Design Guide

Chapter 5 VPWS
CISCO ASR 9000 EFP MTU behaviour
• CISCO ASR 9000 INTELLIGENTLY adjusts sub-interface/EFP MTU
• If “rewrite pop” is configured, MTU size is reduced by the 4 bytes for each VLAN popped.
• If “rewrite push” is configured, MTU size is increased by 4 bytes.
PROBLEM : The VPWS will not come up due to MTU mismatch !
SOLUTION : Configure MTU manually on the EFP on CISCO ASR 9000 to match with the MTU size on
the remote side !
NOTE : Remember CISCO ASR 9000 takes L2 size on the MTU command.
CISCO ME3600X/3800X and CISCO ASR 903 Configuration
interface GigabitEthernet0/2/0
no ip address
negotiation auto
service instance 555 ethernet
encapsulation dot1q 100 second-dot1q 200
rewrite ingress tag pop 1 symmetric
xconnect 11.1.1.1 555 encapsulation mpls !
CISCO ASR 9000 Configuration
l2vpn
xconnect group vpws
p2p vpws
interface GigabitEthernet0/2/0/0.555
neighbor 121.0.1.1 pw-id 555
!
!
!
interface GigabitEthernet0/2/0/0.555 l2transport
encapsulation dot1q 100 second-dot1q 200
rewrite ingress tag pop 1 symmetric
mtu 1518