Re: [PATCH proxmox-ve-rs v2 1/7] sdn: fabric: add BGP protocol support

[Gabriel Goller <g.goller@proxmox.com>]

On 15.04.2026 13:11, Hannes Laimer wrote:
> From: Stefan Hanreich <s.hanreich@proxmox.com>
> 
> Add BGP as a fabric protocol for eBGP unnumbered underlays. Each node
> has a mandatory, globally unique ASN for interface-based eBGP peering.
> 
> Unlike OSPF and OpenFabric, BGP does not have its own FRR daemon -

This is a bit wrong, BGP has its own frr daemon, maybe rewrite this as "the bgp
router is not exclusive to the bgp fabric"?

> the fabric config needs to coexist with EVPN in a single 'router bgp'
> block. To handle this, the fabric merges into an existing router
> rather than replacing it, using local-as to present the per-node ASN
> to underlay peers when the router already runs under the EVPN ASN.
> 
> For IPv6-only nodes, the BGP router-id is derived from the IPv6
> address using FNV-1a, since router-id must be a 32-bit value.

Hmm this is a bit weird since the generated address is not really reachable
right?

How do we handle this (frr bgp docs)?:

 To derive system-IP and anycast-IP, the default BGP instance’s router-id is
 used as system-IP and the VxLAN interface’s local tunnel IP as the anycast-IP.


Would it be stupid to select a ipv4 address, set it on the lo interface and then
just use update-source and set the ipv6 address?

> Co-authored-by: Hannes Laimer <h.laimer@proxmox.com>
> Signed-off-by: Stefan Hanreich <s.hanreich@proxmox.com>
> Signed-off-by: Hannes Laimer <h.laimer@proxmox.com>

Maybe a few more tests with other existing fabrics, e.g. ospf and openfabric?
These are quite easy to add, so adding a few more won't hurt.