Later this month I will be installing an OS7400 with 120 VOIP phones. There will be no TDM phones. The voice and data networks will be completely separate. The switches will be 24 port POE gigabit switches, 9 total as they want to heat up all voice ports, configured in a daisy chain. What I want to know is how many switches can be in a daisy chain before we should consider a core switch setup. Nine switches seems like too many, but I really don't know. Any thoughts?

Why do they want them daisy-chained?

I know of no limit, however... when daisy-chained together, each switch has to process the network packets. So each switch introduces some latency in the complete chain.

No reason for the daisy-chaining, someone just assumed that is how they should be installed. We are responsible for just the switch and phones and are being handed the "network". My feeling is the ideal situation would be a core switch for this setup. Just wondering if I should be worried about this large of a stack.

I guess it depends on the latency specs of the switches you are planning to use. If an average switch adds less than a millisecond, then a phone on the the last switch will have less than 9 milliseconds added to it. Not really an issue in my mind, but I would be finding out the specs for the switches just in case they are much higher than that.

Why not one central NON poe switch. The remainders connected to it. Three hops is what I have always been told "no more than three hops"

Seacomms, I'll have to check the specs and find out. They are going to be Samsung iES4024GP's, not sold much here in the U.S. It's been hard to find specs on them but from what I've read so far they seem to be designed with VOIP in mind.

WRichey, that's exactly the idea behind a core switch setup. And if the OS7400 system is also connected to the core, only one hop from phone to switch.

My previous comment aside, I agree with that configuration too, why add more hops than necessary?

Daisy chaining switches is a bad idea (as each switch only has the bandwidth of the port that is daisy chained, so the last switch will have say 100/1000mbit to the switch previous in line, and that switch will only have 100/1000mbit to the previous switch and so on), unless they mean stacking but even then without management your going to get a similar situation.

Though since its only VoIP traffic which isn't very bandwidth intensive (compared to other data traffic, such as windows network/email).

I would recommend a core switch with the others "hanging off it", ideally managed switches so that ports can be configured as stacking ports.