The article explains steps followed to bring up a newly provisioned L2circuit/L2vpn which is down with status EM -- encapsulation mismatch
Topology
You may see L2circuit is down with status reported as EM -- encapsulation mismatch
root@PE2_RE> show l2circuit connections
Layer-2 Circuit Connections:
Legend for connection status (St)
EI -- encapsulation invalid NP -- interface h/w not present
MM -- mtu mismatch Dn -- down
EM -- encapsulation mismatch VC-Dn -- Virtual circuit Down
CM -- control-word mismatch Up -- operational
VM -- vlan id mismatch CF -- Call admission control failure
OL -- no outgoing label IB -- TDM incompatible bitrate
NC -- intf encaps not CCC/TCC TM -- TDM misconfiguration
BK -- Backup Connection ST -- Standby Connection
CB -- rcvd cell-bundle size bad SP -- Static Pseudowire
LD -- local site signaled down RS -- remote site standby
RD -- remote site signaled down HS -- Hot-standby Connection
XX -- unknown
Legend for interface status
Up -- operational
Dn -- down
Neighbor: 192.168.21.21
Interface Type St Time last up # Up trans
ae100.3150(vc 3150) rmt EM
The above issue is due to a configuration mismatch between PE Routers. You can see from the below configuration snippet that, PE1 has vlan-normalization rules applied but PE2 did not have similar configurations.
root@PE1_RE> show configuration protocols l2circuit
neighbor 192.168.23.23 {
interface ae100.3150 {
virtual-circuit-id 3150;
}
root@PE1_RE> show configuration interfaces ae100.3150
encapsulation vlan-ccc;
vlan-id 3150;
input-vlan-map pop;
output-vlan-map push;
root@PE2_RE> show configuration protocols l2circuit
neighbor 192.168.21.21 {
root@PE2_RE> show configuration interfaces ae100.3150
Correcting the configurations will help to resolve the issue
root@PE23_RE> show configuration interfaces ae100.3150
ae100.3150(vc 3150) rmt Up Feb 29 20:37:31 2024 1
Remote PE: 192.168.21.21, Negotiated control-word: Yes (Null)
Incoming label: 30, Outgoing label: 36
Negotiated PW status TLV: No
Local interface: ae100.3150, Status: Up, Encapsulation: ETHERNET
Flow Label Transmit: No, Flow Label Receive: No