Apr 16

Connecting Brocade switches to Cisco switches using PVST and PVST+

In order to get a Brocade switch to work well with a Cisco Switch while using PVST/PVST+, there is a little bit of extra configuration to do on the Brocade switch.

Per VLAN Spanning Tree (PVST) is a Cisco proprietary protocol that allows a Cisco device to have multiple spanning trees. The Cisco device can interoperate with spanning trees on other PVST devices but cannot interoperate with IEEE 802.1Q devices. An IEEE 802.1Q device has all its ports running a single spanning tree. PVST+ is an extension of PVST that allows a Cisco device to also interoperate with devices that are running a single spanning tree (IEEE 802.1Q).
The PVST+ support allows the device to interoperate with PVST spanning trees and the IEEE 802.1Q spanning tree at the same time.

If you are not familiar with Brocades configuration, you may want to click here to take a look at some more configuration examples. It’s a little different then Cisco, but not much.

Here you will see the configuration of a Brocade TurboIron connecting to a Cisco Catalyst 6500 using a trunk port (802.1q).

Brocade TurboIron Config

default-vlan-id 3999

vlan 2 name SERVER-VLAN by port
tagged ethe 2
spanning-tree 802-1w

vlan 3 name USER-VLAN by port
tagged ethe 2
spanning-tree 802-1w

interface ethernet 2
port-name To the Cisco Catalyst
dual-mode 1 —> VLAN 1 to match the native vlan of the Cisco
ip-port-mtu 1500 —> Set your MTU to match the Cisco’s MTU on that port
spanning-tree 802-1w admin-pt2pt-mac
pvst-mode —> Tells the switch to use PVST-MODE on this port only

Cisco Catalyst 6500 Configuration

vlan 2
vlan 3

interface TenGigabitEthernet9/5
description To the Brocade FastIron
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 2,3
switchport mode trunk

Here is an example of how you can view what ports on the Brocade Switch are running PVST Mode.

SSH@Goat-Switch#show span pvst-mode
PVST+ Enabled on:
Port Method
2 Set by configuration —> This port is in PVST-Mode due to an interface configuration
4 Set by auto-detect —> This port is in PVST-Mode because it auto detected it

Reference: http://www.brocade.com/downloads/documents/html_product_manuals/BIRX_02900a_CFG/wwhelp/wwhimpl/common/html/wwhelp.htm#href=STP.14.4.html&single=true

What problems have you had with interconnecting Brocade switches with Cisco Switches?
If you had a problem, what did you do to resolve it?