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Author Topic: Looking for advice on ARP problem between Avaya stack and Cisco  (Read 2217 times)

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Offline Brhodgins

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Looking for advice on ARP problem between Avaya stack and Cisco
« on: November 30, 2014, 01:21:46 AM »
Hi,

I'm having a strange problem that I can't seem to find an answer for by searching the forums. I have a remote ESXi host with 10 VMs on it, all on the same VLAN 132. It is connected via a TLS connection. Six of them are reachable, from my machine on VLAN5, four are not. When I remove the problem VMs' ARP entry from the Avaya stack, they come back. Briefly. I am doing all inter-VLAN routing through the stack. If I ping one of the problematic VMs from a local server on the same VLAN/subnet there is no problem. If I ping another IP on a different VLAN such as 136 or 200 from my local computer, again all is fine.
It's confusing because I ping a local machine on the 132 VLAN and some on the remote network. There is no firewall between me and the remote network in the Datacenter,
I know of two problems so far with the design, but I don't think they are the cause; the missing stack cable to complete the Avaya loop, and two switches believing that they are the root bridge (I think) for all VLANS - the 4548#1 (which I think it should be) and the second old Cisco 2950T that we use for printer connections.

I'm fairly new to Avaya equipment, maybe I have overlooked something, or more likely there is a better design for my network.
Being new to Avaya, I've been using the EDM, and since implementing some changes I'm finding it a lot slower than what I'm used to. I'm obviously doing something wrong. I am running RSTP on the Avaya switches and R-PVST on the Cisco switches.
I've attached the current topology..


Thank you,

B


Offline Brhodgins

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Re: Looking for advice on ARP problem between Avaya stack and Cisco
« Reply #1 on: November 30, 2014, 10:25:48 PM »
Can anyone please help?
I've been trying for hours to figure this out. I know it has something to do with the spanning-tree. I'll have people in the office in 9 hours, and I still have 4 unreachable servers.
I've emailed a support engineer at Avaya, but haven't heard anything yet.

Offline pat2012

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Re: Looking for advice on ARP problem between Avaya stack and Cisco
« Reply #2 on: December 02, 2014, 07:20:08 AM »
Hi Brhodgins.

The 2 switches believing that they are the root bridge could potentially be a problem. Also, the way the Cisco 2950's are connected is a concern.  What protocol are you using to connect between the 4548 stack and the Cisco's? You'll need some sort of trunking protocol such as LACP.

Since you have to remove ARP entries to get things working, I believe that the Cisco's and Avaya's are not talking properly on a Layer 2 level.