[j-nsp] MPLS LSP Load Balance

[Jonathan Woolley]

Hi Telmo,
Your initial assumtion is correct, the lower end M series can't hash based
on two MPLS label and IP payload, if you configure that it will hash based
on the top label and the IP payload. I believe this is due to a hardware
limitation as a T320 running the exact same code can hash based on all three
(I've seen this in our lab). In practice this should not affect your load
balancing unless you have a very large traffic stream to one LSP endpoint
without any variation in source or destination IP address (or a variation
such that the hash always chooses the same link). This is highly unlikely
for internet traffic but if you have a SAN or something you could very well
run into the problem. This is the configuration we have:

forwarding-options {
    hash-key {
        family mpls {
            label-1;
            label-2;
           payload {
                ip;
           }
       }
    }
}
routing-options {
    forwarding-table {
        export rp-core-load-balance;
    }
}
policy-statement rp-core-load-balance {
    term core {
        from instance master;
        then {
            load-balance per-packet;
        }
    }
}

If you are testing in the lab then make sure you traffic generator sends
multiple IP streams with a constant source address and the destination
address incrementing by one for each stream. You should then see load
balancing.

Jonathan

On Fri, Feb 4, 2011 at 6:34 AM, Thedin Guruge <thedin at gmail.com> wrote:

> Hi,
>
> If LDP is used for MPLS signaling, and your igp has two equal cost paths
> (via two diff interfaces) to the destination you want load balancing, then
> i
> don't see why it shouldn't occur. ECMP is on by default in Junos and yeah
> M's can only hash on first mpls label and ip payload, but it shouldn't
> matter for your case, i've seen M10s hashing LDP traffic for IGP equal cost
> destinations. btw, what's your IGP?
>
> Cheers
>
> Thedin
>
> On Fri, Feb 4, 2011 at 5:13 AM, Matthew Tighe <matthew.e.tighe at gmail.com
> >wrote:
>
> > I think you may to do this for LDP LSPs. My experience is with RSVP LSPs
> > but
> > the concept should be the same. Multiple LSPs are needed to load balance.
> > Seems like this command does that with LDP:
> >
> >
> >
> http://www.juniper.net/techpubs/en_US/junos10.4/topics/usage-guidelines/mpls-configuring-fec-deaggregation.html
> >
> > <
> >
> http://www.juniper.net/techpubs/en_US/junos10.4/topics/usage-guidelines/mpls-configuring-fec-deaggregation.html
> > >
> >
> > On Thu, Feb 3, 2011 at 7:54 AM, Ezequiel Carson <ezequiel at ifxcorp.com
> > >wrote:
> >
> > > Matthew,
> > >
> > > Our lsp's arw dinamicaly built using ldp.
> > >
> > > this issue is happening when you the router receives an incomming mpls
> > > packet (labeled).
> > >
> > > Resuming: once the router has placed the label 112233 on interfaces X,Y
> > and
> > > Z , every single packet will be routed using the same interface ex: X
> and
> > > never will use Y or Z
> > >
> > > We already have configured the forwarding-option hash algorith but is
> not
> > > working
> > >
> > > Txs
> > > Ezequiel
> > >
> > > ------------------------------
> > >  *From*: Matthew Tighe <matthew.e.tighe at gmail.com>
> > > *To*: Telmo Di Leva
> > > *Cc*: juniper-nsp at puck.nether.net <juniper-nsp at puck.nether.net>;
> > Ezequiel
> > > Carson; Andres Arturo Diaz Montes
> > > *Sent*: Thu Feb 03 10:47:27 2011
> > > *Subject*: Re: [j-nsp] MPLS LSP Load Balance
> > >
> > > Do you have multiple LSPs defined (one for each path you want to load
> > > balance over)?
> > >
> > > On Tue, Feb 1, 2011 at 6:46 PM, Telmo Di Leva <tdileva at ifxcorp.com>
> > wrote:
> > >
> > >> Dear JNSP, in this oportunity we are contacting you because we have
> the
> > >> following trouble:
> > >> Our core plataform is based on M20 and M160.
> > >> For some reason, we cant balance mpls traffic thru multiples oc3.
> > >> We have this links explaining our limitation whit M series:
> > >>
> > >>
> >
> http://www.juniper.net/techpubs/en_US/junos9.5/information-products/topic-collections/config-guide-mpls-applications/mpls-configuring-load-balancing-for-mpls-lsps.html
> > >> Note: You can include this combination of statements on M320 and
> > T-series
> > >> routing platforms only. If you include them on an M-series router,
> only
> > the
> > >> first MPLS label and the IP payload are used in the hash key.
> > >> Can this would be a problem to balance traffic in our backbone?
> > >> We cant find a way to fix the unbalanced mpls traffic.
> > >> Is corrected in some JUNOS version for M series?
> > >> We will really apreciate your help.
> > >> Bes regards.
> > >>
> > >>
> > >>
> > >> _______________________________________________
> > >> juniper-nsp mailing list juniper-nsp at puck.nether.net
> > >> https://puck.nether.net/mailman/listinfo/juniper-nsp
> > >>
> > >
> > >
> > >
> > > --
> > > Matthew Tighe
> > > matthew.e.tighe at gmail.com
> > >
> > >
> >
> >
> > --
> > Matthew Tighe
> > matthew.e.tighe at gmail.com
> > _______________________________________________
> > juniper-nsp mailing list juniper-nsp at puck.nether.net
> > https://puck.nether.net/mailman/listinfo/juniper-nsp
> >
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