Pbb Technology; Figure 101: Ieee 802.1Ah Frame Format - Alcatel-Lucent 7750 SR Manual

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PBB Technology

IEEE 802.1ah specification encapsulates the customer or QinQ payload in a provider header as

PBB adds a regular Ethernet header where the B-DA and B-SA are the backbone destination and

respectively, source MACs of the edge U-PEs. The backbone MACs (B-MACs) are used by the

core N-PE devices to switch the frame through the backbone.

A special group MAC is used for the backbone destination MAC (B-DA) when handling an

unknown unicast, multicast or broadcast frame. This backbone group MAC is derived from the I-

service instance identifier (ISID) using the rule: a standard group OUI (01-1E-83) followed by the

24 bit ISID coded in the last three bytes of the MAC address.

The BVID (backbone VLAN ID) field is a regular DOT1Q tag and controls the size of the

backbone broadcast domain. When the PBB frame is sent over a VPLS pseudo-wire (pseudowire),

this field may be omitted depending on the type of pseudowire used.

The following ITAG (standard Ether-type value of 0x88E7) has the role of identifying the

customer VPN to which the frame is addressed through the 24 bit ISID. Support for service QoS is

provided through the priority (3 bit I-PCP) and the DEI (1 bit) fields.

7750 SR OS Services Guide

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Virtual Private LAN Services