Question

A service provider engineer configures a point-to-point EoMPLS (VPWS) pseudowire between two IOS XR PE routers using the l2vpn xconnect group. The attachment circuits are up on both PEs and the targeted LDP session is established, but the pseudowire remains in the DOWN state. On PE1 the interface MTU under the attachment circuit is set to 1500, while on PE2 the corresponding attachment circuit interface MTU is set to 1600. What is the most likely reason the pseudowire fails to come up?

Accepted Answer

The interface MTU values signaled in the LDP label mapping messages do not match, so the pseudowire negotiation fails

Answer

The control word setting is enabled on PE1 but disabled on PE2, causing a signaling mismatch

Answer

The pseudowire IDs (VC IDs) are different on the two PEs, so the label bindings cannot be paired

Answer

The route distinguishers configured under the xconnect group differ between the two PEs