Testing DHCP Relay

[davidhuynh5]

We are constantly having DHCP problems on our network.  The problem is not with the network tranports, it's with the system admins who maintains the DHCP server (scopes).  Is there a way that I can stimulate a DHCP relay on a network to a remote dhcp server using an ip helper address?

I would then enable dhcp debugging to view the transaction.  The debugging is simple, but I need to figure a way to test dhcp relay. Any solution would be appreciated so that I can tell the sysadmin its not the network, but the server.             

[jawad-mukhtar]

Cisco IOS support dhcp relay agent.

You can configure ip helper-address on an interface or vlan.

Please find below Cisco Documentation that might help you.

http://www.cisco.com/en/US/docs/ios/12_4t/ip_addr/configuration/guide/htdhcpre.html

[paul driver]

Yes you can, and then the dhcp packet ( originating from the dhcp client)  will be forwarded as unicast by the relay with a new define   "giaddr ip" which is usually set to the svi interface on where you have applied this relay,

res

Paul

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[davidhuynh5]

Sorry, let me rephrase my question. How do I fake a client on my router or layer 3 switch?

[Giuseppe Larosa]

Hello David,

if you want a different router to act as a DHCP client you can use

ip address dhcp

in interface config mode

But it has to be a different router /router interface then the one performing DHCP relay function

Hope to help

Giuseppe

[SOcchiogrosso]

You could look into configuring a IP SLA on the ciao for DHCP this will not solve the problem but it give you a better look at the process from the routers perspective and provide better logging from the network perspective.

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