Subject: Re: [Idr] Fwd: I-D Action: draft-keyur-idr-enhanced-gr-00.txt

From: <[email-masked]>
Date: Fri, 1 Jul 2011 10:29:30 +0200

Hi Keyur,

Thanks for you reply.

Please see inline.  #Bruno

>> 5. Operation
>>
>> 1) "Once the acknowledgment from a
>>    peer is not received within the specified upper bound, and the
>>    maintained state is compromised, then the speaker MUST clear the "TX
>>    Routing State" in the GR Capability to be advertised to the peer in
>>    the next session restart."
>>
>> Is there a chance to be able to achieve a resync some time later within the
>> same BGP session? E.g. if latter on we receive an acknowledgement, is it
>> possible to start again sending a new version number & maintaining the
>> required state? If so IMHO it could useful to say so since current sentence
>> could be understood as prohibiting this ("MUST clear the "TX Routing State" in
>> the GR Capability to be advertised to the peer in the next session restart.")
>>
>
>#Keyur: If the maintained state is compromised (e.g wrt Withdrawals) then
>you want to re-announce complete BGP table.

#Bruno: I agree with you in the following use case "1":
T0: version 1 sent & acked
T1: v2 sent (ack not received)
T2: states upper bound reached
T3: OPEN, GR, "TX routing Sate" cleared

But would the following use case "2" be possible:
T0: version 1 sent & acked
T1: v2 sent (ack not received)
T2: states upper bound reached
T3: v2 ack received.
T4: version 3 sent & acked
T5: OPEN, GR, "TX routing Sate" _set_

?
i.e. during T2-T4 TX routing states are lost. Following T4, TX routing states are valid and hence in the GR capability "TX routing Sate" can be _set_

>> 2) " During the lifetime of an established session, if needed, a BGP
>>    speaker MAY use the UPDATE-VERSION message to request updates from
>>    the last update version that was previously acknowledged as long as
>>    the speaker has received the Enhanced GR Capability from its peer.
>>
>>    When a BGP speaker receives such a request, it SHALL try to send
>>    routing information from the last acknowledged update version that
>>    the speaker has recorded.  If the speaker is unable to do so for some
>>    reason (e.g., "slow peer"), then it SHOULD perform a route refresh
>>    using mechanism defined in [EH-RR] if possible.  Otherwise, the BGP
>>    speaker SHOULD reset the session."
>>
>> - I would propose to add the following example as reason for not being able to
>> send the routes "did not maintained required states")
>> - By "reset the session" do you mean sending a NOTIFICATION or initiating an
>> OPEN with GR enabled? (I understand the former, why not using/allowing the
>> latter?)
>
>#Keyur: Notifications are fine as well as long as you have them on GR
>(draft-keyupate-idr-bgp-gr-extension).

#Bruno:  Agreed.
Yet, although I support draft-keyupate-idr-bgp-gr-extension, in the context of this document, we can assume that GR is enabled on that BGP session. We can't for draft-keyupate-idr-bgp-gr-extension.

>In any case we can provide a bit more clarification in the next rev.

Thanks,

Regards,
Bruno

>Regards,
>Keyur
>>
>> Thanks
>> Regards,
>> Bruno
>>
>> ---------------
>> From: [email-masked] [mailto:[email-masked]] On Behalf Of Enke
>> Chen
>> Sent: Wednesday, June 29, 2011 6:26 PM
>> To: [email-masked]
>> Cc: Keyur Patel
>> Subject: [Idr] Fwd: I-D Action: draft-keyur-idr-enhanced-gr-00.txt
>>
>> FYI.  Will appreciate your comments.
>>
>> Regards,   -- Enke
>>
>> -------- Original Message --------
>> Subject:
>> I-D Action: draft-keyur-idr-enhanced-gr-00.txt
>> Date:
>> Wed, 29 Jun 2011 09:21:21 -0700
>> From:
>> [email-masked]
>> Reply-To:
>> [email-masked]
>> To:
>> [email-masked]
>>
>> A New Internet-Draft is available from the on-line Internet-Drafts
>> directories.
>>
>> Title           : Accelerated Routing Convergence for BGP Graceful Restart
>> Author(s)       : Keyur Patel
>>                           Enke Chen
>>                           Rex Fernando
>>                           John Scudder
>> Filename        : draft-keyur-idr-enhanced-gr-00.txt
>> Pages           : 9
>> Date            : 2011-06-29
>>
>>    In this document we specify extensions to BGP graceful restart in
>>    order to avoid unnecessary transmission of the routing information
>>    preserved across a session restart, thus accelerating the routing
>>    convergence.
>>
>>
>>
>> A URL for this Internet-Draft is:
>> http://www.ietf.org/internet-drafts/draft-keyur-idr-enhanced-gr-00.txt
>>
>> Internet-Drafts are also available by anonymous FTP at:
>> ftp://ftp.ietf.org/internet-drafts/
>>
>> This Internet-Draft can be retrieved at:
>> ftp://ftp.ietf.org/internet-drafts/draft-keyur-idr-enhanced-gr-00.txt
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