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Nokia VPLS study materials
Nokia VPLS study resources

Nokia VPLS: VPLS fundamentals and architecture

Nokia VPLS · Work through your exam, one topic at a time.

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VPLS fundamentals and architecture

Domain 1 tests VPLS fundamentals and architecture: the multipoint service model, how Nokia SR OS represents a VPLS, and how the data plane behaves.

Service model

  • A VPLS is one Layer 2 broadcast domain extended over an MPLS network. The customer sees one LAN; the PE learns customer MAC addresses per VPLS instance.
  • In Nokia SR OS, the service object is vpls <service-id> under a customer <customer-id>. Local attachments are SAPs; remote attachments are SDP bindings, each a pseudowire.
  • Auto-discovery uses a VPLS ID, route distinguisher, and route target; LDP commonly signals the pseudowires. The service ID is local; the VPLS ID and RT must be coordinated across PEs.

Data plane rules

  • Unknown unicast, broadcast, and multicast are flooded to local SAPs and eligible SDP bindings. Source MACs are learned in the VPLS FDB and age out.
  • Split horizon: a frame received on a mesh SDP is not forwarded to another mesh SDP. It can still go to SAPs and spoke SDPs. This prevents forwarding loops in a full mesh.
  • VPLS is not VPWS: VPWS is point-to-point, while VPLS gives any-to-any multipoint connectivity.

Worked example

PE1 has SAP 1/1/1:100 and mesh SDP binding 2:100 to PE2; PE2 has SAP 1/1/1:100 and mesh SDP binding 1:100 back to PE1. CE-A broadcasts. PE1 floods to its SAP and the mesh PW. PE2 receives it, learns CE-A's MAC on the mesh binding, and forwards to its SAP. If PE1 had a second mesh SDP to PE3, the frame from PE2 would not be sent to PE3 because of split horizon; PE1 must rely on PE2-PE3 mesh connectivity for that path.

Traps

Do not confuse the SDP transport tunnel with the pseudowire; do not expect mesh-to-mesh flooding; do not treat service ID and VC ID as the same; and remember that split horizon applies to mesh SDPs, not local SAPs.