IP telephony IP-addressing

[admin_2]

Two, three months from now we have decide to implement IP telephony on our LAN. Our LAN is IP tel ready all inline power and the latest hardware 6513 and 3548 and software releases. But we still don 't know what direction we will go with our IP addressing for IP telephony. Today we use Class C addresses for our PC ‘s (+/- 800) and separate VLAN according the location within our plant. Our intention is to use also CLASS C addresses for VVID and create different vlans for voice depending on the location within our plant. Is this a good idea or is it better to use class B addresses? Total no of phones is 700. What are advantages/disadvantages in class B or C for voice. E.g. 172.29.201.0/24 for servers and gateways, 172.29.205.0/24 for ADMIN to 172.29.210.0/24 for the last location.

[#2]

You total number of ip phones would 700 as mentioned

in your question, so class C address wont scale up to 700.

1. Class C only has about 254 host addresses posible and even less

when you subnet.

2. Class B has a whole lot more.

You can then subnet the class B network to how much is needed per vlan.

[gary.shaw]

Why dont you use a private addressing scheme for your phones, you dont have to worry then and its better from a security point of view.

Gary

[shoudek]

I wouldn't recommend using private addressing unless you don't have the address space. While it may be more secure, you're making a very short term decision by doing so. You're making the assumption you'll never need to route this traffic which isn't realistic given the end game for all of this is 100% packet based telephony. Do you really want to be forced to nat or proxy all this stuff when we're getting IP pipes from ISP's for telephone calls?

I completely disagree with Cisco's design guide recommending you pursue this scheme. You're