[j-nsp] BGP load-balancing

[Aamir Saleem]

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 is
to "Redistribute a summary of the RIP routes into IBGP from both r6 and r7"
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 study
requiremnt that "r5 must IBGP load-balance to the summary route representing
the RIP prefixes" cannot be achiedved by with multipath only. All other
router behind R5 router also following the same path as chosen by R5.

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
[edit]
aamir at LAB1#

Forwarding table:
Logical router: R5
Routing table: inet
Internet:
Destination        Type RtRef Next hop           Type Index NhRef Netif
192.168.0.0/22     user     0                          indr  262148     3
                                         10.0.8.6             ucst  974
7 lt-1/2/0.116


Any input is more then welcome.

Regards.
Aamir