Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 280)

250 Multi-Service IronWare Switching Configuration Guide
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Overview
10
As with PB, PBB networks use a Spanning Tree Protocol (STP), e.g., RSTP or MSTP, to dynamically
determine the active topology of the PBB network and MAC address learning to dynamically build a
forwarding database. Since an IB-BEB forwards frames to PB and PBB networks, it has to learn
customer and backbone MAC addresses. However, since an IB-BEB is at the edge of the Service
Provider network, it only learns customer MAC addresses of the local traffic.
NOTE
When using ESI VLANs in the configuration, always configure the protocol in default VLAN.
IEEE 802.1ah Provider Backbone Bridging (PBB)
This section provides details on IEEE 802.1ah Provider Backbone Bridging (PBB), with a description
and a configuration example of an integrated PB and PBB network.
FIGURE 31 Integrated IEEE 802.1ad and IEEE 802.1ah network architecture
The Provider Backbone Bridge (PBB) protocol typically resides at the core of a carrier network,
interconnecting PB networks. Inside of a PBB network a carrier usually deploys PB systems for layer
2 interconnectivity. The PBB protocol is designed to insulate carrier infrastructure from having to
learn customer MAC addresses and provide a separation of service and networking components of
an Ethernet service provided to the customers:
• It provides IEEE 802.1ah encapsulation to add a backbone MAC header on the incoming PB
packet (which has customer DA or SA) so core carrier switches don't need to learn customer
MAC addresses.
• It supports creation of EVC (Ethernet Virtual Circuits) with a concept of an Ethernet Service
Instance (ESI), which is enabled by use of a globally unique 24-bit I-component Service
Identifier (ISID).
• PB packets are encapsulated with ISID, BVLAN, B-SA, and B-DA as shown in Figure 31 .
• Layer 2 switches in the IEEE 802.1ah-encapsulated network are normal PB systems, which
process BVLAN header as if it was an SVLAN-encapsulated packet.
• Tag-types: BVLAN and SVLAN tag-types are same (default 0x88a8), so the PB systems inside a
PBB network can process BVLAN packets as if they were SVLAN encapsulated.
802.1ad 802.1ad 802.1ah
PB
PB
PB PB
PBB PBB
CVLAN
SVLAN CVLAN
CVLAN
CVLAN CVLAN SVLAN
SVLAN ISID BVLAN B-SA B-DA
CPE
CPE