[j-nsp] BGP load-balancing
harry at juniper.net
Wed Mar 25 18:08:37 EDT 2009
Coming in late, but I feel the types of question you ask indicate your
preparing well. ;)
That said, I think a FT LB policy is best here, and consider the
omission a piece of errata. If we were not advertising a single rip
summary than perhaps the default per-prefix would apply. As documented
we have two control plane next hops, but a single data plane one. It
would be best to have two at both levels.
From: juniper-nsp-bounces at puck.nether.net
[mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Aamir Saleem
Sent: Wednesday, March 25, 2009 1:02 AM
To: Patrik Olsson; Juniper Puck
Subject: Re: [j-nsp] BGP load-balancing
thanks for your inputs.
On Wed, Mar 25, 2009 at 1:58 AM, Patrik Olsson <df at webkom.se> wrote:
> bgp multipath only enables per prefix loadbalancing.
> To achieve per flow loadbalance aswell you need to apply a per packet
> loadbalance policy under routing-options forwarding-table.
> Aamir Saleem wrote:
> > Hi All,
> > I need your input regarding BGP loadbalancing with multipath option.
> > In JNCIP-M study guide, one of the requirement given in iBGP case
> > study
> > to "Redistribute a summary of the RIP routes into IBGP from both r6
> > and
> > and in second requiement "r5 must IBGP load-balance to the summary
> > route representing the RIP prefixes".
> > After advetiseing RIP summary route (192.168.0.0/22) from R6 and R7.
> > R5 router is able to see two viable next-hops after enabling
> > multipath in R5 ibgp group but in forwarding table of R5 shows only
> > one path via R6 is available.
> > My question is:
> > Is only enabling multipath option will achive above mention
> > requirement regarding BGP loadbalancing ?
> > As junos perform per-prefix loadbalncing by default so the iBGP case
> > requiremnt that "r5 must IBGP load-balance to the summary route
> > the RIP prefixes" cannot be achiedved by with multipath only. All
> > other router behind R5 router also following the same path as chosen
> > some output from test senario are below:
> > aamir at LAB1 <aamir at LAB1># run show route protocol bgp logical-router
> > R5
> > 192.168.0.0/22
> > inet.0: 80 destinations, 136 routes (80 active, 0 holddown, 0
> > hidden)
> > + = Active Route, - = Last Active, * = Both
> > 192.168.0.0/22 *[BGP/170] 01:50:49, localpref 100, from 10.0.9.6
> > AS path: I
> > > to 10.0.8.6 via lt-1/2/0.116
> > to 10.0.8.10 via lt-1/2/0.117
> > [BGP/170] 01:50:49, localpref 100, from 10.0.9.7
> > AS path: I
> > > to 10.0.8.10 via lt-1/2/0.117 
> > aamir at LAB1#
> > Forwarding table:
> > Logical router: R5
> > Routing table: inet
> > Internet:
> > Destination Type RtRef Next hop Type Index NhRef
> > 192.168.0.0/22 user 0 indr 262148
> > 10.0.8.6 ucst
> > 7 lt-1/2/0.116
> > Any input is more then welcome.
> > Regards.
> > Aamir
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