Re: [Teas] Mirja Kühlewind's Discuss on draft-ietf-teas-rsvp-te-scaling-rec-06: (with DISCUSS and COMMENT)
Vishnu Pavan Beeram <vishnupavan@gmail.com> Tue, 13 February 2018 18:13 UTC
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From: Vishnu Pavan Beeram <vishnupavan@gmail.com>
Date: Tue, 13 Feb 2018 13:13:20 -0500
Message-ID: <CA+YzgTsY2NppQeWCLh9pTChK4n-GZxLgML30=feR8XVnLSN=-A@mail.gmail.com>
To: "Mirja Kuehlewind (IETF)" <ietf@kuehlewind.net>
Cc: Lou Berger <lberger@labn.net>, TEAS WG Chairs <teas-chairs@ietf.org>, The IESG <iesg@ietf.org>, "teas@ietf.org" <teas@ietf.org>, draft-ietf-teas-rsvp-te-scaling-rec@ietf.org
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Subject: Re: [Teas] Mirja Kühlewind's Discuss on draft-ietf-teas-rsvp-te-scaling-rec-06: (with DISCUSS and COMMENT)
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Mirja, Hi! Thanks for the response! It doesn't seem like we can make progress here if I keep recycling the same set of responses. I seem to have exhausted the "this is normal RSVP soft- state signaling behavior" line of argument :) I don't want to spend too much time arguing about a subtlety that (probably) only folks who have implemented RSVP-TE understand. So, let me try a different take on this. How about the following changes to the document? ** - Remove Section 2.3 (this takes out the contentious text) - Make the following change in Section 3 OLD: o MUST make the default value of the configurable refresh interval be a large value (10s of minutes). A default value of 20 minutes is RECOMMENDED by this document. NEW: o MUST make the default value of the configurable refresh interval (R) be a large value (10s of minutes). A default value of 20 minutes is RECOMMENDED by this document. o MUST use a separate refresh interval for refreshing state associated with unacknowledged Path/Resv messages (uR). A default value of 30 seconds is RECOMMENDED by this document. - Make the following change in Appendix A. OLD: (d) Periodic Retransmission Interval for unacknowledged Path/Resv messages (uR) - 30 seconds (Section 2.3). If the Retry-Limit (Rl) is 7, then it takes 31.5 seconds for the 7 rapid retransmit steps to max out (The last delay from message 6 to message 7 is 16 seconds). After the 7 rapid retransmit steps are maxed out, the router starts periodic retransmission on a slower timer. This document recommends the use of the traditional default refresh interval value of 30 seconds for this periodic retransmission interval. NEW: (d) Refresh interval for refreshing state associated with unacknowledged Path/Resv messages (uR)- 30 seconds (Section 3). The recommended refresh interval (R) value of 20 minutes (for an implementation supporting RI-RSVP) can not be used for refreshing state associated with unacknowledged Path/Resv messages. This document recommends the use of the traditional default refresh interval value of 30 seconds for uR. *** Let me know if the above changes address your concerns. Regards, -Pavan On Tue, Feb 13, 2018 at 9:22 AM, Mirja Kuehlewind (IETF) < ietf@kuehlewind.net> wrote: > Hi Pavan, > > I believe you that there may be implementation that transmit indefinitely, > however, that is not how I read RFC2961: > > " The staged retransmission will continue > until either an appropriate MESSAGE_ID_ACK object is received, or the > rapid retry limit, Rl, has been reached.“ > > or > > „The sending node will retransmit the message until a message > acknowledgment is received or the message has been transmitted a > maximum number of times.“ > > For me these sentences say that one should not retransmit anymore after > the max number is reached. If this is implemented differently, that is a > not safe behavior and need to be clarified. There must be a termination > condition. It is not safe for the stability of the Internet to retransmit > packets indefinitely. Packet loss can have may reason but continuous packet > loss is a clear sign of congestion that one can not be ignored. > > Mirja > > > > > Am 12.01.2018 um 14:15 schrieb Vishnu Pavan Beeram < > vishnupavan@gmail.com>: > > > > Mirja, Hi! > > > > I thought the following response (sent on Oct 5th 2017) addressed this > concern. > > > > ** Copying text from an earlier email ** > > There is nothing new about Path and Resv messages getting transmitted > indefinitely (this is normal soft-state signaling behavior). All that is > being discussed in this section is how these transmissions get paced after > the rapid retry limit is reached. The slower timer transmission will go on > until either an ack is received (at which point the regular "refresh > interval" comes into play) or the corresponding LSP instance state is torn > down. > > ** > > > > Please let me know if this still doesn't address the concern. We can set > up a call and walk through the base RSVP specs. > > > > Regards, > > -Pavan > > > > On Fri, Jan 12, 2018 at 7:12 AM, Mirja Kuehlewind (IETF) < > ietf@kuehlewind.net> wrote: > > Hi Vishnu, hi all, > > > > sorry but I lost a little bit track of this and looking at this now the > clarification provided below do not seem to address my concern. My concern > is that for messages (that a MESSAGE_ID object with the ACK_Desired flag > set), these messages would retransmit forever (even though only every 30s) > and there is not stop criteria to finally give up (and report an error). > > > > Mirja > > > > > > > Am 22.12.2017 um 08:44 schrieb Vishnu Pavan Beeram < > vishnupavan@gmail.com>: > > > > > > Mirja, Hi! > > > > > > Please see if the responses above address your concerns. Please let us > know if there are any issues with progressing this document. > > > > > > Regards, > > > -Pavan > > > > > > On Mon, Nov 13, 2017 at 4:21 AM, Lou Berger <lberger@labn.net> wrote: > > > Hi, > > > Please see below. > > > > > > On 11/13/2017 5:57 AM, Vishnu Pavan Beeram wrote: > > > Mirja, Hi! > > > > > > Apologize for the delayed reply. > > > Please see inline for responses (prefixed VPB). > > > > > > Regards, > > > -Pavan > > > > > > On Mon, Oct 16, 2017 at 6:25 AM, Mirja Kuehlewind (IETF) < > ietf@kuehlewind.net <mailto:ietf@kuehlewind.net>> wrote: > > > > > > Hi Vishnu, > > > > > > I don’t think what you proposed is a clarification at all. RF2961 > > > clearly reads to me that you should not retry any more after the > > > Rapid retry limit has been reached: > > > > > > > > > "Rl is the maximum number of times a message will be > > > transmitted without being acknowledged.“ > > > > > > > > > Please not that this section applies to "a message containing a > MESSAGE_ID object with the ACK_Desired flag set" and > > > > > > The ACK_Desired flag will typically be set only in trigger messages. > > > > > > This means that these procedure does not apply to normal RSVP refresh > processing and that normal RFC2205 defined Refresh Processing or Summary > Refresh processing continues. > > > > > > > > > [VPB] Yes. As per RFC2961, the retry limit (Rl) is the maximum number > of times a message will be transmitted without being acknowledged. But this > just governs the number of times you retransmit the message during the > "rapid retransmission phase". > > > > > > RFC2961 is silent about what happens after the "rapid retransmission > phase" is complete and this is the clarification that is being provided > here in the <scaling-rec> draft. > > > > > > The draft is silent in general about anything that is *not* modified > by the draft. I think having the informative statement is appropriate. > > > > > > Note that the associated RSVP Path/Resv state doesn't get cleaned up > after the "rapid retransmission" phase is complete. So at each subsequent > refresh-interval, the unacked Path/Resv message will be sent out again > (note that if there is no change in the state, the same MESSAGE_ID would > get used). This behavior has always existed in RSVP-TE implementations -- > so it is incorrect to deduce from the "RFC 2961" text above that the > retransmission of the unacked Path/Resv will never happen after the "Rl" is > reached. > > > > > > > > > Agreed. > > > Lou > > > > > > > > > Also RFC2961 suggests an initial Rf of 500ms with 7 retries and and > > > delta of 2, that means you will see the following retries: > > > > > > 1. after 500ms > > > 2. after 1000ms > > > 3. after 2000ms > > > 4. after 4000ms > > > 5. after 8000ms > > > 6. after 16000ms > > > 7. after 32000ms > > > > > > and then give up. While you suggests to send all 300ms section > > > afterwards forever. That is not acceptable and can lead to > congestion. > > > > > > > > > No, that is not what is being suggested. > > > RFC2961 suggests an Rf of 500ms with 3 retries and a delta of 2. So > the rapid retransmissions would be: > > > 1. after 500ms > > > 2. after 1000ms > > > 3. after 2000ms. > > > > > > With the proposal in the <scaling-rec> draft, you would try 7 times > and then stop the "rapid retransmission phase". So, what that means is that > the rapid retransmission phase lasts 31.5 seconds (first retry is after > 500ms and the seventh retry is after 32000ms). After this "rapid > retransmission phase" is complete, you keep sending the message out every > 30000ms (30seconds is not 300ms) until an acknowledgement is received. > > > > > > Hope this helps. > > > > > > > > > > > > Mirja > > > > > > > > > > > > > > > > Am 05.10.2017 um 22:27 schrieb Vishnu Pavan Beeram > > > <vishnupavan@gmail.com <mailto:vishnupavan@gmail.com>>: > > > > > > > > > > > Mirja, Hi! > > > > > > > > This was discussed in my response to Elwyn. I apologize for not > > > responding directly. > > > > > > > > RFC2961 doesn't discuss what to do with the retransmissions > after > > > the retry limit is reached. It doesn't discuss how retransmissions > > > need to be paced after the rapid retries are stopped. Section 2.3 > > > (ver 7) of the current draft clarifies this and proposes the use of > > > a "not so rapid (30secs)" retransmission interval. > > > > > > > > There were a couple of questions from this section that you > > > wanted to get discussed: > > > > ---- > > > > (1) Why is there no termination criteria specified? > > > > There is nothing new about Path and Resv messages getting > > > transmitted indefinitely (this is normal soft-state signaling > > > behavior). All that is being discussed in this section is how these > > > transmissions get paced after the rapid retry limit is reached. The > > > slower timer transmission will go on until either an ack is > received > > > (at which point the regular "refresh interval" comes into play) or > > > the corresponding LSP instance state is torn down. > > > > > > > > ---- > > > > (2) Why couldn't the regular refresh interval be used for these > > > un-acked retransmissions? > > > > The primary goal of the retransmission is to eke out an > > > acknowledgement from the neighbor as quickly as you can. You can > use > > > the same value as the the regular refresh interval provided it is > > > small enough (like in the case of the conventional refresh interval > > > of 30 secs) . However, we are recommending the use of a "large > > > refresh interval" (20 mins) in the RI-RSVP technique -- we can't > > > wait that long for retrying the transmission of an unacked message. > > > > > > > > Consider a rudimentary state machine with the following states > > > (assuming the defaults suggested in the Appendix of the draft): > > > > - first retransmit (exponential back off) > > > > - second retransmit (exponential back off) > > > > ... > > > > - seventh retransmit (exponential back off) > > > > - 30s retransmission > > > > - 20m refresh (regular refresh timer) > > > > > > > > At any point when the Ack is received, you transition to the 20m > > > refresh state. > > > > > > > > --- > > > > > > > > Do these two responses adequately answer your questions? > > > > > > > > Regards, > > > > -Pavan > > > > > > > > On Thu, Oct 5, 2017 at 7:57 AM, Mirja Kuehlewind (IETF) > > > <ietf@kuehlewind.net <mailto:ietf@kuehlewind.net>> wrote: > > > > Hi Pavan, > > > > > > > > I don’t see any changes in the new version that addresses may > > > actual discuss on section 2.1.3 (now section 2.3). Can you please > > > clarify? > > > > > > > > Thanks, > > > > Mirja > > > > > > > > > > > > > Am 28.09.2017 um 05:45 schrieb Vishnu Pavan Beeram > > > <vishnupavan@gmail.com <mailto:vishnupavan@gmail.com>>: > > > > > > > > > > Mirja, Hi! > > > > > > > > > > Thanks for the review. We just posted a new revision (-07) to > > > address the Gen-Art review comments. Please go through the new > diffs > > > (https://www.ietf.org/rfcdiff?url2=draft-ietf-teas-rsvp-te- > scaling-rec-07 > > > <https://www.ietf.org/rfcdiff?url2=draft-ietf-teas-rsvp-te- > scaling-rec-07>) > > > and let us know if additional changes are required. > > > > > > > > > > Also, please go through the responses provided to the other > > > review comments and let us know if there are still any unanswered > > > questions. > > > > > > > > > > Regards, > > > > > -Pavan > > > > > > > > > > > > > > > > > > > > On Tue, Sep 26, 2017 at 2:01 PM, Mirja Kühlewind > > > <ietf@kuehlewind.net <mailto:ietf@kuehlewind.net>> wrote: > > > > > Mirja Kühlewind has entered the following ballot position for > > > > > draft-ietf-teas-rsvp-te-scaling-rec-06: Discuss > > > > > > > > > > When responding, please keep the subject line intact and reply > > > to all > > > > > email addresses included in the To and CC lines. (Feel free to > > > cut this > > > > > introductory paragraph, however.) > > > > > > > > > > > > > > > Please refer to > > > https://www.ietf.org/iesg/statement/discuss-criteria.html > > > <https://www.ietf.org/iesg/statement/discuss-criteria.html> > > > > > for more information about IESG DISCUSS and COMMENT positions. > > > > > > > > > > > > > > > The document, along with other ballot positions, can be found > here: > > > > > > > > https://datatracker.ietf.org/doc/draft-ietf-teas-rsvp-te- > scaling-rec/ <https://datatracker.ietf.org/doc/draft-ietf-teas-rsvp-te- > scaling-rec/> > > > > > > > > > > > > > > > > > > > > > > > > > > ------------------------------------------------------------ > ---------- > > > > > DISCUSS: > > > > > > > > ------------------------------------------------------------ > ---------- > > > > > > > > > > I'm uncertain what section 2.1.3. actually recommends. My > > > understanding is that > > > > > it is recommend to still send retransmit some message even if > > > the Rl was > > > > > reached and to that every 30s basically forever. First of all > I > > > think this > > > > > still needs a termination criteria when to stop to try to > > > retransmit finally. > > > > > And the I don't understand why this is needed, instead of e.g. > > > just using a > > > > > larger Rl value? Can you please clarify! > > > > > > > > > > > > > > > > > > ------------------------------------------------------------ > ---------- > > > > > COMMENT: > > > > > > > > ------------------------------------------------------------ > ---------- > > > > > > > > > > I fully agree with the gan-art review (Thanks Elwyn!) and > > > Alvaro, that this > > > > > reads from time to time like a BCP but is actually a extension > > > specification. I > > > > > would strongly recommend to apply the changes proposed by the > > > gen-art review, > > > > > and there is also a very detailed list of nits/edits that > > > should probably be > > > > > applied. Please have a look at that! > > > > > > > > > > > > > > > _______________________________________________ > > > > > Teas mailing list > > > > > Teas@ietf.org <mailto:Teas@ietf.org> > > > > > https://www.ietf.org/mailman/listinfo/teas > > > <https://www.ietf.org/mailman/listinfo/teas> > > > > > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > Teas mailing list > > > Teas@ietf.org > > > https://www.ietf.org/mailman/listinfo/teas > > > > > > > > > > > > _______________________________________________ > Teas mailing list > Teas@ietf.org > https://www.ietf.org/mailman/listinfo/teas >
- [Teas] Mirja Kühlewind's Discuss on draft-ietf-te… Mirja Kühlewind
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Vishnu Pavan Beeram
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Mirja Kuehlewind (IETF)
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Vishnu Pavan Beeram
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Mirja Kuehlewind (IETF)
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Vishnu Pavan Beeram
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Lou Berger
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Vishnu Pavan Beeram
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Mirja Kuehlewind (IETF)
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Lou Berger
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Vishnu Pavan Beeram
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Mirja Kuehlewind (IETF)
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Vishnu Pavan Beeram
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Mirja Kuehlewind (IETF)
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Vishnu Pavan Beeram
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Mirja Kuehlewind (IETF)
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Vishnu Pavan Beeram
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Mirja Kuehlewind (IETF)
- Re: [Teas] Mirja Kühlewind's Discuss on draft-iet… Vishnu Pavan Beeram