From: Mark Lewis (markl11@xxxxxxxxxxx)
Date: Mon Feb 04 2002 - 16:10:54 GMT-3
As far as iBGP behaviour not constituting 'split-horizon', Cisco themselves
refer to the previously referenced behaviour as 'BGP Split-Horizon' (see the
BSCN & BSCI courses). However, the RFCs do not, as far as I'm aware, refer
to it as 'split-horizon', so take your pick.
Rgds,
Mark
>From: Peter van Oene <pvo@usermail.com>
>Reply-To: Peter van Oene <pvo@usermail.com>
>To: John Neiberger <neiby@ureach.com>, "Mark Lewis" <markl11@hotmail.com>,
> ccielab@groupstudy.com
>Subject: Re: Re: Junos BGP routes update
>Date: Mon, 04 Feb 2002 12:05:53 -0500
>
>Issue is likely even simpler and the question stems likely from a variance
>in behavior. If A EBGP peers with B, in Juniper, A will send directly back
>the B the paths received from B. B then drops per the AS-Path
>loop. However, Cisco's implementation will automatically prune these
>advertisements in a split horizon like method.
>
>Also, as previously discussed (though maybe on the juniper list?), IBGP
>advertisement rules do not constitute a split horizon implementation.
>
>At 10:57 AM 2/4/2002 -0500, John Neiberger wrote:
>>That statement is certainly true but I thought we were
>>discussing eBGP, not iBGP. I thought he was referring to a
>>scenario where an eBGP peer receives an update from another
>>eBGP peer that includes its own ASN.
>>
>>Let's say AS1 has routers A and B, both of which are connected
>>to AS2, routers C and D. Both A and B advertise their prefices
>>to C and D who in turn trade updates. Then C will advertise
>>back to AS1 the routes it learned from D. The receiving router
>>in AS1 will see its own ASN in the AS-PATH and drop the update.
>>
>>I believe that the original poster thought that AS2 wouldn't
>>even transmit an update to AS1 that had AS1 in the AS-PATH.
>>I'm fairly sure that it is up to the receiving router to check
>>the AS-PATH for its own ASN, not the advertising router.
>>
>>Regards,
>>John
>>
>>
This archive was generated by hypermail 2.1.4 : Thu Jun 20 2002 - 13:46:11 GMT-3