The MPLS-OPS Archive

[jim guichard <jguichar@cisco.com>]

its in 12.2T - check :

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122t/122t2/ftbgpls.htm

Jim

At 17:07 16/08/2001 +0100, Pegg Damon wrote:
>The problem (I presume Cisco equipment) is that Cisco don't have a concept
>of iBGP load-balancing unless this has been introduced in 12.2 code.  Within
>iBGP, traffic can be balanced to the bgp-next-hop address based on
>equal-cost IGP metrics but this is IGP balancing and not iBGP.  There is no
>way to choose multiple BGP paths within iBGP from the same device and
>experience has led me to bastardise natural routing with awkward route-maps
>to achieve balancing in symetrical environments.  All other things being
>equal, iBGP decision making is based on router-id, as you surmise.
>
>With a single route-reflector, I suggest segregating routes received and
>advertised using MEDs so that you achieve redundancy and prefix based
>balancing.  In the event of a single prefix you may have to break it down to
>mutliple longer prefixes, carried only internally, as well as potentially
>advertising the customer's supernet externally.
>
>A typical example for a multiple route-reflector environment...
>
>
>---------P (RR)---------PE (RR Client)--------------CE
>            |
>            |
>---------P2(RR)---------PE2(RR Client)--------------CE2
>
>...involves weight-based preference of routes received by the P from the PE
>routers based on as_path regex prefix-list for those routes - i.e. P prefers
>PE for routes from CE and P2 prefers PE2 for routes from CE2.  Of course P
>will also connect physically to PE2; and P2 to PE; but this is not
>represented above because these links won't be used by traffic for this
>specific customer.  That takes care of outbound traffic and the customer can
>take care of inbound by one of these methods (although I have had awkward
>customers have me do use MEDs to handle the inbound traffic too.)
>
>There really isn't a simple solution but believe me I have asked Cisco for
>iBGP multipath support on several occasions :)
>
> > -----Original Message-----
> > From: Robertson, Kevin [mailto:Kevin.Robertson@Quantitude.com]
> > Sent: 16 August 2001 14:50
> > To: 'mpls-ops@mplsrc.com'
> > Subject: Max-Paths & Max-Paths ibgp (MPLS BGP operation)
> >
> >
> > I am looking for help to see how the Max-Paths/Max-Paths Ibgp
> > works within
> > MPLS. I have a multi-homed enviroment and need to
> > load-balance to my final
> > destination down 2 alternate links.
> >
> > Help Needed.......
> >       I am running IBGP and EBGP in my environment, IBGP
> > between the Core
> > multi-homed locations and EBGP down to the Destination host
> > CE's. I would
> > like to know how the Max-Paths/Max-Paths IBGP affects the
> > other multi-homed
> > routers in my environment without the need for
> > Load-Balancing.... (I sort of
> > know how to get around that with route maps but unsure in the
> > MPLS world),
> > However I am unable to get the Load-Balancing working and can
> > only get the
> > traffic to go via best path determined by BGP. (Usually the
> > Highest Router
> > ID)
> >
> > Please note I have set the Med's down at the CE level for
> > equal cost paths,
> > also running AS override and Route maps Set00 up at the PE routers.
> >
> > Any test configurations would be a bonus.
> >
> >
> >               PE-------EBGP-------CE\
> >               |                              |   \
> > R Reflec-----------   IBGP               IBGP >destination host
> >               |                          |   /
> >               PE-------EBGP-------CE/
> >
> >
> >
> > Regards,
> >
> > Kevin Robertson
> >
> > Senior Network Engineer
> > Network Planning & Engineering
> > Quantitude Inc
> > 5350 S. Valentia Way
> > Englewood, CO 80111,USA
> > Tel:  +001 720-535-2232
> > Efax: +001 503 907 8435
> > Email:   Kevin.Robertson@quantitude.com
> >
> >
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Jim Guichard CCIE #2069
Technical Leader EMEA
MPLS & IP Routing Technologies

+44 208 756 8806
Mobile: +44 7802 809763

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