NEXUS DC · L2VPN

Nexus: point-to-point pseudowire (xconnect)

PC1 and PC2 share one subnet, 192.168.100.0/24, but sit on opposite sides of an MPLS core. IS-IS and LDP already run on PE1, P and PE2. Build a pseudowire between PE1 and PE2 with VC ID 100: every frame entering a customer port leaves the customer port at the far end, as if the core were one long cable.

Nexus DC track · Cisco Nexus (NX-OS-style) · 4 objectives

Open in simulator More Nexus DC labs

Objectives

The simulator ticks each one as soon as the network meets it.

On PE1, attach the customer port Ethernet1/2 to a pseudowire toward 2.2.2.2 with VC ID 100.
On PE2, do the same toward 1.1.1.1 with VC ID 100.
The pseudowire is up on both PEs (show l2vpn atom vc).
Ping 192.168.100.2 from PC1: the hosts see one Ethernet segment.

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Before you start

On NX-OS the pseudowire is an interface of its own (interface pseudowire 12), and l2vpn xconnect context joins it to the service instance. On real hardware this is a Nexus 7000/7700 feature. A pseudowire peers with the far PE’s loopback, the VC ID must match on both ends, and a label path must run both ways.

Concept

Pseudowires: Ethernet through an MPLS core

A pseudowire makes an MPLS core look like one long cable between two customer ports, called attachment circuits. The ingress PE pushes two labels on each frame: an inner VC label that names the far attachment circuit, and an outer transport label that carries it across the core. LDP signals the VC label between the two PEs, directly, through a session that may cross many routers.