I am discovering MPLS configuration on Cisco ASR920, and for almost any "thing" that can be configured, there is often two or more ways to do it. For example, given this configuration:
interface pseudowire40 encapsulation mpls signaling protocol ldp neighbor 22.214.171.124 40 ! interface GigabitEthernet0/0/1 no ip address negotiation auto service instance 30 ethernet encapsulation dot1q 30 rewrite ingress tag pop 1 symmetric ! service instance 40 ethernet encapsulation dot1q 40 rewrite ingress tag pop 1 symmetric ! service instance 50 ethernet encapsulation dot1q 50 rewrite ingress tag pop 1 symmetric xconnect 126.96.36.199 50 encapsulation mpls ! ! l2vpn xconnect context vlan-30 member GigabitEthernet0/0/1 service-instance 30 member 188.8.131.52 30 encapsulation mpls ! l2vpn xconnect context vlan-40 member GigabitEthernet0/0/1 service-instance 40 member pseudowire40
There are three pseudowires configured, differently, and they all end up doing the exact same thing. I read most of the documentation regarding the ASR920 on Cisco's web site, and I am left with a feeling that I have no idea of the differences between those three configurations. And in the end, which I should go with, and why, so that we can kept all our configurations coherent, with the least exceptions possible.