![]() ![]() If there is a Bridge Virtual Interface (BVI) in the bridge-domain, all incoming tags should be popped because the BVI is a routed interface without any tag.Use the rewrite command to modify the default. On a Cisco ASR 9000 Series Aggregation Services Router that uses the EVC infrastructure, the default action is to preserve the existing tags.On traditional routers that do not use the Ethernet Virtual Connection (EVC) model, the VLAN tags configured under the subinterface are removed (popped) from the frame before they are transported by the L2VPN feature.The incoming frame fails to match any other subinterface, so it matches the main interface that is configured for l2transport.The incoming frame fails to match any other subinterface, so it matches a subinterface configured with the encapsulation default command. ![]() The incoming frame has no dot1q tags and matches a subinterface configured with the encapsulation untagged command.The incoming frame has one or more dot1q tags and matches a subinterface configured with one of the dot1q tags.The incoming frame has one dot1q tag and matches a subinterface configured with the same dot1q tag and the exact keyword.The incoming frame has two dot1q tags and matches a subinterface configured with the same dot1q first tag and any for the second tag.The incoming frame has two dot1q tags and matches a subinterface configured with the same two dot1q tags (802.1Q tunneling, or QinQ).A longest match lookup determines the incoming interface of the packet. The longest match lookup checks these conditions in this order to match the incoming packet to a subinterface:.This interface can be a main interface, where the l2transport command is configured under the interface config mode, or a subinterface, where the l2transport keyword is configured after the subinterface number.A packet must be received on an interface configured with the l2transport keyword in order to be processed by the L2VPN feature.Hierarchical VPLS can be used in order to increase scalability:īasic rules for attachment circuits (ACs) include: ![]() Virtual Private LAN Services (VPLS) lets you extend the broadcast domain between multiple sites using MPLS PWs: ![]() Multiple switches can do traditional Ethernet switching spanning tree must be used in order to break loops: Multipoint service emulates a broadcast domain so that all hosts connected in that bridge-domain appear to be logically connected to the same Ethernet segment:Īll hosts can be connected to the same router/switch: Other designs are available, but cannot all be listed here. Redundancy is available through the PW redundancy feature: There can also be a Multiprotocol Label Switching (MPLS) pseudowire (PW) between two routers:Ī router can switch frames between two PWs in this case, this is a multi-segment PW: One router can do local switching between two of its interfaces: In reality, there can be multiple routers between the two end nodes, and there can be multiple designs to provide the point-to-point service. Point-to-point service basically emulates a transport circuit between two end nodes so the end nodes appear to be directly connected over a point-to-point link. The L2VPN feature provides the ability to provide point-to-point and multipoint services. See the Cisco ASR 9000 Series Aggregation Services Router L2VPN and Ethernet Services Configuration Guide, Release 4.3.x for additional information.ġ. It is useful to present basic examples in order to demonstrate design, services, features, and configuration. This document describes basic Layer 2 (L2) VPN (L2VPN) topologies. ![]()
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