[j-nsp] BGP EVPN, VXLAN and ECMP

[Nitzan Tzelniker]

Hi,

Just check with 5110 and 5100 and on both I see two next hops
but I am using OSPF for the underlay
I think that you have multipath under BGP from the fact that we see two
paths under inet.0 but do you have forwarding-table policy with
"load-balance per-packet" ?

BTW take a look here
https://www.juniper.net/documentation/en_US/release-independent/solutions/information-products/pathway-pages/lb-evpn-vxlan-tn.pdf


Thanks

Nitzan


On Wed, Mar 28, 2018 at 5:27 PM Vincent Bernat <bernat at luffy.cx> wrote:

> Hey!
>
> I am trying to setup a Juniper QFX5100 as a VTEP with a very classic
> setup. Everything works as expected, but the setup is only using one
> possible path from the underlay network.
>
> I have the route to the other VTEP like this:
>
> # run show route 10.16.39.3
>
> inet.0: 240 destinations, 1808 routes (240 active, 0 holddown, 0 hidden)
> + = Active Route, - = Last Active, * = Both
>
> 10.16.39.3/32      *[BGP/140] 00:38:24, localpref 500, from 10.64.0.5
>                       AS path: I, validation-state: unverified
>                       to 10.64.0.23 via xe-0/0/46.181
>                     > to 10.64.128.23 via xe-0/0/47.183
>                     [BGP/140] 00:38:24, localpref 500, from 10.64.128.6
>                       AS path: I, validation-state: unverified
>                     > to 10.64.128.23 via xe-0/0/47.183
>                     [BGP/140] 00:38:24, localpref 500, from 10.64.0.3
>                       AS path: I, validation-state: unverified
>                     > to 10.64.0.23 via xe-0/0/46.181
>
> :vxlan.inet.0: 17 destinations, 21 routes (17 active, 0 holddown, 0 hidden)
> + = Active Route, - = Last Active, * = Both
>
> 10.16.39.3/32      *[Static/1] 00:31:10, metric2 0
>                     > to 10.64.128.23 via xe-0/0/47.183
>
> So, from an IP point of view, I have two available routes to the other
> VTEP. In the :vxlan.inet.0 table, only one route is kept. I suppose the
> problem is at this point.
>
> Looking at the forwarding table, I have only one indirect next-hop too:
>
> # show route forwarding-table family ethernet-switching bridge-domain
> vlan-client1-543 extensive
>    Routing table: default-switch.bridge [Index 4]
>    Bridging domain: vlan-client1-543.bridge [Index 3]
>    VPLS:
>    Enabled protocols: Bridging, ACKed by all peers,
>
> [...]
>    Destination:  0a:e3:40:00:00:d9/48
>      Learn VLAN: 0                        Route type: user
>      Route reference: 0                   Route interface-index: 575
>      Multicast RPF nh index: 0
>      P2mpidx: 0
>      IFL generation: 142                  Epoch: 0
>      Sequence Number: 0                   Learn Mask:
> 0x4000000000000000000000000000000000000000
>      L2 Flags: control_dyn
>      Flags: sent to PFE
>      Next-hop type: composite             Index: 2045     Reference: 6
>      Next-hop type: indirect              Index: 131317   Reference: 3
>      Nexthop: 10.64.128.23
>      Next-hop type: unicast               Index: 1928     Reference: 4
>      Next-hop interface: xe-0/0/47.183
>
> So, how to ensure the two possible next-hops are copied to the
> ":vxlan.inet.0" table?
> --
> Make input easy to prepare and output self-explanatory.
>             - The Elements of Programming Style (Kernighan & Plauger)
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