3550-12G and dhcp, and a vlan Q

Bojan Zivancevic · ‎09-08-2004

1. Can 3550-12G be used as a DHCP server?

2. If it can, then I'm in trouble. :) The previous network configuration was created in such a way that one Windows server with two LAN cards was a DHCP server. This DHCP server was issuing addresses for both networks connected to it through the use of superscopes. Now, the idea is to get rid of the Windows server, connect both networks to the L3 switch and use a DHCP server built in the L3 switch.

Is it possible? I guess I will have to make two VLANs and use subinterfaces? The problem is that I must continue to use two separate networks because there is not enough addresses in one network. Also, IP readdressing is out of the question because this is an order straight from the top - no arguing about that.

I guess it could be done. What are the typical problems that could arise in such a configuration?

Georg Pauwen · ‎09-08-2004

Hello,

the 3550-12G comes with the Enhanced (EMI) Image and supports the DHCP server functionality. You could use Layer 3 VLAN interfaces, or use two of the Gigabit ports as routed ports (with the 'no switchport' command) and assign IP addresses from both ranges to those ports, which then would function as the default gateways for the respective network address ranges.

HTH,

GP

Bojan Zivancevic · ‎09-08-2004

Look, currently 3550 is used like an ordinary L2 switch, with Vlan1 address 10.80.1.11/24. These two nets I mentioned are 10.80.1.0/24 and 10.80.2.0/24 (currently these are separated by a windows server). Every port on the switch is populated. If I use two ports as routed ports, what should I do with the rest of the ports? If they stay in the Vlan1, should I remove the 10.80.1.11 address from it and put this adress on the first routed port? Then, put one address from the second net on the second routed port. If these other swichports can't stay in vlan1, what should I do?

BTW, I was 99% sure that 3550-12G has DHCP server feature because I tried to enter "ip dhcp pool" command and it worked. But, when I entered the EXACT IOS name in the Cisco Feature Navigator, it didn't say anything about dhcp at all! And when I tried the same thing with IOS-es from the 803 and 1721, FN returned properly that these IOS-es have DHCP server feature in them.