V-283824

Discussion

VPWS is a layer 2 virtual private network (L2VPN) technology that provides a virtual circuit between two PE routers to forward layer 2 frames between two customer-edge routers or switches through an MPLS-enabled IP core. The ingress PE router (virtual circuit head-end) encapsulates Ethernet frames inside MPLS packets using label stacking and forwards them across the MPLS network to the egress PE router (virtual circuit tail-end). During a virtual circuit setup, the PE routers exchange VC label bindings for the specified VC ID. The VC ID specifies a pseudowire associated with an ingress and egress PE router and the customer-facing attachment circuits. To guarantee that all frames are forwarded onto the correct pseudowire and to the correct customer and attachment circuits, the correct VC ID must be configured for each attachment circuit.

Check Content

Review the ingress and egress PE router configuration for each virtual circuit that has been provisioned and verify the correct and unique VCID has been configured for the appropriate attachment circuit.

Use the following command to verify "SvcId" and "VCID" fields and confirm the correct VC ID has been configured for the correct service, as shown in the example below: 

- show router ldp bindings services | match "VCId" post-lines 5

Type                                          VCId       SDPId             LMTU
Peer                                          SvcId      IngLbl            RMTU
                                                         EgrLbl
-------------------------------------------------------------------------------
E-Eth                                         10         40                1500
4.4.4.4:0                                     10         524282U           1500

Note: Ethernet over MPLS in VLAN mode transports Ethernet traffic from a source 802.1Q VLAN to a destination 802.1Q VLAN over a core MPLS network. The VC ID must be unique and the same on each end as it is used to connect the endpoints of the VC.

If the correct VC ID has not been configured on both routers, this is a finding.