Re: WGLC for BFD Multipoint documents (last round)

Greg Mirsky <gregimirsky@gmail.com> Wed, 14 February 2018 02:11 UTC

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From: Greg Mirsky <gregimirsky@gmail.com>
Date: Tue, 13 Feb 2018 18:10:59 -0800
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Subject: Re: WGLC for BFD Multipoint documents (last round)
To: "Carlos Pignataro (cpignata)" <cpignata@cisco.com>
Cc: "gregory.mirsky@ztetx.com" <gregory.mirsky@ztetx.com>, "Reshad Rahman (rrahman)" <rrahman@cisco.com>, "rtg-bfd@ietf.org" <rtg-bfd@ietf.org>
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Hi Carlos,
thank you for your prompt response to the proposed updates. Indeed, I've
missed your comment. Please find my follow-up updates under GIM2>> tag.
I've attached diff to highlight the changes.

Regards,
Greg

On Tue, Feb 13, 2018 at 3:37 PM, Carlos Pignataro (cpignata) <
cpignata@cisco.com>; wrote:

> Hi, Greg,
>
> On Feb 11, 2018, at 9:03 PM, Greg Mirsky <gregimirsky@gmail.com>; wrote:
>
> Hi Carlos,
> thank you for your thorough review and detailed comments.
>
>
> Anytime — but just to be clear, this is not a thorough review. I spent a
> quick scan through some sections only, which triggered these coarse set of
> comments.
> GIM2>> Still, many thanks. And it would be of great help if you can find
> time to do more detailed review and share your comments to both documents.
>
> Please find my responses in-lined tagged GIM>>.
>
>
> More inline.
>
> Regards,
> Greg
>
> On Thu, Feb 8, 2018 at 7:19 PM, Carlos Pignataro (cpignata) <
> cpignata@cisco.com>; wrote:
>
>> Hi, Greg,
>>
>> When looking for this specific sentence, I got a chance to scan through
>> the document a bit.
>>
>> It seems to me there are still a number of editorials and potentially
>> non-editorials to be fixed.
>>
>> Looking at S4.8 only:
>>
>>    BFD packets received on tails for an IP multicast group MUST be
>>    consumed by tails and MUST NOT be forwarded to receivers.  Session of
>>    type MultipointTail MUST identify the packet as BFD with the help of
>>    destination UDP port number "3784" on IP multipoint path.
>>
>> CMP: There are a number of “the” or “a[n]” articles missing.
>>
>> CMP: What is “with the help of”? What is "port number "3784" on IP
>> multipoint path”?
>>
> GIM>> Agree, will remove the quotation marks around 3784. Proposed update:
> OLD TEXT:
>  Session of
>    type MultipointTail MUST identify the packet as BFD with the help of
>    destination UDP port number "3784" on IP multipoint path.
> NEW TEXT:
> Session of type MultipointTail MUST identify packet received on an IP
> multipoint path
> as BFD control packet if the destination UDP port value equals 3784.
>
>
> Who identifies the packets? The "session"? Or should this be the
> tail/receiver/tailend?
>
> GIM2>> Would the following clarify it:
>


OLD TEXT:
 Session of
   type MultipointTail MUST identify the packet as BFD with the help of
   destination UDP port number "3784" on IP multipoint path.
NEW TEXT:

Node with
   the BFD session of type MultipointTail MUST identify packet received
   on an IP multipoint path as BFD control packet if the destination UDP
   port value equals 3784.



>>    For multipoint LSPs, when IP/UDP encapsulation of BFD control packets
>>    is used, MultipointTail MUST use destination UDP port "3784" and
>>    "127.0.0.0/8" range for IPv4 or "0:0:0:0:0:FFFF:7F00:0/104" range for
>>    IPv6 ([RFC8029]).  Packets identified as BFD packets MUST be consumed
>>    by MultipointTail and demultiplex as described in Section 4.13.2
>> .
>> CMP: The first sentence is very confusing (besides the “MUST use” that
>> you already called out and that I agree).
>> CMP: For example, is this the source or destination endpoint? Which
>> address is this (i.e., Destination)?
>>
> GIM>> Since the sentence refers to MultipointTail, I conclude this refers
> to the destination endpoint. As Reshad agreed to s/use/expect/
> here's proposed update to the sentence:
> OLD TEXT:
>    For multipoint LSPs, when IP/UDP encapsulation of BFD control packets
>    is used, MultipointTail MUST use destination UDP port "3784" and
>    "127.0.0.0/8" range for IPv4 or "0:0:0:0:0:FFFF:7F00:0/104" range for
>    IPv6 ([RFC8029]).
> NEW TEXT:
>    For multipoint LSPs, when IP/UDP encapsulation of BFD control packets
>    is used, MultipointTail MUST expect destination UDP port 3784 and
>    destination IP address in 127.0.0.0/8 range for IPv4 or
> 0:0:0:0:0:FFFF:7F00:0/104 range for
>    IPv6 ([RFC8029]).
>
> GIM2>> I hope I've got it now:


OLD TEXT:
   For multipoint LSPs, when IP/UDP encapsulation of BFD control packets
   is used, MultipointTail MUST use destination UDP port "3784" and
   "127.0.0.0/8" range for IPv4 or "0:0:0:0:0:FFFF:7F00:0/104" range for
   IPv6 ([RFC8029]).
NEW TEXT:
   For multipoint LSPs, when IP/UDP encapsulation of BFD control packets
   is used, MultipointTail MUST expect destination UDP port 3784.
   Destination IP address of BFD control packet MUST be in 127.0.0.0/8
   range for IPv4 or in 0:0:0:0:0:FFFF:7F00:0/104 range for IPv6
([RFC8029]).


>
> In addition to pointing to RFC 8029, for things like Section 2.1, etc.,
> this is a new requirement. RFC 8029 does not specify the use of those IP
> addresses with UDP Port 3784. Hence the citation should go on a separate
> sentence.
>
>
>>    Use of other types of encapsulation for multipoint LSP is outside the
>>    scope of this document.
>>
>> CMP: For BFD Control?
>>
> GIM>> Will add 'of the BFD control message over' and remove 'for' to
> result:
> Use of other types of encapsulation of the BFD control message over
> multipoint LSP  is outside the scope of this document.
>
>
> Thanks.
>
>
>> Also, checking the following section:
>>
>> 4.13.1.  Reception of BFD Control Packets
>>
>>    The following procedure replaces section 6.8.6 of [RFC5880].
>> …
>>       If bfd.SessionType is PointToPoint, update the Detection Time as
>>       described in [RFC5880] section 6.8.4.  Otherwise, update the
>>       Detection Time as described in Section 4.11 above.
>>
>> CMP: The actual set of citations is not clear. If this is a replacement
>> to section 6.8.6 of [RFC5880], then why a citation like “[RFC5880] section
>> 6.8.4"? Isn’t it implied that it is RFC 5880? Or conversely, if it is a
>> replacement updating RFC 5880, how does “in Section 4.11 above” work when
>> inserted in RFC 5880? Its ask relative :-)
>>
>>
> Seems you missed this comment.
>
GIM2>> Right. The text requires update:
OLD TEXT:
       If bfd.SessionType is PointToPoint, update the Detection Time as
      described in [RFC5880] section 6.8.4.  Otherwise, update the
      Detection Time as described in Section 4.11 above.
NEW TEXT:
      If bfd.SessionType is PointToPoint, update the Detection Time as
      described in section 6.8.4 of [RFC5880].  If bfd.SessionType is
      MultipointTail, then update the Detection Time as described in
      Section 4.11.

GIM2>> RE: references to RFC 5880 in this section. I think that they are
useful as long as this is separate document. Once someone will decide to do
5880bis and in fact replace section 6.8.6, the references should be removed.

>
> Thanks!
>
> Carlos.
>
>
>
> Thanks!
>>
>> —
>> Carlos Pignataro, carlos@cisco.com
>>
>> *“Sometimes I use big words that I do not fully understand, to make
>> myself sound more photosynthesis."*
>>
>> On Feb 8, 2018, at 12:14 AM, gregory.mirsky@ztetx.com wrote:
>>
>> Hi Reshad,
>>
>> thank you for your consideration. I've came across what looks as simple
>> editorial change. Appreciate your comment.
>>
>> In the second paragraph of section 4.8 Packet consumption on tails the
>> following
>>
>>   For multipoint LSPs, when IP/UDP encapsulation of BFD control packets
>>
>>   is used, MultipointTail MUST use destination UDP port "3784" ...
>>
>> reads akwardly because, I think, of 'MUST use'. I propose simple
>> s/use/look for/ or s/use/expect/. What do you think? Is the text god as-is
>> or minor editing may help?
>>
>>
>> Regards,
>>
>> Greg Mirsky
>>
>>
>> Sr. Standardization Expert
>> 预研标准部/有线研究院/有线产品经营部 Standard Preresearch Dept./Wireline Product R&D
>> Institute/Wireline Product Operation Division
>>
>>
>>
>> <9ae3e214c17d49ed935d87c674ba3ee2.jpg> <24242e5637af428891c4db731e776
>> 5ad.jpg>
>> E: gregory.mirsky@ztetx.com
>> www.zte.com.cn
>> Original Mail
>> *Sender: *ReshadRahman(rrahman) <rrahman@cisco.com>;
>> *To: *gregory mirsky10211915;rtg-bfd@ietf.org <rtg-bfd@ietf.org>;
>> *Date: *2018/02/08 11:03
>> *Subject: **Re: WGLC for BFD Multipoint documents (last round)*
>>
>> <Sorry for the delay>
>>
>> Hi Greg,
>>
>>
>>
>> I would go with normative SHOULD. What you proposed below is fine.
>>
>>
>>
>> Regards,
>>
>> Reshad.
>>
>>
>>
>>
>>
>> *From: *"gregory.mirsky@ztetx.com"; <gregory.mirsky@ztetx.com>;
>> *Date: *Sunday, February 4, 2018 at 8:33 PM
>> *To: *"Reshad Rahman (rrahman)" <rrahman@cisco.com>;, "rtg-bfd@ietf.org"; <
>> rtg-bfd@ietf.org>;
>> *Subject: *Re: WGLC for BFD Multipoint documents (last round)
>>
>>
>>
>> Hi Reshad,
>>
>> you've said:
>>
>> Hi Greg,
>>
>>
>>
>> While OOB mechanism would improve security, my personal opinion is that we should try to improve security without requiring an OOB mechanism. I think we can add text to the security considerations to address the concerns below, e.g. A tail SHOULD prevent the number of MultipointTail sessions from exceeding the number of expected streams.  The concern expressed in b) cannot be fixed by what I proposed because of multiple streams.  So just preventing the number of MultipointTail sessions from exceeding the number of expected streams should be good enough.
>>
>>
>>
>> Regards,
>>
>> Reshad.
>>
>>
>>
>> If we make it normative SHOULD, i.e. s/should/SHOULD/ in the third
>> recommendation to the implementers:
>>
>>      The implementation SHOULD have a reasonable upper bound on the
>>
>>       number of MultipointTail sessions that can be created, with the
>>
>>       upper bound potentially being computed based on the number of
>>
>>       multicast streams that the system is expecting.
>>
>>
>>
>> Or keep the lower case as it is consistent with the rest of the section,
>> e.g. 'a MultipointTail session should not be created'?
>>
>>
>>
>> Kind regards,
>>
>> Greg Mirsky
>>
>>
>>
>> Sr. Standardization Expert
>> 预研标准部/有线研究院/有线产品经营部 Standard Preresearch Dept./Wireline Product R&D
>> Institute/Wireline Product Operation Division
>>
>>
>>
>> <image001.gif>
>>
>> <image002.gif>
>> E: gregory.mirsky@ztetx.com
>> www.zte.com.cn
>>
>>
>