Re: RIP Timers

1. I think that there is a bug in the debug. Max metric in RIP is still 16.

2. I can see that updates are received and sent with metric 16. I did a test
with this topology:
R1--R2--R3--R4--R5
R1 advertises 192.168.1.0/24
When I remove 192.168.1.0/24 <http://1.1.1.0/24>on R1 (shut down int L0) i
see following messages (#debug ip rip) on all routers:

*Mar 1 00:04:43: RIP: received v2 update from 10.1.23.3 on FastEthernet0/1
*Mar 1 00:04:43: 192.168.1.0/24 via 0.0.0.0 in 16 hops (inaccessible)

*Mar 1 00:04:50: RIP: build update entries
*Mar 1 00:04:50: 192.168.1.0/24 via 0.0.0.0, metric 16, tag 0

3. As for seeing hold timer in action I am in the same boat as you. If I
understand correctly, hold timer should prevent the route to be accepted
again via an alternate route until Hold Timer is reached. But when I bring
up the failed route ON ANOTHER ROUTER before the theoretical Hold Timer is
reached, all routers will reinstall route 192.168.1.0 immediately.

Me to I would like to see a simple topology to prove how Hold Timer works.

On Thu, Mar 31, 2011 at 3:04 AM, Daniel Dib <daniel.dib_at_reaper.nu> wrote:

> Hi,
>
> I'm trying to fully understand the timers used in RIP.
>
> Update timer: Send updates every 30 seconds
> Invalid timer: After 180 seconds invalidate routes but keep them in routing
> table
> Hold down timer: 240 seconds, should be used when we receive route with
> higher metric than in routing table?
> Flush timer: After 240 seconds delete route from routing table
>
> I did a very basic lab with three routers and debugging enabled (ip
> routing,
> rip database and rip events) and tried to look at the output.
>
> *Mar 1 00:13:46.595: RIP-DB: invalidated route of 1.1.1.1/32 via
> 192.168.0.2
> *Mar 1 00:13:46.595: RIP-DB: Remove 1.1.1.1/32, (metric 4294967295) via
> 192.168.0.2, FastEthernet0/0
>
> This is after roughly 180 seconds, this must be the invalid timer in
> action.
> Is there a reason why the metric is so high, it seems to be 2^32. Also I'm
> not seeing that the updates sent out are sent with a metric of 16,
> shouldn't
> that be the case?
>
> I'm not sure how to see the hold down timer in action, is there a good test
> to run?
>
> After 240 seconds the garbage collector flushes the routes:
>
> *Mar 1 00:14:46.603: RIP-DB: garbage collect 1.0.0.0/8
> *Mar 1 00:14:46.603: RIP-DB: garbage collect 1.1.1.1/32
>
> Can anyone please shed some light on these timers. Thanks.
>
> Daniel
> http://www.lostintransit.se
>
>
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Received on Thu Mar 31 2011 - 13:33:15 ART