vlan VoIP question

[CyberNerd]

Our bursar is looking at buying in a VoIP solution, I suspect that she is going to get a firm in to build another network on top of our existing network.

I'd like to see money spent on upgrading what we have, so the question is:

suppose two networks are separated by VLAN - one for VoIP and one for data - in the event of a hypothetical virus/network storm/error of some kind (most imaginable senarios) could the data network knock out the VoIP network ??

[andyrite]

It depends on your current network setup. You will need to look at QOS as well.

[Geoff]

suppose two networks are separated by VLAN - one for VoIP and one for data - in the event of a hypothetical virus/network storm/error of some kind (most imaginable scenarios) could the data network knock out the VoIP network ??

Only if the switches throughput/switching capability/routing table is exhausted. For example, a Procurve 2650 has a maximum rated throughput of 13.6Gbit/s, a maximum rated switching capability of 10.1 million packets/s and a maximum routing table size of 8000 entries.

As you approach these limits, the functionality of the switch will degrade. Normally starting with latency and packet loss, but ultimately ending in complete loss of the switch.

[CyberNerd]

ok, thanks.
I will try to convince her that money would be better spent adding resiliance and segregating teh network. I have a bad feeling that she's already determined on her course of action though.

[srochford]

I'd certainly want to go for 1 decent network rather than 2 not very good networks :-)

I'd guess you need to try and look at worst case scenarios. If someone does manage to generate enough traffic to take down your network, what would you do to recover? Could you live without phones while you did it? (If you're going VoIP, have you made plans for power cuts - no phones at all then and much more likely than network problems!)