[j-nsp] L2VPN MTU Issue

[Eric Van Tol]

Hi all,
I'm having an issue with an L2VPN customer at the moment. They need to be able to pass 1500-byte IP packets between two locations connected via an ethernet encapsulated L2VPN.  I am able to ping from PE to PE with 1500-byte sized packets with the df-bit set without a problem.  The L2VPN connection is up and the customer can get a max of 1490-bytes through without fragmentation.  My LSP shows an MTU of 1500:

x.x.x.47
  From: x.x.x.46, LSPstate: Up, ActiveRoute: 0
  LSPname: xx_to_nn, LSPpath: Primary
  Suggested label received: -, Suggested label sent: -
  Recovery label received: -, Recovery label sent: 302048
  Resv style: 1 FF, Label in: -, Label out: 302048
  Time left:    -, Since: Tue Sep 28 12:35:29 2010
  Tspec: rate 0bps size 0bps peak Infbps m 20 M 1500
  Port number: sender 5 receiver 19901 protocol 0
  PATH rcvfrom: localclient 
  Adspec: sent MTU 1500
  Path MTU: received 1500
  PATH sentto: x.x.x.131 (ge-1/3/0.0) 217 pkts
  RESV rcvfrom: x.x.x.131 (ge-1/3/0.0) 215 pkts
  Explct route: x.x.x.131 x.x.x.121 x.x.x.5 x.x.x.58 x.x.x.164 
  Record route: <self> x.x.x.131 x.x.x.121 x.x.x.5 x.x.x.58 x.x.x.164  
Total 2 displayed, Up 2, Down 0

All interfaces *between* the PEs have the following config: IP MTU = 1500, MPLS MTU = 1512.  I have verified that the customer can hit their respective site's PE with 1500-byte packets by temporarily configuring each customer-facing interface with an appropriate IP address and pinging.

Here's the pertinent configs of the two PEs:

Side A:

interfaces {
    ge-0/0/1 {
        description "Site A";
        enable;
        mtu 9192;
        encapsulation ethernet-ccc;
        unit 0 {
            family ccc;
        }
    }
}
protocols {
    rsvp {
        interface ge-0/0/0.0;
    }
    mpls {
        label-switched-path xx_to_nn {
            to x.x.x.46;
        }
        interface ge-0/0/0.0;
        interface ge-0/0/1.0;
    }
    ldp {
        interface ge-0/0/0.0;
    }
}
routing-instances {
    cid-A {
        instance-type l2vpn;
        interface ge-0/0/1.0;
        route-distinguisher x.x.x:3211;
        vrf-import vpn-A-import;
        vrf-export vpn-A-export;
        protocols {
            l2vpn {
                encapsulation-type ethernet;
                no-control-word;
                interface ge-0/0/1.0;
                site Side-A {
                    site-identifier 1;
                    interface ge-0/0/1.0 {
                        remote-site-id 2;
                    }
                }
            }
        }
    }
}


Side B:
interfaces {
    fe-0/2/1 {
        description "Site B";
        enable;
        mtu 9192;
        encapsulation ethernet-ccc;
        unit 0 {
            family ccc;
        }
    }
}
protocols {
    rsvp {
        interface ge-1/3/0.0;
    }
    mpls {
        label-switched-path nn_to_xx {
            to x.x.x.47;
        }
        interface ge-1/3/0.0;
        interface fe-0/2/1.0;
    }
    ldp {
        interface ge-1/3/0.0;
    }
}
routing-instances {
    cid-A {
        instance-type l2vpn;
        interface fe-0/2/1.0;
        route-distinguisher x.x.x:3211;
        vrf-import vpn-A-import;
        vrf-export vpn-A-export;
        protocols {
            l2vpn {
                encapsulation-type ethernet;
                no-control-word;
                interface fe-0/2/1.0;
                site Side-A {
                    site-identifier 1;
                    interface fe-0/2/1.0 {
                        remote-site-id 2;
                    }
                }
            }
        }
    }
}

Does anyone see a problem with my configs here?  I seem to be losing 10 bytes somewhere and it's driving me mad. 

-evt