[j-nsp] load balancing in Route reflector scenario

[Keegan Holley]

I think the advertise inactive knob turns that off, but I don't know for
sure because I've never tried it.  I know it's not supported on cisco
routers.  The reason for it is the size of the BGP table.  So if the table
is 400k routes and you have 5 different ISP's and you advertise every route
that would be 2M routes in the table.  Since BGP doesn't allow multiple
version of the same route in the routing table (separate from the BGP table
where incoming routes are stored) you would still only use the original 400K
the other 1.8M routes would just go unused unless you manipulated them some
how.

2011/8/10 Ivan Ivanov <ivanov.ivan at gmail.com>

> Hello,
>
> On this link http://goo.gl/6FgnZ from Cisco site you can find the
> below quote:
>
> "Route Reflector Limitation
>
> When multiple iBGP paths installed in a routing table, a route reflector
> will advertise only one paths (next hop). If a router is behind a route
> reflector, all routers that are connected to multihomed sites will not be
> advertised unless a different route distinguisher is configured for each
> VRF."
>
> To be honest I don't why is like this, but I think that with 'multipath' it
> won't work.
>
> HTH
>
> On Wed, Aug 10, 2011 at 23:32, Humair Ali <humair.s.ali at gmail.com> wrote:
>
> > just to clarify ,
> >
> > you have :
> >
> > PE2 with 2 link , 1 to RR1 (let's call it link 1)  and 1 to RR2 (link 2)
> > PE3 with 2 link , 1 to RR1 (let's call it Link 3) and 1 to RR2  (link4)
> >
> > you could set local pref to link to PE2 to 150 (RR1 to PE2 will be
> > preferred), and link 2 (PE2 to RR2) as standard 100
> > then set link 3 standard 100 (PE3 to RR1)  but set link 4 with 150  (RR2
> to
> > PE3 will be preferred)
> >
> > then RR1 has prefered path via PE2 (via link 1 high local pref), RR2 have
> > prefered path via PE3( via link 4 high local pref) , Each RR may
> advertise
> > both route to PE1
> >
> > then on PE1 , u need load balancing configured , I can't guarantee either
> ,
> > but need to be tested.
> >
> > On 10 August 2011 21:06, Stefan Fouant <sfouant at shortestpathfirst.net
> > >wrote:
> >
> > > Have you tried the advertise-inactive knob on the RR? I can't guarantee
> > > that this will work but it just might also advertise the route towards
> > PE3
> > > as well.
> > >
> > > Of course, if this works, then you would need to enable multipathing on
> > PE1
> > > accordingly.
> > >
> > > Stefan Fouant
> > > JNCIE-M, JNCIE-ER, JNCIE-SEC, JNCI
> > > Technical Trainer, Juniper Networks
> > > http://www.shortestpathfirst.net
> > > http://www.twitter.com/sfouant
> > >
> > > Sent from my iPad
> > >
> > > On Aug 10, 2011, at 2:44 PM, biwa net <biwa2go at gmail.com> wrote:
> > >
> > > > Dear All
> > > >
> > > > I have a setup where I need to load balancing routes received from 2
> RR
> > > in
> > > > IPV4 environment (not VPN-IPV4)
> > > >
> > > > I have my  PE (let's called PE1) connected to 2 RR (cluster), my
> > > destination
> > > > subnet eg: 10.1.1.1/24 is behind 2 PE (PE-2 and PE3) which are also
> > > client
> > > > of the same 2RR
> > > >
> > > > PE-2 and PE3 are sending the same route 10.1.1.1/24 to the RR ,
>  which
> > > as
> > > > per normal behavior is selecting the best route to PE1  ,
> > > >
> > > > My issue is that RR is always advertising the route
> 10.1.1.1/24through
> > > PE2
> > > > (due to lower router id) as best path and I would like to load
> balanced
> > > it
> > > > through PE2 and PE3
> > > >
> > > > Anyone can recommend a way to load balance ?
> > > >
> > > > Unfortunately I dont have a lab to test any solution and there are
> live
> > > > traffic on this ,so all I can do is guessing is whether the below 2
> > > option
> > > > would work or not.
> > > >
> > > > 2 option I have
> > > >
> > > > 1.So here I am trying to thinking about testing the multipath command
> > > under
> > > > the RR configuration  to see if I am receiving routes from both PE or
> > not
> > > ,
> > > >
> > > > 2.  try to put all devices them in routing instance VRF , with the
> BGP
> > > > configuration under it (both RR and client) , and RD configured in
> the
> > > VRF
> > > > (but not putting any vpn family under bgp) so that it stays IPV4
> routes
> > ,
> > > > maybe I could cheat the RR to believe these are 2 differentes routes
> > due
> > > to
> > > > the RD, but dont know if this works or not .
> > > >
> > > > anyone has had similar issue and found a workaround ?
> > > >
> > > > does the 2 option above actually work or not ?
> > > >
> > > > thanks for any input
> > > > _______________________________________________
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> >
> >
> >
> > --
> > Humair
> > _______________________________________________
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> >
>
>
>
> --
> Best Regards!
>
> Ivan Ivanov
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