RE: Frame Relay and Split Horizon rule of thumb for routing

Hi Hammer,

In the lab the right answer is always going to be a judgment call, based on
a close reading of the task requirements, goals and restrictions and
interactions with other protocols and features. But here are some basics to
consider:

1. Fundamentally, you need only concern yourself with distance vector
protocols: RIP and EIGRP.
2. If the spokes must exchange routes directly, then you will need to
unicast updates using neighbor statements, or you will need to create a
tunnel. No need to disable split horizon on the hub in this case. In fact,
the hub would not have to run the protocol at all.
3. If unicast or tunnels are ruled out, then having the hub relay the routes
is the likely answer. For this you would need to disable split horizon on
the hub interface that is configured with the IP.

For RIP: no ip split-horizon
for EIGRP AS 10: no ip split-horizon eigrp 10

HTH,

Bob Sinclair CCIE 10427 CCSI 30427
CIERS2 Online Instuctor
www.tinyurl.com/ciers2online

> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> --Hammer--
> Sent: Tuesday, October 19, 2010 11:14 AM
> To: 'Cisco certification'
> Subject: Frame Relay and Split Horizon rule of thumb for routing
> protocols
>
> Struggling here. Is there a rule of thumb for this? Given the below
> topology
> where R2 is the hub
>
>
>
> R3 (spoke) -----R2 (hub) ----- R4 (spoke)
>
>
>
> Is there a rule of thumb for when I should consider disabling split
> horizon?
> Like, if it's distance vector you disable split, if it's link state you
> don't. Or is it unique to each routing protocol and how it's applied?
> So
> you'll have to make a judgement call based on the lab scenario.
>
>
>
>
>
> --Hammer
>
>
>
> "I was a normal American nerd."
> -Jack Herer
>
>
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Received on Tue Oct 19 2010 - 11:30:55 ART