Re: Feedback on draft-hu-bier-bfd-02

Greg Mirsky <gregimirsky@gmail.com> Thu, 08 November 2018 05:20 UTC

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From: Greg Mirsky <gregimirsky@gmail.com>
Date: Thu, 8 Nov 2018 12:20:43 +0700
Message-ID: <CA+RyBmWay60qZWifDw9LSEK_ufap64GJ_7YAB+r33DSGPmDx0A@mail.gmail.com>
Subject: Re: Feedback on draft-hu-bier-bfd-02
To: hu.fangwei@zte.com.cn
Cc: "Reshad Rahman (rrahman)" <rrahman@cisco.com>, draft-hu-bier-bfd@ietf.org, BIER WG <bier@ietf.org>, rtg-bfd WG <rtg-bfd@ietf.org>
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Apologies for the duplicate.
Now with the corrected BFD WG alias.

On Thu, Nov 8, 2018 at 12:18 PM Greg Mirsky <gregimirsky@gmail.com> wrote:

> Hi Reshad,
> thank you for taking the time to review and sharing your comments, much
> appreciated. I'll add to answers by Fangwei, please find them in-line
> tagged GIM>>.
>
> Regards,
> Greg
>
> On Thu, Nov 8, 2018 at 11:27 AM <hu.fangwei@zte.com.cn> wrote:
>
>> Hi, Rahman
>>
>> Thanks for your comments.
>>
>> Plese see inline marked with[hfw].
>>
>>
>> >Hi,
>>
>>
>>
>> >I just took a quick look at the draft:
>>
>> >1.Section 1, 2nd paragraph mentions “…detect unicast failures..”, I
>> believe this  should be unidirectional?
>>
>> [hfw] Agree, the BFD multipoint document only defines the unidirectional
>> deteck from header to one or more tails.
>>
> GIM>> Great catch, thank you. Will fix in the next version.
>
>> >2.Section 1, 3rd paragraph says that active-tail is for further study.
>> So when a tail detects a failure, how will the head be notified?  If the
>> head does not have to be notified, what action is taken?
>>
>> [hfw] Ok. Actually, we are considering the active-tails solution. It
>>  will be added in the next version.
>>
> GIM>> Our plan is to use BFD for Multipoint Network with Active Tail
> specfication as the base for this mode. Since tails in p2mp BFD are in the
> Demand mode the head only can query all tail and/or the particular tail
> using the Poll sequence (referred as multicast and unicast Poll). Depending
> on the type of the failure, the head may recieve or not the BFD control
> message with Final flag set. Absence of the response in combination with
> the content of the Diag field must be used to draw the conclusion on
> liveleness of the path from the head to the particular tail. From here the
> head may use BIER Ping to localize the defect and switch to using the
> alternative path through the BIER domain by using different transient BFRs.
>
>>
>> Regards
>>
>> Fangwei.
>> *发件人:*ReshadRahman(rrahman) <rrahman@cisco.com>
>> *收件人:*draft-hu-bier-bfd@ietf.org <draft-hu-bier-bfd@ietf.org>rg>;
>> *抄送人:*bier@ietf.org <bier@ietf.org>;bfd@ietf.org <bfd@ietf.org>rg>;
>> *日 期 :*2018年11月08日 11:56
>> *主 题 :**Feedback on draft-hu-bier-bfd-02*
>>
>> Hi,
>>
>>
>>
>> I just took a quick look at the draft:
>>
>>    1.
>>
>>    Section 1, 2nd paragraph mentions “…detect unicast failures..”, I
>>    believe this  should be unidirectional?
>>    2.
>>
>>    Section 1, 3rd paragraph says that active-tail is for further study.
>>    So when a tail detects a failure, how will the head be notified?  If the
>>    head does not have to be notified, what action is taken?
>>
>>
>>
>> Regards,
>>
>> Reshad.
>>
>>
>>