Re: Split-horizon enable/disable

From: Petr Lapukhov (petrsoft@gmail.com)
Date: Thu May 11 2006 - 10:53:23 ART


The main things to remember with split horizon:

1) You should remember that physical FR interface has "ip split-horizon"
    enabled by default. Pay attention to this with RIP configurations.

2) EIGRP has different command for split horizon; it is on by default
    on every interface

3) You need to disable split-horizon if you want to advertise secondary IP
    back the same interface.

4) A way to work out H&S problem w/ split-horizon is update unicasting.

5) Split-horizon applies to redistributed routes. That is, if if you receive
routes
    via one interface and try send them back the same interface,
redistibuting into
    another protocol, you need to disable split horizon. Protocols need to
be
    distance-vector, of course :)

6) Split-horizon is turned on for RIPng on every inteface by default. You
can disable it
    only per-process.

There are more things, but they are not that important :)

HTH
Petr

2006/5/11, Schulz, Dave <DSchulz@dpsciences.com>:
>
> Sami -
>
> Take a look at the docCD on what split-horizon does, by disallowing
> advertising what it receives on an interface to be sent out the same
> interface. So if you are on hub and spoke, for example, and need to get
> the inform from a spoke to another spoke (received at the hub, set up as
> multipoint)....you will need to disable it. HTH.
>
>
> Dave Schulz,
> Email: dschulz@dpsciences.com
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Sami Salim
> Sent: Thursday, May 11, 2006 6:56 AM
> To: CCIE Group Syudy
> Subject: Split-horizon enable/disable
>
> Hi folks,
> I am trying to understand the logic to enable/disable split-horizon on
> distance-vector interfaces; like ethernet sub-interface, physical serial
> f/r, sub-interface serial f/r and lastly the hub&spoke physical and
> sub-interface.
>
> Thank you
>
>
>
> ---------------------------------
> Now you can have a huge leap forward in email: get the new Yahoo! Mail.
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html



This archive was generated by hypermail 2.1.4 : Thu Jun 01 2006 - 06:33:21 ART