DHCP config in switch 2950

micro_xii · ‎01-19-2008

I have switch 2950.

My switch has a default vlan 1. What I want is to configure ports 1-16 that has a dhcp config. When a host is connected to the port, it will be given an IP automatically.

What is the configuration?

mahmoodmkl · ‎01-19-2008

Hi,

2950 is a layer 2 switch,DHCP cannot be configured on it. either u need a router or L3 capable switch for DHCP configuration.

Thanks

Mahmood

Jon Marshall · ‎01-19-2008

Hi

It's not clear exactly what you mean. There are 2 ways this could be read

1) You want the 2950 to act as a DHCP server and hand out IP addresses. if so i'm afraid you can't do this with a 2950 - see attached link for more detail.

http://www.cisco.com/en/US/docs/switches/lan/catalyst2950/software/release/12.1_22ea/SCG/swdhcp82.html#wp1148254

2) You have a separate DHCP server on a different subnet and you want clients in vlan 1 to get an IP address. If so you would need to use the "ip helper-address" command eg.

vlan 1

ip helper-address "DHCP server IP address"

HTH

Jon

Edison Ortiz · ‎01-19-2008

Can't do (2) either :)

Jon Marshall · ‎01-19-2008

Oh for crying out loud can't believe i did that. Not sure what i was thinking.

Edison is totally right 2 is not an option on a layer 2 switch such as the 2950.

Thanks Edison, there are times when i wonder if i should be offering advice to people !!

Jon

ankbhasi · ‎01-20-2008

Hi All,

Now I know people wont believe me here but you know 2950 can work as DHCP server but with some limitations as 2950 being layer 2 switch.

1) Multiple DHCP pools can be configured on a 2950 switch

2) A VLAN interface within the same subnet as the DHCP pool must be configured on the switch. Multiple VLAN interfaces (to match multiple DHCP pool ip subnets) can be configured

3) Only one VLAN interface can be active at any one time. The remainder of the VLAN interfaces will be Admin Down (by IOS)

4) Only one of the DHCP pools can be active at any one time. The pool that is active is determined by which VLAN interface is currently active

5) Only ports within the same VLAN as the active VLAN interface will be able to obtain an IP address from the locally configured DHCP pool on the 2950 switch.

So as the original post says it has vlan 1 and 1-16 ports are in vlan 1, 2950 can be configured as DHCP server for vlan 1 and pool can be configured and all machines in vlan 1 can get an ip address from active pool which will be for vlan 1 subnet.

Worth giving a try!!

HTH

Ankur

*Pls rate all helpfull post

Edison Ortiz · ‎01-20-2008

Ankur,

I'm sure TAC will send you their best regards for giving such advice :)

__

Edison.

Edison Ortiz · ‎01-20-2008

Jon,

Don't be too harsh on yourself. 99.9% of the time you are dead-on, how many times have you corrected me ? :) BTW, it's time for you to get your CCIE!

glen.grant · ‎01-20-2008

If you can't get it to work this may be why . This is out of one of the config docs on CCO.

Note The DHCP server feature is only available on Catalyst 2955 switches.