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New Member

IP HELPER QUESTION

Here's my config:

interface Vlan60

ip address 170.208.115.2 255.255.255.0 secondary

ip address 10.8.132.2 255.255.255.0 secondary

ip address 10.2.164.2 255.255.252.0

ip helper-address 10.164.16.20

ip forward-protocol udp

I've got debug ip udp turned on. I do not see the BOOTPC messages being forwarded. I see netbios being forwarded alright, but no DHCP requests.

The SECONDARY interfaces shouldn't make a difference?

A PC trying to get an IP address doesn't know what subnet he's on.

Whats wrong with this picture?

Frank

5 REPLIES
New Member

Re: IP HELPER QUESTION

Frank

The Secondary interfaces should not make a difference. I have had the same set up before with secondary ips and had no problem. The ip helper-address command forwards eight UDP ports by default in which BOOTP server port 67 and BOOTP client (BOOTPC) port 68 are two of the eight. So I'm safe to say that a PC set up for DHCP never gets an address.

New Member

Re: IP HELPER QUESTION

>>>...So I'm safe to say that a PC set up for DHCP never gets an address.

Sorry, I don't know what that means. DHCP uses BOOTP to get an address from a DHCP server.

Frank

New Member

Re: IP HELPER QUESTION

hi,

Check if there are any access-lists configured on the L3 switch/ Router.Hope that there is no problem with the PC.

New Member

Re: IP HELPER QUESTION

Hi Frank,

It may be worthwhile putting a sniffer on the network at the PC or the DHCP server to see what you are getting.

Regards Brett

New Member

Re: IP HELPER QUESTION

Check the logs on the DHCP box to see if the request ever made it, both nix and winblows boxes log by default.

Later

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