From: Alan Kucharski (akuchars@xxxxxxxxx)
Date: Mon Aug 05 2002 - 16:40:02 GMT-3
Dennis,
Propagate NEXT_HOP unchanged to eBGP
Ability to advertise BGP prefixes to an eBGP peer without modifying
the next-hop value
Used in VPN and non-VPN MPLS networks to set up end-to end LSPs
Ability to set NEXT_HOP on a RR
Ability to set the next-hop to self on a RR when reflecting a path.
The neighbor x.x.x.x next-hop-self command will only effect routes from
eBGP peers (i.e. non-reflected routes)
The next-hop can only be modified for a reflected route via an
outbound route-map
set ip next-hop 1.1.1.1
Why would you want to modify the next-hop of a reflected route?
If RR (the route-reflector) is using iBGP multipath then traffic
from R4 needs to come through RR for load-balancing purposes
If RR does not set the next-hop to self, all traffic from R4 will
go straight to R2
R4---------RR---------R2
| |
|_______R3
RR#
router bgp 100
neighbor 4.4.4.4 route-reflector-client
neighbor 4.4.4.4 route-map foo out
!
route-map foo permit 10
set ip next-hop 1.1.1.1
Codes that support the next hop modification for an EBGP neighbor: This
is id CSCdt84706 and is integrated in 12.1(9), 12.1(9)E, 12.1(9)EC
-Alan.
At 04:26 PM 8/5/2002 -0700, Dennis Laganiere wrote:
>In a semi-random CCO search I came across "BGP Next Hop Propagation", but
>reading over the few links I've found isn't enough for me to figure it out.
>I've looked through several BGP books and found nothing. I also tried an
>archive search without results. Anybody seen this before? (I've got to
find
>a new hobby... :-)
>
>--- Dennis
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