RE: [j-nsp] BGP route

From: Julian Eccli (je@juniper.net)
Date: Mon Feb 04 2002 - 04:05:37 EST


Answers inline...

> -----Original Message-----
> From: andrew kevin [mailto:andrewkevin2000@yahoo.com]
> Sent: Sunday, February 03, 2002 8:13 PM
> To: juniper-nsp@puck.nether.net
> Cc: juniper@groupstudy.com
> Subject: [j-nsp] BGP route
>
>
> Hi,
> I found it's strange that BGP of Junos can't follow
> the split-horizon rule(BGP is a DV routing protocol),

split-horizon is not used in BGP and BGP is considered a path vector
protocol.

> after receiving EBGP neighbors route , it will send
> back those route which learns from the original one to
> the source, and the original will reject these routes
> according to the AS-PATH attribute.
> It will waste the router's resource to send those
> routes.
> It is different with Cisco's implementation.
> Cisco will not send back to the original.It seems even
> reasonable.

RFC1771 states it's optional to advertise or not advertise back from the
neighbor the route is received from in section 9.1.3. In a modern day
environment it would not matter, and should have no impact on router or
link performance since we only send back what is sent to us.

> Or must we configure a policy to preven Junos from
> sending updates back?
> Or any better method?

You need to set up an export policy on the peer to prevent readvertising
back to your neighbor.

-Julian



This archive was generated by hypermail 2b29 : Mon Aug 05 2002 - 10:42:39 EDT