miwitte wrote:
I have always stuck with /24 or /23 for the data and voice vlans which gives about 250/500 hosts per subnet. I saw some avaya docs that said that if using a a PC in back of a phone you should go no more than 250 hosts and use 100MB. This was a few years ago and now with newer PC's, 1GB NICS, and seperate voice and data vlans a /23 should not be a issue correct?
Reason is that I have a customer that has Nortel gear with /23's everywhere. We are rolling out 3750X and 2960-S and sticking with /23 would make for a much easier migration. Also we are setting up voice vlans as they are going VOIP(probably Nortel) soon as well so I would like the data and voice vlans to match say like data vlan 26 10.10.26.0/23 and voice vlan 226 10.10.226.0/23.
I know back in the day you were not supposed to have more than 200 windows hosts per subnet, but that was in the days of 10mb NICS and slow procs and like windows 95 or NT4.0...
I have never seen anything current about recommended hosts as its more dependant on the OS than the switching infrastructure.
It's primarily to do with broadcasts/multicasts (if you haven't enabled multicast routing) within the vlan(s) that matters more than the speed of the NIC. And for that there is no one size fits all because each company may run specific apps. Me, i always used either /24s or /25s but that doesn't mean that a /23 won't work.
If you don't have any major broadcast issues currently /23s should be okay.
Edit - just to note, there are other reasons for using smaller subnets such as virus containment etc. that may make using /24s or /25s more desirable.
Jon
