[j-nsp] Advertising inactive routes to iBGP neighbors

[James]

Hi Nathan,

The only reason I'm using EVPN-VXLAN is for ESI LAG multihoming to the
server. In this particular setup, the spines do not do any VXLAN
encap/decap and act only as BGP RR's for the leaf switches.

The static /32 route is necessary to allocate IP address(es) to the
server. I'm treating it as if it were any standard layer 3 network,
except the next-hop interface in this case just happens to be an irb
that is the l3-interface for a VXLAN. Since all this is happening on
the leaf switches, I need to somehow redistribute this routing
information to the spines.

Thanks,
James

On Mon, Apr 18, 2022 at 1:21 AM Nathan Ward <nward at daork.net> wrote:
>
>
> On 18/04/2022, at 3:49 AM, James via juniper-nsp <juniper-nsp at puck.nether.net> wrote:
>
>
> From: James <james at nexril.net>
> Subject: Advertising inactive routes to iBGP neighbors
> Date: 18 April 2022 at 3:49:44 AM NZST
> To: juniper-nsp at puck.nether.net
>
>
> Hi all,
>
> I have two routes in inet.0, neither of which come from BGP:
>
> 10.200.7.2/32      *[Static/5] 00:14:40
>
> to 10.200.7.2 via irb.102
>
>                    [EVPN/7] 00:08:25
>
> via irb.102
>
>
> I want to advertise the 'EVPN/7' route, either alongside or completely in place
> of the 'Static/5' route. The particular use case here is EVPN-VXLAN virtual
> machine traffic optimization, where I want to advertise the EVPN route with a
> higher localpref to steer traffic towards one or more particular leaf switches
> while still advertising the static route as a fallback in case the EVPN route
> is not there. Normally this works because the attached prefixes are longer than
> a /32, but I just can't seem to figure out how to make this work with /32
> statically routed prefixes.
>
> I've already tried several methods including rib-groups to bring the route into
> another table (no support for rib-groups with EVPN routes), bgp add-path
> (doesn't advertise the second path), and playing with route preferences
> (static route needs to be the active route for forwarding purposes), but none
> of those have been successful.
>
> Any other suggestions on how I could achieve this?
>
>
> I’m not sure I entirely understand the purpose behind what you’re doing. I read the follow up message and still don’t quite get why you need a static to make this happen, but.. is the /32 thing because in JunOS by default doesn’t advertise /32s in EVPN?
>
> You can change this with policy in protocols evpn ip-prefix-routes export <blah>.
>
> https://www.juniper.net/documentation/us/en/software/junos/evpn-vxlan/topics/ref/statement/ip-prefix-routes-edit-routing-instances-protocols-evpn.html
>
> --
> Nathan Ward
>