How to configure Cisco 2924-xl to use DHCP?

[onury]

Mýght be a simple and also threaded topic but I am a newbie here and need some serious help. We couldn't be able to configure a cisco 2924-xl of ours to get our DHCP servers giving ip leases to our clients. Is there anyone who could help us on this topic?

If this topic is already threaded in this board pls tell me so so that I can close the topic asap. Thanks in advance.

Onur Yildirim

 

[UNIX72]

Are you trying to give the switch a dynamic ip address or clients who are connected to the switch can't get a ip address? Well pertaining to the first question you shouldn't give the switch a dynamic address instead use a static ip for network management.

 

[Bluecrack]

You should use a static IP address on the switch itself. The clients connected to the switch should receive DHCP addresses just fine once the switch is configured.

 

[onury]

Thanks for all the replies.
We have fixed our problem but one challange is still ahead of us. Our main problem was that the client couldn't get their ip leases over a atatic ip switch because the ip of the DHCP server (in this case a Win2K server) was not present in the ip-helper address list of the switch. We set the right ip helper addresses and now it just works fine.
But now we have another problem. When the spanning tree is active, our PXE clients cannot connect to DHCP server and then to the Remote Installation Services. Now I have another question:

How much does the spanning tree option raise the performance of the switch?

Thanks in advance.

Onur Yýldýrým

 

[UNIX72]

Do you have spanning tree enable on all ports only should be use for ports that will provide redundancy. Try enabling spanning-tree portfast, which allows the port to go straight to forwarding mode.
NOTE: Only do this for END NODES, do NOT enable it on any port connected to another switch or router.
I don't see how ip helper address fix your problem but hey it work

 

[Bluecrack]

UNIX72 has a good point. Enabling "spanning-tree portfast" will allow the port to go directly into the forwarding mode. On ports without spanning-tree enabled, the port spends 15 seconds in learning and 15 seconds in listening mode so the port will not start forwarding traffic for at least 30 seconds. This is probably enough time for the PXE BIOS to time out.

Again, only enable portfast for those ports that are connected to end nodes.

Bluecrack

 

[Guest_imported]

How do I set password on the switch?

any other tips for configuring from sctratch?

 

[tuks]

I have a couple of those switches and we are moving to DHCP soon. Which interface will I enable ip helper address on ? Will it be on the management interface (Default VLAN 1) ?

 

[bierhunter]

Hmmm...I'm getting a little confused here. Unless our 2924XL's we have are old, I've never seen an IP Helper-address on them. I have seen it on the router if the DHCP server is in a different subnet from the clients. The IP helper-address is used to forward UDP broadcasts between subnets. A layer-2 switch isn't involved in that process. I haven't kept up to date on new models, so ..is there a layer-3 2900XL series out? If so, that would be nice to play with.

If the DHCP server is on the same subnet as the clients, then you really shouldn't have a problem. The clients will broadcast to find the DHCP.

Forcing the host ports into a Forwarding state with Portfast is definitely something you want to do. But as stated before...only on single host ports.

 

[Guest_imported]

use the spantree-portfast cmd...

chris