Excessive Broadcast Traffic

[ashrobbo]

Hi All,

My google-fu is failing me.

I have a phone system (avaya ip406) that is broadcasting TFTP excessively. It does the odd broadcast occasionally which is normal, but theres an issue where it overloads all of our LAN switches, and will continue spitting out broadcasts packets every few milliseconds until we pull the lan cable for 5-10 mins. Our telecomms co. is suggesting we 'adapt' our network.

Now, they have suggested we VLan our switches.

We have 2 of these phone systems so they will need to exist on their own vlan. We have 1 phone system in each office, these 2 offices are joined by a single 100mb line.


Phone system 1 ---- Switch 1 ---- Cat5e>Fibre converter ----- Fibre converter>cat5e--- Switch 2 --- Phone system 2


Lets say port 48 on each switch is the phone system, and port 1 is the link between the two buildings.

I would need to Tag (procurve switches 4104gl and 2650) Port 48 in Vlan2 on each switch (to segment off from other network traffic) and I would need to tag Port 1 in both vlan 1 and 2 so both phone and data can travel across.

My question

Will vlanning stop the switches grinding to a halt? if the phone system kicks off would it still bring down our switches even though they are vlanned off?

I would have thought the scope of the broadcast would be reduced but its still sending thousands of broadcast packets to a switch in a very short amount of time thus overloading it. (switch cpu stays at 100%)

They are trying to cover up the issue rather then fix it but I wanted to give it a go even as a temporary solution.

Thanks,

Ash

 

[ashrobbo]

I'd have thought you would need to QOS the vlan to prevent switch contention, that will segregate the phone traffic and limit its saturation capability on the cross site links

for example with our cisco ip solution we had a ceiling level on the voip vlan and if it became saturated then the call manager server would drop codec levels to allow maximum potential calls

But will vlanning effectively stop the switch becoming overloaded? I understand it would have less of an affect on the actual Data network and not affect our current PXE TFTP servers. Even if our faulty phone system starts mass TFTP broadcasting I understand it will only be able to broadcast out of any ports tagged in the vlan.

But the amount of traffic that is surging through surely that will cause the switch to overload?

Im not sure out switches even have QOS on them.....