May 07

Do you read the release notes for software updates?

Over the past years I have meet many people and watched how they pick their software for their network equipment. Sometimes they pick a good version and other times, it’s crash and burn. Learning from past co-workers I have learned to always read the release notes for that software version.

Sometimes the release notes are a few hundred pages, so I sift through every single page. I try to pick out the parts that apply to me and skip the rest. There are a few things that I look for when I read through the release notes.

Things I look for when reading the release notes of a new software version

1. Compatibility with my hardware.
– Will all of my line cards work?
– Do I have enough memory?
– Are all of my Wireless Access Points supported?
– Are all of my IP Phones and voice gateways supported?
2. Are there incremental upgrades, or can I go directly to this version?
3. What are the new features that may relate to me?
4. What configuration changes have been made
– Cisco ASA 8.3 code is a great example of this. NAT Completely changed in this version.
5. What are the known caveats? Do they apply to me and my hardware?
6. If I’m upgrading to resolve a Bug, is that bug listed? Is it in the list of resolved caveats?
7. Any performance information to be learned?
8. Upgrade directions

Through reading the release notes I have found some very interesting things, Below I have listed a few of them.

– I have to start this off with the Cisco ASA 8.3 release notes. Cisco changed the way NAT was used. This was a major change and Cisco dedicated many pages in the release notes to the new changes. If I wouldn’t have read the release notes the upgrade would have been a disaster.

– There was a version of software for one of the routers we use that didn’t really encrypt the IPSEC packets. Moved on to the next release and made sure that caveat was resolved, it was.

– I was going to upgrade to be able to add a new line card. I found out that the line card wouldn’t run as many line rate ports if there were specific types of line cards in the chassis. We had those line cards, so the number of line rate ports went way down. This was disappointing, but better to find out now then a year later when customers were complaining of slow connections.

– Where to place the OS file to get it to boot? It will tell you. I failed to look and turned my device into a brick. Now I always read where to put the software on the device.

– The Brocade MLXe is not a simple device to upgrade. There are multiple files that need to be copied to the management modules and then again to the line cards. The release notes spell it all out and make it a lot easier then what it seems.

What wild and crazy things have you found by reading the release notes?
What have you broke because you didn’t read the release notes?
Tell us about your stories about reading or not reading the release notes

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


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