EVPN/VXLAN: wrong VXLAN VNI encoding in MAC routes

[Thomas Morin]

In the MAC routes advertized by bagpipe-bgp for EVPN/VXLAN, the VXLAN VNI is 4-bit left shifted like an MPLS label would be. This is incorrect and needs to be fixed to properly interop.

[Thomas Morin (tmmorin-orange)]

The symmetric issue happens on MAC route reception.

[Thomas Morin (tmmorin-orange)]

The fix requires ExaBGP 4.0.4, in which access to the unshifted value of the MPLS field has been added.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/521042
Committed: https://git.openstack.org/cgit/openstack/networking-bagpipe/commit/?id=5ec0fca978c7d3140c82eb5a2829ae33bfd81ef2
Submitter: Zuul
Branch: master

commit 5ec0fca978c7d3140c82eb5a2829ae33bfd81ef2
Author: Thomas Morin <email address hidden>
Date: Thu Nov 16 16:38:42 2017 +0100

    bagpipe-bgp: EVPN/VXLAN interop fix

    We need to interpret the content of EVPN routes based on whether the
    dataplane is VXLAN or not: if it is, then we need to read the raw value,
    not the 4-bit shifted value that applies for an MPLS label.

    Similarly in the routes we advertise, we must avoid 4-bit shifting the
    VXLAN VNI value.

    These changes require modification in ExaBGP encoding/decoding classes,
    and result in requiring ExaBGP > 4.0.2 (unreleased yet) [1].

    [1] https://github.com/Exa-Networks/exabgp/pull/744

    Closes-Bug: 1732668
    Change-Id: I3e73ed30dc2936820a50518a1d7a18d34f5a0e65

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/networking-bagpipe 8.0.0.0b3 development milestone.