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Ethernet over MPLS for the Cisco 7600 Series Internet Routers
Feature History

Release 12.1(8a)E 12.1(8a)EX 12.1(11b)E 12.1(11b)EX1 12.1(13)E1

Modification This feature was introduced. Introduced support for EoMPLS on the optical services modules (OSMs). Introduced support for EoMPLS on the WS-X6182-2PA FlexWAN. Introduced support for 802.1Q Tunneling with EoMPLS. Introduced support forProtocol Tunneling with EoMPLS.

This feature module describes the Ethernet over Multiprotocol Label Switching (MPLS) feature, which transports Layer 2 VLAN packets across an MPLS backbone. This document contains information about the benefits of Ethernet over MPLS (EoMPLS) and lists supported platforms. It also provides configuration tasks, examples and related commands. This document includes thefollowing sections:
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Feature Overview, page 2 Supported Platforms, page 5 Supported Standards, MIBs, and RFCs, page 5 Prerequisites, page 6 Configuration Tasks, page 6 Configuration Examples, page 14 Command Reference, page 18

Cisco IOS Release 12.1E

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Ethernet over MPLS for the Cisco 7600 Series Internet Routers Feature Overview

Feature Overview
This feature allowsyou to connect two VLAN networks that are in different locations, without using expensive bridges, routers, or switches at the VLAN locations. You can enable the MPLS backbone network to accept Layer 2 VLAN traffic by configuring the label edge routers (LERs) at the both ends of the MPLS backbone. Adding a point-to-point virtual circuit (VC) requires you to configure the two VC endpoints at thetwo label edge routers. Only the two LERs at the ingress/egress points of the MPLS backbone know about the VCs dedicated to transporting Layer 2 VLAN traffic. All other routers do not have table entries for the VCs dedicated to transporting layer 2 VLAN traffic.

Benefits
As Internet service providers (ISPs) begin to deploy IP/MPLS backbones, services including frame switching must be supported.The Ethernet over MPLS feature allows an ISP to transport Layer 2 VLAN frames over an MPLS backbone.

Restrictions
The following services are not supported with the Ethernet over MPLS feature:
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Fragmentation and Reassembly: Because Ethernet over MPLS does not allow packets to be fragmented and reassembled, ensure that the maximum transmission unit (MTU) of all intermediate links betweenendpoints is sufficient to carry the largest Layer 2 VLAN cell received. Address Format: When OSPF is used as the IGP, all loopback addresses on PE routers must be configured with 32-bit masks to ensure proper operation of MPLS forwarding between PE routers. Packet Format: EoMPLS supports VLAN packets that conform to the IEEE's 802.1Q standard. The 802.1Q specification establishes a standard methodfor inserting VLAN membership information into Ethernet frames. Preserving 802.1 P bits and IP precendence bits: In order to preserve both 802.1q P bits and IP precedence bits, disable QoS globally. Once the QoS is enabled on a Layer 2 port, either 802.1q P bits or IP precedence bits can be preserved with the trusted configuration. However, the unpreserved bits are automatically overwritten bythe value of preserved bits. For instance, If you preserve the P bits, the IP precedence bits are overwritten with the value of the P bits. Private VLANs: EoMPLS is not supported with private VLANs. VLANs for EoMPLS: For POS cards, the maximum number of VLANs used for EoMPLS is 1005. Converting to a Previous Release of EoMPLS: To use a previous release of EoMPLS, first remove the following commandfrom your saved configuration commands: mpls label range Layer 2 Connections: The following restrictions apply to using Layer 2 connection with Ethernet over MPLS:
– You cannot have a direct Layer 2 connection between PEs with Ethernet over MPLS. – You cannot have more than one Layer 2 connection between routers if those routers are

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configured to transport Ethernet...