IBM Nortel Networks L2/3, Manual

Page: 109 / 190

Chapter 7. Nortel Networks L2/3 GbESM configuration and network integration
95
ip classless
ip route 0.0.0.0 0.0.0.0 9.42.171.3
ip http server
ip http secure-server
!
control-plane
!
line con 0
line vty 0 4
password cisco
no login
line vty 5 15
no login
!
end
7.7.3 Rapid Spanning Tree IEEE 802.1w
The GbESM supports the IEEE 802.1w RSTP (Rapid Spanning Tree) standard. When this
protocol is used there can be only one Spanning Tree Group. When IEEE 802.1s Multiple
Spanning Tree is used, multiple spanning tree instances can be configured. The
consequence of this is that VLAN 4095 (the Management VLAN) will be moved to Spanning
Tree Group 1, while Spanning Tree Group 16 (the STG for the Management VLAN) is turned
off if RSTP is enabled on the GbESM.
When GbESM modules were connected to switches that run Cisco Rapid-PVST, the
untagged (native) VLAN looped during our tests for this sample configuration. Because the
chosen topology (see Figure 7-5 on page 81) allows STP to be disabled on the BladeCenter
Switch Modules, Rapid-PVST was configured on the Cisco devices, and STP was switched
off completely (STG and MRST) on both GbESMs.
Prepare the Nortel GbESM_1 and GbESM_2 for Rapid Spanning Tree
Due to incompatibilities in the RSTP behavior of the GbESM and the Cisco 3560, Spanning
Tree is disabled on the GbESMs and Rapid-PVST is enabled on the Cisco Switches.
Remember to disconnect the devices before starting configuration changes as described in
7.5, “Base configurations for examples in this document” on page 66.
Ensure that Rapid STP is disabled:
/c/l2/mrst/off
Move all VLANs (except management VLAN 4095) to Spanning Tree Group 1 and switch it
off:
/c/l2/stg 1/add 1 5 10 20 99
/c/l2/stg 1/off
Configure the Cisco Core1 and Core2 for Rapid-PVST
Change the Spanning Tree mode from the default mode to Rapid-PVST:
conf t
spanning-tree mode rapid-pvst
In our example, we divide the Root Bridge over the VLANs to share the load, Core1 should be
the Root Bridge for VLANs 5 and 10:
spanning-tree vlan 1-10 root primary
spanning-tree vlan 11-4094 root secondary