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DHCP relay + IP unnumbered problems

Three problems with DHCP relay + IP unnumbered in a DSL deployment

on 12.2(7c). I'm pretty sure they are bugs that others have run into, but there's nothing in the bug toolkit. Before talking to TAC, I wanted to see if anyone can confirm this behavior.

PROBLEM 1. IOS 12.2 documents the 'clear ip route dhcp' command, yet this command is not available on 7200s. It seems to be available in 12.2T only. Anyone know what gives?

PROBLEM 2. The monitoring of lease validity between client and server seems flawed. E.g., if a client releases, the static host route is not removed. Worse yet, when a client renews, the renewal is not recognized by the router. Say the lease time is 4 hours...

- 12pm Client requests and gets a DHCP lease, router installs a static route with an expiration time of 4pm.

- 2pm Windows client renews lease because lease is half-way done. DHCP server approves another 4 hour lease. Router seems to ignores the renew.

- 4pm [a] Router notes the expired lease and removes the static route and [b] Windows client renews lease because lease is half-way done.

If [a] happens before [b], everything is "fine" because [b] will cause the router to reinstall the route. I say "fine" because DHCP renewal times are hardly precise and the client does lose connectivity for anywhere from 1 to 10 seconds.

But if [b] happens before [a], then the client will be without a route until they manually release/renew, sit idle for 2 hours, or reboot.

PROBLEM 3. A device requests DHCP and a static route is built. The same device moves to a different PVC/subinterface and requests again. The DHCP relay does not remove the first static route. One must wait the DHCP lease time for the router to remove the route before the device can begin to work.



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Re: DHCP relay + IP unnumbered problems

I run 12.2(10b) and I see the command available. May be you want to check it once again.

I too checked the toolkit for any possible known bugs. I got about 50 results under DHCP in the release that you specified, but was not able to decide which one is yours. May be you want to go through them again.

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