DHCP Relay Problem with Avaya ERS5000 SW 6.3

I recently stumbled upon a problem with the Avaya ERS5000 switches. The problem was quiet odd , so I would like to share my expierence and hopefully help somone with troubleshooting this problem.

On a given network where a ERS5000 is the core switch and also did the L3 routing for the network I updated from SW 6.2.x to 6.3.4. In my case I had a switchclsuter the update process had worked probably and with a switchcluster for the users there was only a short second outage during the update process.  I made some test after the update and found out that the clients can not receive an address over the DHCP server anymore. With manual configured IP adresses everything worked fine, only DHCP was not working. The DHCP relay agents where configured and active on the ERS5000.

After digging into the release notes of SW 6.6 I found this documented issue:

In some previous software releases of the Stackable
ERS platforms (ERS 2500, 3500, 4000 and 5000
Series) as well as the VSP 7000, a software issue
was found to cause malformed DHCP packets as
they were forwarded out of the switch.
In the software releases listed in the preceding row,
a code change has been made to stop the
malformed packets from being generated and also to
discard these malformed packets if the switch is
receiving them.

Avaya recommands to upgrade the Acces switches wich are connected to the ERS5000 to resolve the issue.
The issue is related to the feature combination of DHCP relay agent and DHCP snooping or NonEapPhone Authetication.

Here are the the switches that have to be upgraded to resolve the issue:
• ERS 25xx: 4.4.3.
• ERS 35xx: 5.1.2, 5.2.x
• ERS 4xxx: 5.6.4, 5.7.1, 5.8.x
• ERS 5xxx: 6.2.8, 6.3.3, 6.6.x
• VSP 7xxx: 10.3.2, 10.4.x

So if you are planing to upgrade a ERS5000 that is using the DHCP relay agent feature take care that you also update the connected Access switches at least to the version mentioned above. The odd think about this issue is that the older 6.2.x code for the ERS5k works with the malformed DHCP packets without any issues.
In my case I had planed to update 2 core switches and ended with an Update 30+ accesswitches.

 

About Dominik

Network problem solver
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2 Responses to DHCP Relay Problem with Avaya ERS5000 SW 6.3

  1. Florian says:

    Hi,

    I like to have a new blog with informations especially about Avaya networking components.

    Thank you for the information about DHCP relay issues. I will take a look again if I get the next switch on my desk.

    Greets from Nürnberg to Berlin from a guy born in Berlin 😉

    Regards, Florian

    • Dominik says:

      Hi Florian,
      If you are looking for information around Avaya networking you come to the right place.

      Greetings to Nürnberg,
      Dominik

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