Atm/Frame Relay Pvc Access And Termination On A Vpls Service; Figure 89: Atm/Frame Relay Pvc Access And Termination On A Vpls Example - Alcatel-Lucent 7750 SR Manual

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ATM/Frame Relay PVC Access and Termination on a VPLS Service

RFC2684/RFC2427

The application is depicted in above provides access to a VPLS service to Frame Relay and ATM

users connected either directly or through an ATM access network to a 7750 PE node. The 7750

SR supports a Frame Relay or an ATM VC-delimited Service Access Point (SAP) terminating on

a VPLS service.

RFC 2427-encapsulated or RFC 2684-encapsulated untagged Ethernet/802.3 frames (with or

without Frame Check Sequence (FCS)) or BPDUs from a customer's bridge device are received

on a given SAP over an ATM or Frame Relay interface on the 7750 SR. The Frame Relay or

ATM-related encapsulation is stripped and the frames (without FCS) are forwarded towards

destination SAPs either locally, or using SDPs associated with the VPLS service (as dictated by

destination MAC address VPLS processing). In the egress direction, the received untagged frames

are encapsulated into RFC 2427 or RFC 2684 (no Q-tags are added, no FCS in the forwarded

frame) and sent over ATM or a FR VC towards the customer CPE.

When AAL5 RFC2427/2684 encapsulated tagged frames are received from the customer's bridge

on an FR/ATM SAP, the tags are transparent and the frames are processed as described above with

the exception that the frames forwarded towards the destination(s) will have the received tags

preserved. Similarly in the egress direction, the received tagged Ethernet frames are encapsulated

as is (i.e. Q-tags are again transparent and preserved) into RFC 2427/2684 and sent over the FR/

ATM PVC towards the customer CPE. Note that since the tagging is transparent, the 7750 SR

performs unqualified MAC learning (for example, MAC addresses are learned without reference

to VLANs they are associated with). Because of that, MAC addresses used must be unique across

all the VLANs used by the customer for a given VPLS service instance. If a customer wants a per-

7750 SR OS Services Guide

APS Protected

Virtual Private LAN Services

Ethernet-MPLS

Ethernet (VLAN)