Re: [manet-dlep-rg] notes DLEP meeting @ IETF88

Teco Boot <teco@inf-net.nl> Mon, 11 November 2013 21:39 UTC

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From: Teco Boot <teco@inf-net.nl>
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Date: Mon, 11 Nov 2013 22:39:26 +0100
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References: <72FB622921C13746AD6349E70A8D9F307D9192F7@EXC-MBX03.tsn.tno.nl> <CAK=bVC85XAXR3Zkwq+JwELF-dvgrKwbowWCvwvnjeVn7VStnbw@mail.gmail.com> <72FB622921C13746AD6349E70A8D9F307D9193CD@EXC-MBX03.tsn.tno.nl> <5A8A5085482DA84995F4E70F5093AB50268E6C@XCH-BLV-503.nw.nos.boeing.com> <B2BA430A-F4E6-4DED-A7BB-7282A22802B7@inf-net.nl> <5A8A5085482DA84995F4E70F5093AB50269139@XCH-BLV-503.nw.nos.boeing.com> <DAAF2F4E-8918-4708-8D68-4792A919541B@inf-net.nl> <5A8A5085482DA84995F4E70F5093AB502691C9@XCH-BLV-503.nw.nos.boeing.com> <EBD19831-B87C-4F37-B028-E00687B59FE1@inf-net.nl> <5A8A5085482DA84995F4E70F5093AB5026926A@XCH-BLV-503.nw.nos.boeing.com>
To: "Duke, Martin" <Martin.Duke@boeing.com>
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Subject: Re: [manet-dlep-rg] notes DLEP meeting @ IETF88
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Let's come back to this topic after we completed TCP connection and DLEP session management. Probably the issue is solved by then. 

Please comment on the TCP connection setup and maintenance. Below the proposal, adjusted after comments from Stan and Henning.

  Router                    Modem   Message Description
  ====================================================================

  <-------Peer Discovery---------   Modem initiates discovery
                                    with server TCP port
  ...
  <-------Peer Discovery---------   Repeats discovery forever
  ...

  ------------TCP SYN----------->   Router initiates TCP connection to TCP server 
                                    port from Peer Discovery
  <---------TCP SYN ACK----------   Modem part of TCP connection set up
  ------------TCP ACK----------->   Router finishes TCP connection set up

  -----------Peer Offer--------->   Router starts DLEP session with Offer
  <--------Peer Offer ACK--------   Modem joins in DLEP session with Offer Ack
  ---------Peer Offer ACK------->   Router completes DLEP session with Offer Ack

  <=============================>   DLEP session is established

  <--------Peer Heartbeat--------   Heartbeats when no other messages
  ---------Peer Heartbeat------->     between Router and Modem

  <---------Neighbor Up ---------   Modem sends Neighbor Up with metrics
                                    No DLEP Ack required

  <-------Neighbor Update--------   Modem Neighbor metrics update
  ...
  <-------Neighbor Update--------
  ...
  <--------Neighbor Down---------   Modem sends Neighbor Down

  When somethings goes wrong or down state is scheduled, DLEP session 
  terminates with TCP connection mechanism. Before, a Peer Error MAY
  be send.

  <----------Peer Error----------   Optional Modem error report
  <-------TCP RESET or FIN-------   Modem terminates session
        completed following 
           TCP procedure
  or
  -----------Peer Error--------->   Optional Router error report
  --------TCP RESET or FIN------>   Router terminates session
        completed following 
           TCP procedure

Teco

Op 11 nov. 2013, om 19:48 heeft Duke, Martin <Martin.Duke@boeing.com> het volgende geschreven:

> We must be talking past each other. In Section 11 of DLEP-04:
> 
> A Peer Discovery Message received from a modem that is
>   already in session MUST be processed as if a Peer Termination Message
>   had been received. A router implementation MAY then process the
>   received Peer Discovery Message.
> 
> The plain language interpretation of this is that a modem that continues to send out Peer Discovery messages to find new peers will trigger resets of existing sessions.
> 
> Perhaps the root problem is that we haven't really done a scrub for the implications of using TCP on all of the reliability mechanisms from previous drafts. I get confused on whether or not we're precluding UDP implementations, but maybe the right answer is to simply delete this provision.
> 
> -----Original Message-----
> From: Teco Boot [mailto:teco@inf-net.nl]
> Sent: Monday, November 11, 2013 10:31 AM
> To: Duke, Martin
> Cc: manet-dlep-rg@ietf.org
> Subject: Re: notes DLEP meeting @ IETF88
> 
> I might have missed some context here, discussed during post-meeting meeting.
> 
> Do you think there is a need for terminating the TCP connection, other than what TCP can provide? Maybe you had something in mind with heartbeat turned off and blocked TCP port. I prefer a non-blocking implementation. For a crashed DLEP agent, I can think of a Peer Order with Reset TLV, where router resets the modem. Would be similar to AT!RESET.
> 
> Teco
> 
> 
> Op 11 nov. 2013, om 17:33 heeft Duke, Martin <Martin.Duke@boeing.com> het volgende geschreven:
> 
>> Teco,
>> 
>> Although I follow that you want multiple peer sessions per modem, I'm having trouble parsing what your prescription is to address the peer session teardown problem I pointed out.
>> 
>> Martin
>> 
>> -----Original Message-----
>> From: Teco Boot [mailto:teco@inf-net.nl]
>> Sent: Monday, November 11, 2013 7:48 AM
>> To: Duke, Martin
>> Cc: manet-dlep-rg@ietf.org
>> Subject: Re: notes DLEP meeting @ IETF88
>> 
>> I think we keep Peer Discovery message generation and DLEP session maintenance separate. This keeps state machines less complex, less code, less bugs, increased functionality.
>> 
>> Having multiple DLEP session to same modem is related. If we support it, sending Peer Discovery messages shall not be stopped after first session.
>> 
>> Reason why I need multiple sessions: about half of modems I have to support have multiple ethernet ports. They serve multiple unrelated networks, there is no single connected router. Some modems are 6 digit $, we have to share these expensive assets. And they fully support it;).
>> 
>> Teco
>> 
>> 
>> Op 11 nov. 2013, om 16:30 heeft Duke, Martin <Martin.Duke@boeing.com> het volgende geschreven:
>> 
>>> Teco,
>>> 
>>> Yes, this point was at the very end. The current spec says that if the router receives a Peer Discovery message it must terminate any existing session with that modem. Clearly this is not acceptable behavior if the modem is continuing to multicast Peer Discovery messages when a peer session exists.
>>> 
>>> There are other ways to solve this problem, but the reply I got back was that there was no reason to keep seeking routers once a peer session exists. If there's disagreement on this point I'm happy  to back off the assertion that it's settled.
>>> 
>>> Martin
>>> 
>>> -----Original Message-----
>>> From: Teco Boot [mailto:teco@inf-net.nl]
>>> Sent: Friday, November 08, 2013 10:59 PM
>>> To: Duke, Martin
>>> Cc: DLEP Research Group (manet-dlep-rg@ietf.org)
>>> Subject: Re: notes DLEP meeting @ IETF88
>>> 
>>> Good summary, thanks. Let's only post the summary to the MANET ML.
>>> Having minutes archived on DLEP-RG ML would be fine, I think.
>>> 
>>> On 7: It was not discussed during our meeting, at least not were I was present. And I don't think this is a good idea. It is not needed and blocks more advanced usage of DLEP. Let's not have a restriction in that a router or modem has only a single DLEP peer.
>>> 
>>> Teco
>>> 
>>> Op 8 nov. 2013, om 21:40 heeft Duke, Martin <Martin.Duke@boeing.com> het volgende geschreven:
>>> 
>>>> Thanks Ron. That matches the notes I have. I might also add this summary of what I think we agreed on in terms of changing/clarifying the spec, which perhaps is more interesting than the play-by-play:
>>>> 
>>>> 1. There are no metric TLVs it is MANDATORY for the Router to process.
>>>> 2. The modem MUST report MDRT, MDRR, CDRT, and CDRR in the Peer Discovery message, and make a best effort to accurately report these metrics subsequently.
>>>> 3. The modem and router MUST include DLEP version in Peer Discovery and Peer Offer messages.
>>>> 4. The modem MUST include a Heartbeat Interval/Threshold TLV in its Peer Discovery messages. It is STRONGLY RECOMMENDED that the Interval be a nonzero value.
>>>> 5. The modem MUST include all metric TLVs it reports in the Peer Discovery Message to allow the router to initialize its session control block.
>>>> 6. The Router MUST NOT include metric TLVs in a Link Characteristics Request message that were not in the session's Peer Discovery message.
>>>> 7. The modem MUST NOT send Peer Discovery messages if it has an existing Peer Session.
>>>> 8. Both router and modem MUST send a Heartbeat Message to the peer if it has sent no DLEP message in an interval equivalent to the Heartbeat Interval value in the Peer Discovery Message. It MAY send a Heartbeat Message in every instance of the interval regardless of any other DLEP traffic.
>>>> 9. Both router and modem MUST reset their Heartbeat timer when any DLEP message arrives from the peer.
>>>> 10. The Heartbeat Interval/Threshold TLV becomes a "Heartbeat Interval TLV." Any DLEP peer is free to set any threshold for terminating the peer session as long as it equals or exceeds two Heartbeat Intervals, unless the Heartbeat Interval is zero.
>>>> 11. We will combine Expected Forwarding Time and Latency TLVs into a single, well-defined TLV.
>>>> 12. Delete the Resources TLVs.
>>>> 13. Keep the RLQ TLV, but Rick and Stan will formulate a stricter definition. There will be no other link quality TLVs (e.g. BER, packet delivery rate, SINR, etc) in the next draft.
>>>> 14. Stan to add clarifying language on how multicast neighbors work, in line with what he said at the meeting.
>>>> 
>>>> As Ron said, the form of the Credits TLVs are unresolved at this moment.
>>>> 
>>>> -----Original Message-----
>>>> From: Velt, R. (Ronald) in 't [mailto:Ronald.intVelt@tno.nl]
>>>> Sent: Thursday, November 07, 2013 5:58 PM
>>>> To: Ulrich Herberg
>>>> Cc: john.dowdell@cassidian.com; john.dowdell486@gmail.com;
>>>> Rick.Taylor@cassidian.com; Duke, Martin; Teco Boot
>>>> (teco@inf-net.nl); sratliff@cisco.com; Henning Rogge
>>>> (hrogge@googlemail.com); jpmacker@gmail.com; bcheng@ll.mit.edu
>>>> Subject: RE: notes DLEP meeting @ IETF88
>>>> 
>>>> I leave that up to the DLEP veterans to decide. They may want to
>>>> "redact" these notes a bit ;-)
>>>> 
>>>> Ronald
>>>> 
>>>>> -----Original Message-----
>>>>> From: Ulrich Herberg [mailto:ulrich@herberg.name]
>>>>> Sent: vrijdag 8 november 2013 2:44
>>>>> To: Velt, R. (Ronald) in 't
>>>>> Cc: john.dowdell@cassidian.com; john.dowdell486@gmail.com;
>>>>> Rick.Taylor@cassidian.com; Martin.Duke@boeing.com; Teco Boot
>>>>> (teco@inf- net.nl); sratliff@cisco.com; Henning Rogge
>>>>> (hrogge@googlemail.com); jpmacker@gmail.com; bcheng@ll.mit.edu
>>>>> Subject: Re: notes DLEP meeting @ IETF88
>>>>> 
>>>>> Thanks. Do you want to send them out to the MANET mailing list?
>>>>> 
>>>>> On Thu, Nov 7, 2013 at 5:40 PM, Velt, R. (Ronald) in 't
>>>>> <Ronald.intVelt@tno.nl>
>>>>> wrote:
>>>>>> Hi,
>>>>>> 
>>>>>> Please find attached my *raw* notes of our meeting on Tuesday.
>>>>> Disclaimer: Neither completeness nor correctness are guaranteed.
>>>>>> 
>>>>>> Best regards,
>>>>>> Ronald in 't Velt
>>>>>> 
>>>>>> ----
>>>>>> TNO Technical Sciences
>>>>>> 
>>>>>> Network Technology dept.
>>>>>> ----
>>>>>> 
>>>>>> 
>>>>>> 
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>>>> This message may contain information that is not intended for you. If you are not the addressee or if this message was sent to you by mistake, you are requested to inform the sender and delete the message. TNO accepts no liability for the content of this e-mail, for the manner in which you use it and for damage of any kind resulting from the risks inherent to the electronic transmission of messages.
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>