DHCP for PC and IP Phone - Best Practices

kfarrington · ‎07-12-2007

All,

Are there any best practices for DHCP for your devices on a data or voice VLAN.

i.e.

If I have data vlan of say, 10.10.10.0 /24 and I have a voice vlan of 10.10.11.0 /24

would it not be nice for troublshooting and design purposes to have the host portion as the same number?

ie, a PC would be 10.10.10.1 and the phone would be 10.10.11.1

Just a thought?

Dont think it can be done?

If anyone has any ideas on this, please could you be so kind to let me know.

Many thx

Ken

johnhsnow · ‎07-12-2007

HI Peter. It depends on the scope of your network but just to give you an example a contiguous block of Class B for voice and data might be something like this:

Data > 10.200.100.0 /24 - You can further subnet this into /24's based on need and size of network ie..

10.200.101.0

10.200.102.0

10.200.103.0

10.200.104.0

......

Voice > 10.201.100.0 /24

10.201.100.0

10.201.101.0

10.201.102.0

10.201.103.0

10.201.104.0

.........

You cannot assign host addresses if you are using DHCP but you have control over the scopes.

Hope this helps.

JS

kfarrington · ‎07-12-2007

Thx for the speedy response John.

I just thought it would be nice if you could do something with the host portion.

Lets say that an IP Phone gets an address of 10.201.101.1, then the DHCP server when assigning the IP address of the PC plugged into the back of the phone, could somehow inspect the IP address of the phone, and try and assign the last octet as the same for the PC as the phone.

Hairbrained I know, but would be a good little feature?

Just a thought? and many thx for the reply :)

Kind regards,

Ken

kfarrington · ‎07-12-2007

Also, the two DHCP scopes would have to be in sync, ie, if a phone had the address .1 but the PC was not turned on, the DHCP server would know that the .1 is assigned to a phone, and would not allocate the data DHCP address.

I dont know how this would fully work, as I say, a hairbrained idea I suppose

:))))))