Service Provider & MPLS
L2VPN & VPLS
Carrying layer 2 itself across an MPLS core: point-to-point pseudowires that extend an Ethernet segment between two sites, and VPLS, which makes a whole provider network behave like one big switch — plus the EVPN successor that fixed both.
- read in order, or dip in
- 2 chapters
- updated 31 Aug 2026
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read in order, or dip in
updated 31 Aug 2026
Contents
- 01Pseudowires and EoMPLS: Point-to-Point L2VPNA pseudowire emulates a point-to-point layer-2 circuit over MPLS: the ingress PE takes entire Ethernet frames from an attachment circuit, pushes a pseudowire label (negotiated by targeted LDP between the PE loopbacks) plus a transport label, and the egress PE replays the frames onto the far attachment circuit. The provider moves frames without ever routing the customer's traffic — the customer keeps layer 2 end to end.
- 02VPLS: The Provider Network as One Big SwitchVPLS extends pseudowires from point-to-point to multipoint: each PE in a VPLS instance holds a virtual switching instance that MAC-learns like a bridge, connected to every other PE by a full mesh of pseudowires, with split horizon over the mesh preventing loops. The provider network behaves as one LAN for the customer — and inherits a LAN's problems at provider scale, which is what EVPN was created to fix.
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