BGP Max-paths doesn't work

[John Blakley]

I have a lab set up testing out multipath bgp, but it just isn't working. Here's what I have:

R3#sh ip bgp vpnv4 vrf CustA

BGP table version is 23, local router ID is 3.3.3.3

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

              r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path

Route Distinguisher: 14:14 (default for vrf CustA)

*  0.0.0.0          172.35.0.5               0             0 5 i

*>                  172.34.0.4               0             0 4 i

*>i1.1.1.1/32       2.2.2.2                  0    100      0 1 i

*  33.33.33.33/32   172.35.0.5               0             0 5 i

*>                  172.34.0.4               0             0 4 i

R3# sh ip route vrf CustA

     33.0.0.0/32 is subnetted, 1 subnets

B       33.33.33.33 [20/0] via 172.34.0.4, 00:07:23

R3# sh run | s router bgp

address-family ipv4 vrf CustA

  neighbor 172.34.0.4 remote-as 4

  neighbor 172.34.0.4 activate

  neighbor 172.35.0.5 remote-as 5

  neighbor 172.35.0.5 activate

  maximum-paths 4

  no synchronization

  network 172.34.0.0 mask 255.255.255.0

No matter what I do it doesn't put the second route in the table. Any ideas?

[Thotsaphon Lueangwattanaphong · Accepted solution]

Hello,

   Are you trying to install 2 identical EBGP routes from 2 ISPs? You're going to need a hidden command for this. You might try the following command in the lab.

!

bgp bestpath as-path multipath-relax

!

  It's a good idea to execute "clear ip bgp *"

   I personally like NIL for BGP stuffs.

Ref: http://wiki.nil.com/Multipath_Load_Sharing_with_two_ISPs

HTH,

Toshi

[Stephane Bonnet]

Excellent thx for the share great command to know

Stephane

[John Blakley]

I guess from a theoretical standpoint this would be the case. I'm actually doing 2 separate locations to a single ISP, but if you reverse that I could see it being this way. So my next question would be is this something that the ISP would support by default or would I need to work something out with them? I'm trying to get two default routes into the ISP's routing table to try to load balance toward my locations, but not the other way around.

[John Blakley]

That fixed my issue, but I'm not sure if the ISP has that set by default or if they'd even want to. My other concern is the fact that I'm not 100% certain if I can selectively state 'I want this path in the routing table, but not this one multiple times'. This is allowing any multiple paths that I have which could pose a problem.

[cadet alain]

Hi,

as it only impacts the installation of both BGP learned routes in your RIB it has nothing to do with the ISP,that's how I see it anyway.

as it only relaxes the AS_PATH requirement you surely may alter other attribute to make a path not installed multiple times.

Regards.

Alain

[John Blakley]

Alain,

That's true if I were doing this from the perspective of my router and 2 separate ISPs, but I'm needing to do the reverse. I have 2 datacenters that have an mpls connection with our provider. We have 2 different ASs that peer with the ISP and I want to send a default route from both of my ASs to the ISP for them to put in their RIB. I was wanting the ISP to load balance the default traffic from my other locations through both of my datacenters instead of just my main site.

Thanks,

John

[cadet alain · Accepted solution]

Hi John,

ok I understand so now you'll have to ask your ISP if they support this feature and are willing to implement it  for you.

Regards.

Alain

[John Blakley]

Yeah..that's what I was afraid of Thanks!