[j-nsp] BGP and OSPF ECMP
Marlon Duksa
mduksa at gmail.com
Fri Jul 18 14:43:14 EDT 2008
I'm sending traffic to 50K IP destinations. All this is in VPN (2547). So I
should have 50K flows if destination IP is taken into account during
hashing. Please keep in mind that this IP is encapsulated in two MPLS
headers as the traffic is going through MPLS tunnel (LDP based) and then the
second label is the vrf label. The next hop (PE) router is advertised
through OSPF.
Thanks,
Marlon
On Thu, Jul 17, 2008 at 5:24 PM, Harry Reynolds <harry at juniper.net> wrote:
> Hmm. Normally for LB we expect to see a ulst next hop, which in turn
> contains two or more ucst NHs. The FT display indicates that a single NH is
> installed for that prefix.
>
> Can you describe the nature of the test traffic? If its all one flow I'd
> expect all to take the same NH even when LB is in effect. AFAIK, MX behavior
> is no different here.
>
>
>
> Regards
>
>
>
>
>
>
> > -----Original Message-----
> > From: Marlon Duksa [mailto:mduksa at gmail.com]
> > Sent: Thursday, July 17, 2008 1:57 PM
> > To: Harry Reynolds; juniper-nsp at puck.nether.net
> > Subject: Re: [j-nsp] BGP and OSPF ECMP
> >
> > I tried this on MX960 and it seams that load balancing is on
> > by default. How do I turn load balancing off?
> > In the RT I can see both next hops:
> > 2.2.2.2/32 *[OSPF/10] 02:21:29, metric 1
> > to 10.0.2.2 via ge-8/0/5.0
> > > to 10.0.3.2 via ge-5/1/0.0
> >
> >
> > In the FT I can see only one path:
> > 2.2.2.2/32 user 1 10.0.3.2 ucst 572
> > 5 ge-5/1/0.0
> >
> > But when I actually send traffic and run 'monitor interface
> > traffic', I see that traffic is going out over both links.
> > This 2.2.2.2 next hop is actually a PE router in VPN.
> >
> > Is load balancing on by default on MX? I didn't configure
> > anything special to turn it on.
> >
> >
> > On Tue, Jul 15, 2008 at 6:43 AM, Boyd, Benjamin R
> > <Benjamin.R.Boyd at windstream.com> wrote:
> >
> >
> > You can further control the flow with:
> >
> > [edit forwarding-options hash-key]
> >
> > family inet {
> > layer-3;
> > layer-4;
> > }
> > family mpls {
> > label-1;
> > label-2;
> > }
> >
> > If you're load balancing over a decent amount of hops I
> > wouldn't hash
> > both layer-3/layer-4 and label-1/label-2 on every
> > router because then
> > your per-flow becomes quite segregated and you might
> > find issues where
> > your load balancing on many routers will break the
> > seemingly load
> > balancing of another router since the hashing algorithm
> > will produce the
> > same result on each router.
> >
> > -Ben
> >
> >
> > -----Original Message-----
> > From: juniper-nsp-bounces at puck.nether.net
> >
> > [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf
> > Of Harry Reynolds
> > Sent: Monday, July 14, 2008 6:18 PM
> > To: Marlon Duksa; juniper-nsp at puck.nether.net
> > Subject: Re: [j-nsp] BGP and OSPF ECMP
> >
> > Do you have a per-packet (really per flow) LB policy
> > applied to the
> > forwarding table?
> >
> > This is needed to install two or more forwarding paths
> > in the pfe. BGP
> > multipath is a control plane tie breaker, but by
> > default only one of the
> > winners is installed as active in the FT.
> >
> > HTHs
> >
> >
> > [edit]
> > regress at asahi# show policy-options
> > policy-statement lb {
> > then {
> > load-balance per-packet;
> > }
> > }
> >
> > [edit]
> > regress at asahi# show routing-options forwarding-table
> > traceoptions {
> > file forwarding_table;
> > flag route detail;
> > }
> > export lb;
> >
> >
> > > -----Original Message-----
> > > From: juniper-nsp-bounces at puck.nether.net
> > > [mailto:juniper-nsp-bounces at puck.nether.net] On
> > Behalf Of Marlon Duksa
> > > Sent: Monday, July 14, 2008 3:22 PM
> > > To: juniper-nsp at puck.nether.net
> > > Subject: [j-nsp] BGP and OSPF ECMP
> > >
> > > Does anyone know how to enable ecmp in Junos (I'm on M320
> > > with Junos 9.0)?
> > >
> > > I have a vrf with BGP configured for multipath. In the
> > > forwarding table I see only one path installed even though I
> > > have two equal cost physical links to the NH.
> > > My IGP is OSPF and in the routing table OSPF is showing two
> > > paths (only one active >) and in the fwd table only one path
> > > is selected. How do I force Junos to select both links.
> > >
> > > Similar with LDP which is used for the transport (tunnel) in
> > > this VPN environment.
> > >
> > > So it looks to me that multipath in BGP is not taking effect
> > > because underlying protocols (OSPF and LDP) is not utilizing
> > > both links??
> > > Thanks,
> > > Marlon
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