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

["Ali Sajassi (sajassi)" <[e-mail]>]

Jeffrey,



On 2/1/16, 2:41 PM, "Jeffrey (Zhaohui) Zhang" <[e-mail]> wrote:

>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.

We’ll do.

Cheers,
Ali

>
>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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>> >
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