[bess] Opsdir last call review of draft-ietf-bess-evpn-etree-12

Carlos Pignataro <cpignata@cisco.com> Mon, 07 August 2017 21:46 UTC

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From: Carlos Pignataro <cpignata@cisco.com>
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Date: Mon, 07 Aug 2017 14:46:16 -0700
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Subject: [bess] Opsdir last call review of draft-ietf-bess-evpn-etree-12
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Reviewer: Carlos Pignataro
Review result: Has Issues

Reviewer: Carlos Pignataro
Review result: Has Nits (and one potential Issue)

I am the OPS-DIR reviewer and in general I do not have operational concerns
with this document.

The main issue I have is in regards to the redefinition of the MSB of the
Tunnel Type, and associated backwards/forward compatibility considerations.

I note that RFC 7385 is Normatively referenced by a number of I-Ds:
https://datatracker.ietf.org/doc/rfc7385/referencedby/
BUT draft-ietf-bess-evpn-etree is not:
https://datatracker.ietf.org/doc/draft-ietf-bess-evpn-etree/referencedby/

So would those former be pointing to old info? And what other Backwards Compat
considerations are there?

Further, some nits and editorials for your consideration:

   The Metro Ethernet Forum (MEF) has defined a rooted-multipoint
   Ethernet service known as Ethernet Tree (E-Tree). A solution
   framework for supporting this service in MPLS networks is proposed in
   RFC7387 ("A Framework for Ethernet Tree (E-Tree) Service over a
   Multiprotocol Label Switching (MPLS) Network").

Proposed? Or Described / Defined?

Same comment for the first sentence of the second paragraph of the Intro.

   This document makes use of the
   most significant bit of the scope governed by the IANA registry
   created by RFC7385, and hence updates RFC7385 accordingly.

RFC 7385 does not mention a "scope". This really talks about the Tunnel Type.
Please reword for unambiguous clarity.

3.1 Known Unicast Traffic

   To support the above ingress filtering functionality, a new E-TREE
   Extended Community with a Leaf indication flag is introduced [section
   5.2]. This new Extended Community MUST be advertised with MAC/IP

Section 5.2 is not a referenced citation.

Similar issue with [5.1] at:

   In PBB-EVPN, the PE advertises a Root/Leaf indication along with each
   B-MAC Advertisement route, to indicate whether the associated B-MAC
   address corresponds to a Root or a Leaf site. Just like the EVPN
   case, the new E-TREE Extended Community defined in section [5.1] is
   advertised with each MAC Advertisement route.

3.2 BUM Traffic

Please expand to Broadcast, Unkonwn, Multicast.

   When receiver ingress-replication label is needed, the high-order bit
   of the tunnel type field (Composite Tunnel bit) is set while the
   remaining low-order seven bits indicate the tunnel type as before.

I believe it would be useful to depict the Composite Tunnel bit in Figure 5 as
well... It's not only a 1-octet Type.

Also, please note:

  ** Obsolete normative reference: RFC 5226

  ** Downref: Normative reference to an Informational RFC: RFC 7387

Thank you!

Carlos.