MTU
Agree on the MTU with the other side. If one end sends larger frames than the path supports, some traffic will fail in ways that are hard to diagnose. Test with large pings after activation.
VLAN tags
On the fabric, each party’s VLAN tag only matters on its own port. You and your partner can use different VLAN IDs for the same VXC.
Addressing
Use small point-to-point subnets: /31 for IPv4 and /127 for IPv6 where supported, or /30 and /64 if not.
Routing
Run BGP over the VXC for dynamic routing and failover. Filter what you accept.
Failure detection
BFD speeds up detection of path problems.
Documentation
Record the circuit ID, VLANs, addresses, bandwidth and contacts for both sides. It saves time during incidents.
