Re: [bess] DF election rule in EVPN MH, for untagged interface

The Ethernet Tag that you use for DF Election does not even need to match what you have in the data path.
Note that the definition says even “configured IDs”.

As long as you use the same ID for the BD on all the PEs attached to the ES, you are fine.

Thx
Jorge

From: Muthu Arul Mozhi Perumal <muthu.arul@gmail.com>
Date: Friday, April 5, 2019 at 5:10 PM
To: "Rabadan, Jorge (Nokia - US/Mountain View)" <jorge.rabadan@nokia.com>
Cc: Jaikumar Somasundaram <jaikumar.somasundaram@ericsson.com>, "bess@ietf.org" <bess@ietf.org>, P Muthu Arul Mozhi <p.muthu.arul.mozhi@ericsson.com>
Subject: Re: [bess] DF election rule in EVPN MH, for untagged interface - reg

Thanks, Jorge. It is clear that the Ethernet Tag needs to be different from 0 for the purpose of DF election..

One of the options a provider has for supporting untagged frames in EVPN VPLS multihoming in VID translation...a rule to match untagged frames and impose a VID at the ingress and another rule to match that VID and dispose it at the egress.

Are there any other options that can interop well?

Regards,
Muthu

On Fri, Apr 5, 2019 at 11:11 AM Rabadan, Jorge (Nokia - US/Mountain View) <jorge.rabadan@nokia.com<mailto:jorge.rabadan@nokia.com>> wrote:
Hi,

I think you should check out https://tools.ietf.org/html/draft-ietf-bess-evpn-df-election-framework-09

This draft updates RFC7432 in certain aspects of the DF Election, and it is already at the RFC editor.

Check out the use of Ethernet Tag in the document.

   o Ethernet Tag - used to represent a Broadcast Domain that is
     configured on a given ES for the purpose of DF election. Note that
     any of the following may be used to represent a Broadcast Domain:
     VIDs (including Q-in-Q tags), configured IDs, VNI (VXLAN Network
     Identifiers), normalized VID, I-SIDs (Service Instance
     Identifiers), etc., as long as the representation of the broadcast
     domains is configured consistently across the multi-homed PEs
     attached to that ES. The Ethernet Tag value MUST be different from
     zero.

Thanks.
Jorge

From: BESS <bess-bounces@ietf.org<mailto:bess-bounces@ietf.org>> on behalf of Jaikumar Somasundaram <jaikumar.somasundaram@ericsson.com<mailto:jaikumar.somasundaram@ericsson.com>>
Date: Friday, April 5, 2019 at 6:15 AM
To: "bess@ietf.org<mailto:bess@ietf.org>" <bess@ietf.org<mailto:bess@ietf.org>>
Cc: P Muthu Arul Mozhi <p.muthu.arul.mozhi@ericsson.com<mailto:p.muthu.arul.mozhi@ericsson.com>>
Subject: [bess] DF election rule in EVPN MH, for untagged interface - reg

Hi All,

RFC7432, section 8.5, talks about DF election algorithm (service carving algorithm)

only for <ES, VLAN> for VLAN-based service or <ES, VLAN bundle> for VLAN-(aware)
bundle service.

But there wont be any vlan id for untagged interface and so I wonder
how the service carving algorithm can be applied to elect the DF.
Also, should I use the lower VLAN ID even in the case of VLAN-bundle
service, for electing the DF?

Could some one help me to understand this please?

==========<snip from RFC 7432, section 8.5>===============
8.5<https://tools.ietf.org/html/rfc7432#section-8.5>.  Designated Forwarder Election

…

   The default procedure for DF election at the granularity of <ES,

   VLAN> for VLAN-based service or <ES, VLAN bundle> for VLAN-(aware)

   bundle service is referred to as "service carving".
…

      Assuming a redundancy group of N PE nodes, for VLAN-based service,

      the PE with ordinal i is the DF for an <ES, VLAN V> when (V mod N)

      = i.  In the case of VLAN-(aware) bundle service, then the

      numerically lowest VLAN value in that bundle on that ES MUST be

      used in the modulo function.
…
=========<snip end>======================================

Thanks & Regards
Jaikumar S

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