DHCP using HSRP with ip helper-address

[jason....@funb.com]

From a trace, I notice that DHCP 0.0.0.0 Requests sent to a HSRP
interface which are helper forwarded, use the physical address and not
the ip standby address.

My DHCP implementation is static, so it matches the Relay IP address
(giaddr) to a table of MAC addresses and assigns the corresponding ip
address from a table. There is nothing "dynamic" about my DHCP
implementation.

Since the ip helper-addresses uses the Physical giaddr, it breaks my
DHCP.

Is there a workaround to make the ip helper-address use the HSRP ip
standby address ?

Jason Aarons, MCSE, CCNA

[Michael Rausch]

jason....@funb.com wrote:
>
> From a trace, I notice that DHCP 0.0.0.0 Requests sent to a HSRP
> interface which are helper forwarded, use the physical address and not
> the ip standby address.

That's what it is supposed to do! Same as telnetting to the
HSRP address doesn't work.

> My DHCP implementation is static, so it matches the Relay IP address
> (giaddr) to a table of MAC addresses and assigns the corresponding ip
> address from a table. There is nothing "dynamic" about my DHCP

> Is there a workaround to make the ip helper-address use the HSRP ip
> standby address ?

What about duplication all your entries for both relay addressses?
Or waiting until Cisco supports VRRP one day?

Regards,

Michael

--
Michael Rausch
rau...@uni-koblenz.de

[Thomas M. Thomas II]

No that is not possible.

-----Original Message-----
From: jason....@funb.com [mailto:jason....@funb.com]
Sent: Wednesday, September 23, 1998 3:45 PM
To: ci...@spot.colorado.edu
Subject: DHCP using HSRP with ip helper-address

>From a trace, I notice that DHCP 0.0.0.0 Requests sent to a HSRP
interface which are helper forwarded, use the physical address and not
the ip standby address.

My DHCP implementation is static, so it matches the Relay IP address

(giaddr) to a table of MAC addresses and assigns the corresponding ip
address from a table. There is nothing "dynamic" about my DHCP

implementation.

Since the ip helper-addresses uses the Physical giaddr, it breaks my
DHCP.

Is there a workaround to make the ip helper-address use the HSRP ip
standby address ?

Jason Aarons, MCSE, CCNA

[Lee, Paul]

Would using the burned in option of HSRP help here?

'use bia'

Paul Lee
Liberty Mutual Group
603-431-8400 X53279

[Stephen Elias]

I use DHCP with HSRP all the time, no problems.

However, it seems you have a unique configuration "static dhcp".

Who's DHCP Server product are you using ???

[Joseph Java]

I have read somewhere that with DHCP you can actually set up static
pairings of mac and ip addresses, for some or even all of your
dhcp-assigned addressing if you want. It would be just as much work to
manage this as to put static IP's on machines, but perhaps less
time-consuming since you are managing them all in one central
location. We use a Cisco DHCP server product, the exact name escapes
my memory, but it runs on an AIX box.
Where I work we also use DHCP with HSRP. A trace will return the
the active physical address. But how does this tell you that dhcp
requests are also using the physical address? It would only tell you
how traceroute is behaving in that environment. I would use a sniffer
to look at this. If you don't have one, perhaps a logged access-list
or a debug would show you for sure what the dhcp requests were doing.
On our ISL'd subinterfaces (fastethernet) and on our 10Mb ethernet,
all using dhcp and hsrp, we have a statement "no ip redirects". You
could try that one out. I looked and found we don't have a "standby
use-bia" for what its worth. But you could try that too.
-JJ

On Wed, 21 Oct 1998 18:16:24 GMT, steven...@ml.com (Stephen Elias)
wrote: