EVPN static IMET route on Bird 3.3.0

[André Grüneberg]

Dear Maria, dear all,

I believe, I managed to make it work.

Before starting bird:
ip link add name vx7 type vxlan id $VNI local $ROUTER dstport 4789
ip link set vx7 up

bird.conf:
eth table t_eth;
evpn table t_evpn;
protocol evpn p_ixpect01 {
        evpn { table t_evpn; };
        eth { table t_eth; };
        rd my_ip:100;
        route target (rt, 10, 100);
        encapsulation vxlan {
                tunnel device "vx7";
        };
}

So it takes a whole protocol to inject a static entry -- with the
limitation of one IMET route per VNI.

BTW: In case the vxlan Interface does not exist, Bird 3.3.0 on Ubuntu 26.04
does crash with a segfault in libc:

kernel: bird[236863]: segfault at 10 ip 00007963a6b9a1af sp
00007ffe6a8cda38 error 4 in libc.so.6[19a1af,7963a6a28000+198000] likely on
CPU 1 (core 2, socket 0)
kernel: Code: 2e 0f 1f 84 00 00 00 00 00 66 90 f3 0f 1e fa c4 41 01 ef ff
89 f8 09 f0 c1 e0 14 3d 00 00 00 f8 0f 87 25 03 00 00 c5 fe 6f 07 <c5> fd
74 0e c5 85 74 d0 c5 ed df c9 c5 fd d7 c9 ff c1 74 5d f3 0f

Is this considered a bug? ;)

Best wishes,
André

On Thu, 28 May 2026 at 10:06, Maria Matejka <maria.matejka at nic.cz> wrote:

> Hello André,
>
> thank you for checking out our EVPN implementation. If I remember
> correctly, we didn’t think about injecting totally static information, and
> therefore I’m afraid there is no easy way around this for now.
> Specifically, it doesn’t look possible to me to get an EVPN protocol
> without the VXLAN device, as it has to generate FDB records using that
> device.
>
> You may try changing the type from T_OPAQUE to T_BYTESTRING in
> proto/bgp/attrs.c (and building yourself), that should make it (for 3.3.0)
> accessible for setting to custom values by filters. We didn’t do that
> simply because we want to update the filter language to systematically
> support structured data, and this would be yet another quirk to take care
> about later and possibly carry forward to far future.
>
> Maybe Ondřej has better ideas later today, let’s see.
>
> I hope this helps.
> Happy experimenting!
> Maria
>
> On Thu, May 28, 2026 at 08:57:50AM +0200, André Grüneberg wrote:
>
> Hi again,
>
> I have tried a few things and looked at a bit of code.
>
> By now I learned from documentation that I cannot create a custom
> attribute – bgp_pmsi_tunnel already exists. And I cannot assign a
> bytestring – the documentation says it’s not accessible in filters. Since
> the route attribute is of T_OPAQUE, I also cannot assign a value in the
> static route.
>
> The only place in the code accessing bgp_pmsi_tunnel is in
> evpn_announce_imet(). So it seems I will need a minimal protocol evpn in my
> config. Can I build one without having all the vxlan interfaces? Note: I
> need the router address to be another system.
>
> Thanks, André
>
> On Wed, 27 May 2026 at 17:12, André Grüneberg andre.grueneberg at bcix.de
> wrote:
>
> Hi bird users,
>
> I am currently experimenting with Bird 3.3.0 and EVPN. I do not need/want
> a local termination, but want to inject static EVPN routes only.
>
> Despite missing documentation (hint!), I found the necessary syntax to
> define mac-ip and imet routes. I also managed to manually set the required
> ext communities (tunnel type, MAC mobility, RT) as well as the VNI
> (mpls_label) in the filter.
>
> What remains open is the bgp_pmsi_tunnel attribute. According to the
> documentation it’s not available in filters.
>
> Is there any alternative way to statically set it? Maybe a custom
> attribute and a binary string?
>
> Thanks, André
>
> – André Grüneberg, Managing Director andre.grueneberg at bcix.de
>
> +49 30 2332195 42
>
> BCIX Management GmbH Albrechtstr. 110 12103 Berlin Germany
>
> Geschäftsführer/Managing Directors: Jens Lietzmann, André Grüneberg
> Handelsregister: Amtsgericht Charlottenburg, HRB 143581 B
>
> –
> André Grüneberg, Managing Director andre.grueneberg at bcix.de +49 30
> 2332195 42
>
> BCIX Management GmbH Albrechtstr. 110 12103 Berlin Germany
>
> Geschäftsführer/Managing Directors: Jens Lietzmann, André Grüneberg
> Handelsregister: Amtsgericht Charlottenburg, HRB 143581 B
>
> –
> Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.
>


-- 
André Grüneberg, Managing Director
andre.grueneberg at bcix.de
+49 30 2332195 42

BCIX Management GmbH
Albrechtstr. 110
12103 Berlin
Germany

Geschäftsführer/Managing Directors: Jens Lietzmann, André Grüneberg
Handelsregister: Amtsgericht Charlottenburg, HRB 143581 B
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