Re: [bess] WG Last Call on draft-ietf-bess-evpn-etree

["Jeffrey (Zhaohui) Zhang" <[e-mail]>]

Ali,

One more question about PBB-EVPN.

For the regular EVPN, section 3.3.2 talks about a situation where the only traffic is BUM. There is no need for mac learning in that situation.

For PBB-EVPN, I assume this is also possible. With this, there is no need to advertise per-ES B-mac addresses - a single pair of global root/leaf B-mac addresses are enough.

Perhaps this can be mentioned for parity/completeness. Of course, this is not a big deal and either way it's fine - but I do want to ask to confirm my understanding.

Jeffrey

> -----Original Message-----
> From: Ali Sajassi (sajassi) [mailto:[e-mail]]
> Sent: Monday, February 01, 2016 2:04 AM
> To: Jeffrey (Zhaohui) Zhang <[e-mail]>; EXT -
> [e-mail] <[e-mail]>; BESS <[e-mail]>;
> [e-mail]
> Subject: Re: [bess] WG Last Call on draft-ietf-bess-evpn-etree
> 
> Hi Jeffrey,
> 
> Thanks for the review. Your comments helps tighten the draft some more. I
> have updated the draft and will publish it next (rev04). Majority of the
> comments were editorial in nature for better clarifications. Since the
> existing draft (rev03) reflects the consensus regarding our several rounds
> of discussions where we have taken care of the technical items, it is
> consistent with our expectation of not seeing any major issue during the
> LC. Please refer to my replies in line.
> 
> Cheers,
> Ali
> 
> 
> On 1/27/16, 5:26 PM, "BESS on behalf of Jeffrey (Zhaohui) Zhang"
> <[e-mail] on behalf of [e-mail]> wrote:
> 
> >I was involved in relevant discussions, and have reviewed once more for
> >this LC.
> >
> >I support the publication, but with the following questions/comments.
> >
> >2.1 Scenario 1: Leaf OR Root site(s) per PE
> >
> >   ... If the number of EVIs is very large
> >   (e.g., more than 32K or 64K), then RT type 0 as defined in [RFC4360]
> >   SHOULD be used; otherwise, RT type 2 is sufficient.
> >
> >RFC 7153 should be referenced for "Type 2".
> 
> 
> Done.
> 
> >
> >Additionally, why is 32K mentioned? I can understand the 64k part.
> 
> Removed 32K since the example is clear enough with 64K
> 
> >
> >   ... the MPLS-encapsulated frames MUST be tagged with an
> >   indication of whether they originated from a Leaf AC or not.
> >
> >Perhaps change the last line to "indication if they originated from a
> >Leaf AC"? Packets from a root AC are not tagged with a leaf indication.
> 
> OK. Better yet. It should say ³indication when they originated from a leaf
> AC².
> 
> >
> >   Other mechanisms for identifying whether an egress AC is a root or
> >   leaf is beyond the scope of this document.
> >
> >Should "egress" be "ingress" in the above paragraph? Or simply removed?
> 
> Nice catch! It is ³ingress². It is now corrected.
> 
> >
> >   ... This Leaf MPLS label is advertised to other PE devices,
> >   using a new EVPN Extended Community called E-TREE Extended Community
> >   (section 5.1) along with an Ethernet A-D per ES route with ESI of
> >   zero and a set of Route Targets (RTs) corresponding to all the leaf
> >   ACs on the PE.
> >
> >Perhaps change the last sentence to "... corresponding to all EVIs that
> >have leaf sites on the PE."
> 
> The second to last sentence of section 3.2.1 says the same thing. I
> changed this sentence and removed the 2nd to last sentence.
> 
> >
> >3.2.3 BUM traffic originated from a multi-homed site on a leaf AC
> >
> >   In this scenario, it is assumed that a multi-homed Ethernet Segment
> >   (ES) can have a mixed of both leaf and root ACs with each AC
> >   designating a subnet (e.g., a VLAN).
> >
> >I understand that different VLANs on the same ES could be roots or
> >leaves. I suppose it's more important to say that for the same vlan,
> >different PEs on the same ES must have the same root/leaf designation.
> 
> That¹s given.
> 
> >
> >Perhaps the first sentence could be reworded as the following to capture
> >the above point:
> >
> >   While different ACs (VLANs) on the same ES could have different
> >   root/leaf designation (some being roots and some being leaves),
> >   the same VLAN does have the same root/leaf designation on all
> >   PEs on the same ES.
> 
> That¹s fine. It makes it more clear.
> 
> >
> >For the following:
> >
> >   ... the PEs with Leaf sites perform MAC learning in the
> >   data-path over their Ethernet Segments, and advertise reachability in
> >   EVPN MAC Advertisement routes which are imported only by PEs with at
> >   least one Root site in the EVI. A PE with only Leaf sites will not
> >   import these routes. PEs with Root and/or Leaf sites may use the
> >   Ethernet A-D routes for aliasing (in the case of multi-homed
> >   segments) and for mass MAC withdrawal per [RFC 7432].
> >
> >The above seems to contradict with the recommendation in Section 2.2. If
> >the context is the scenario described in section 2.1 then that's fine,
> >but the text does not have a clear context.
> 
> Agreed. Updated the section to indicate the context is section 2.1.
> 
> >
> >
> >3.3.2 E-Tree without MAC Learning
> >
> >   The PEs implementing an E-Tree service need not perform MAC learning
> >   when the traffic flows between Root and Leaf sites are multicast or
> >   broadcast.
> >
> >I suppose an "only" word should be added at the end of the above sentence.
> 
> Agreed.
> 
> >
> >
> >   The fields of the IMET route are populated per the procedures defined
> >   in [RFC7432], and the route import rules are as described in previous
> >   sections.
> >
> >The route import rules described in previous sections are for MAC routes,
> >not IMET routes. Additionally, those rules may not be recommended, so
> >might as well delete the last sentence.
> 
> Changed the last sentence to ³Š, and the multicast tunnel setup criteria
> are as described in the previous section.²
> 
> >
> >Section 3.3.1 talks about BUM procedures. That is not specific to 3.3.1
> >though. Perhaps extract that out to a separate section, and remove the
> >BUM text from 3.3.2 as well.
> 
> I think it is OK.
> 
> >
> >   The E-TREE Extended Community is encoded as an 8-octet value as
> >   follows:
> >
> >
> >        0                   1                   2                   3
> >        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
> >       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >       | Type=0x06     | Sub-Type=0x04 | Flags(1 Octet)|               |
> >       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >       |  Reserved=0   |           Leaf Label                          |
> >       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >
> >I assume the octect after the flags octet is also reserved=0. Better mark
> >it as "Reserved=0".
> 
> Agreed.
> 
> >
> >When it is used with Ethernet A-D per ES route, the leaf flag SHOULD be
> >set to 0 but ignored by the receiving routers. Therefore, why not set it
> >to 1 to be consistent the MAC/IP route case?
> 
> Because the flag is used for known unicast traffic and Leaf label for BUM
> traffic. We don¹t want to mix the two.
> 
> Cheers,
> Ali
> 
> >
> >Thanks.
> >Jeffrey
> >
> >> -----Original Message-----
> >> From: BESS [mailto:[e-mail]] On Behalf Of Thomas Morin
> >> Sent: Tuesday, January 19, 2016 3:51 AM
> >> To: BESS <[e-mail]>; [e-mail]
> >> Subject: [bess] WG Last Call on draft-ietf-bess-evpn-etree
> >>
> >> Hello Working Group,
> >>
> >> This email starts a Working Group Last Call on
> >> draft-ietf-bess-evpn-etree [1] which is considered mature and ready for
> >> a final working group review.
> >>
> >> Please read the document if you haven't read the most recent version
> yet
> >> (-03), and send your comments to the list, no later than *February the
> >> 2nd* (2016-02-02).
> >>
> >> This is not only a call for comments on the document, but also a call
> of
> >> support for its publication.
> >>
> >> *Coincidentally*, we are also polling for knowledge of any IPR that
> >> applies to draft-ietf-bess-evpn-etree, to ensure that IPR has been
> >> disclosed in compliance with IETF IPR rules (see RFCs 3979, 4879, 3669
> >> and 5378 for more details).
> >>
> >> *If* you are listed as a document author or contributor of
> >> draft-ietf-bess-evpn-etree please respond to this email and indicate
> >> whether or not you are aware of any relevant IPR.
> >>
> >> Thank you,
> >>
> >> Thomas/Martin
> >>
> >> [1] https://datatracker.ietf.org/doc/draft-ietf-bess-evpn-etree
> >>
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