Re: [bess] Alia Atlas' Discuss on draft-ietf-bess-evpn-vpws-11: (with DISCUSS and COMMENT)

[Sami Boutros <[e-mail]>]

Hi Alia,

Please see comments inline.


On 4/11/17, 4:43 PM, "Alia Atlas" <[e-mail]> wrote:

>Alia Atlas has entered the following ballot position for
>draft-ietf-bess-evpn-vpws-11: Discuss
>
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>
>
>----------------------------------------------------------------------
>DISCUSS:
>----------------------------------------------------------------------
>
>First, thank you for a clearly written document that contained enough
>context to trigger my hazy
>memory of some of the technical details.
>
>My concern is around this paragraph in the Introduction:
>
>"The MPLS label value in the Ethernet A-D route can be set to the
>   VXLAN Network Identifier (VNI) for VXLAN encap, and this VNI may
>have
>   a global scope or local scope per PE and may also be equal to the
>   VPWS service instance identifier set in the Ethernet A-D route.
>"
>
>First, I recognize that folks have implemented and deployed EVPN with
>VXLAN.
>That's fine.  There is an ISE RFC 7348 that describes VXLAN.   Depending
>on what
>you (authors, shepherd, AD, WG) decide to do about the rest of my
>concern, it is
>likely that this should be normative references - which would be a
>downref.

I can add the 7348 as a normative reference.

>
>Second, the paragraph here isn't really adequate to describe how to
>implement the
>functionality.   I don't see how:
>    a) The ingress PE decides which VNIs it can send based upon the
>VNI=MPLS_label
>        from the egress.   Is there an assumption that VXLAN allows
>sending all VNIs across
>        the particular VPWS, whether port-based, VLAN-based, etc?

We are signaling Ethernet A-D route per VPWS instance, and in there we will signal 
VNI instead of an MPLS label for VxLAN encap.

>    b) Is there an assumption that the egress PE-advertised MPLS label
>also indicates the
>         VNI to be used?  

EVPN can work with different encapsulations a BGP Tunnel Encapsulation Attribute 
That specifies the tunnel type will be added to the Ethernet A-D route.


>That seems like another mode, like the
>VLAN-based service, except
>         it is perhaps VNI + VLAN-based service?

The draft lists clearly the different service interface types, and there will 
be only one VNI per VPWS instance wether this is Vlan or port based.

>
>Please don't take this Discuss as a reason to remove the paragraph and
>the implied functionality.
>If it's implemented and deployed (and I think it is) - then what I really
>want is to just have it
>adequately written down so that others can interoperably implement.  The
>downref to VXLAN
>should just be a matter of process nuisance (i.e. another IETF Last Call
>and handling any concerns).
>

Should I add the 7348 as a normative reference?



>
>----------------------------------------------------------------------
>COMMENT:
>----------------------------------------------------------------------
>
>1) (Nit) Sec 3.1 "This draft" for an RFC should be "This document" or
>"This specification" or...

Will fix.
>
>2) Sec 3.1:  "    C      If set to 1, a Control word [RFC4448] MUST be
>present when sending EVPN packets to this PE."
>   Given discussions with IEEE about real MACs starting with 4 and 6 in
>top nibble, adding a statement about it being BCP to include
>   the control word (unless using Entropy Label) would be a good idea.
>
Could you suggest some text? 

Should I submit -12 with the changes?

Thanks,

Sami
>