMs received out of sequence : 0
      LBMs sent : 0
      Valid in-order LBRs received : 0
      Valid out-of-order LBRs received : 0
      LBRs received with corrupted data : 0
      LBRs sent : 0
      LTMs sent : 0
      LTMs received : 0
      LTRs sent : 0
      LTRs received : 0
      Sequence number of next LTM request : 0
      1DMs sent : 0
      Valid 1DMs received : 0
      Invalid 1DMs received : 0
      DMMs sent : 0
      DMRs sent : 0
      Valid DMRs received : 0
      Invalid DMRs received : 0
     Remote MEP count: 1
      Identifier   MAC address       State      Interface
       800         00:90:69:0b:7f:71 ok         ge-5/0/9.0

The advantage of CFM compared to LFM is the ability to monitor and troubleshoot the network end-to-end with CFM, rather than merely registering failed links as with LFM.