Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 400)

370 Multi-Service IronWare Switching Configuration Guide
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MSTP support for PBB
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• MSTP should not be configured for (1) topology groups having layer 2 (L2) member VLANs (2)
member VLANs configured in a topology group. If a topology group is configured with a master
vlan running MSTP, layer 2 (L2) VLANs should not be configured as members until MSTP is
disabled on the master VLAN of this topology group. Such configurations via CLI are blocked.
Use case scenario
Figure 68 displays the use case. In this scenario, the network has two Core Switches (CSs) to
provide resiliency in the core as well as service load sharing.
The CS functions as a Backbone Core Bridge (BCB). Every AS (Access Switch) in the network will
dual home to the two CSs. The AS functions as a Backbone Edge Bridge (BEB). The function of the
CS is to switch traffic between ASs. As a BCB, a CS will switch on the outer PBB B-tag and will not
perform any PBB encapsulation.
The AS accepts 802.1q, or Q-in-Q traffic, from ESs and encapsulates the traffic into PBB frames.
The SVLAN of the customer frame is the service delimiter and is mapped to a specific ISID in the
PBB network. The ASs are logically interconnected with PBB tunnels (BVLANs), which always
traverse a CS. The ASs will connect to the ESs as shown in
Figure 68 .
The AS and CS switches in a network will form a single MSTP region. With the dual homing of the
ASs to the CSs, all failures are protected against.
Each ES will attach to an AS and will form its own MSTP domain with the AS as the root. ES traffic
that is destined for a port on the same ES does not need to enter the network core. The traffic will
stay intra-switch.
Traffic that is destined for a port on another ES attached to the same AS will switch directly on the
AS and will not have to enter the network core. The traffic will stay within the AS and attached ES.
Traffic that is destined for a port on an ES that is attached to a different AS will be encapsulated
into PBB and will traverse the PBB core.
FIGURE 68 Ethernet Switch Architecture Use Case