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davidhuynh5
Beginner

Testing DHCP Relay

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.             

5 REPLIES 5
jawad-mukhtar
Enthusiast

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

Jawad
paul driver
VIP Expert

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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Kind Regards
Paul

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

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
Enthusiast

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.

Sent from Cisco Technical Support iPad App

-- CCNP, CCIP, CCDP, CCNA: Security/Wireless Blog: http://ccie-or-null.net/