Re: [PWE3] [Technical Errata Reported] RFC4385 (1743)

[Yaakov Stein <yaakov_s at rad.com>]

Stewart

I agree that your approach is more general.

I was taking a more down-to-earth approach recognizing that all
the existing TDM encaps require the SN, while all the others don't.

However, I would be quite happy with a 4385-bis explicitly 
calling out two cases - 1 for optional SN and one for mandatory.

Y(J)S

-----Original Message-----
From: Stewart Bryant [mailto:stbryant at cisco.com] 
Sent: Friday, March 27, 2009 08:56
To: Alexander Vainshtein
Cc: RFC Errata System; swallow at cisco.com; Yaakov Stein; lmartini at cisco.com; rdroms at cisco.com; danny at arbor.net; townsley at cisco.com; pwe3 at ietf.org
Subject: Re: [PWE3] [Technical Errata Reported] RFC4385 (1743)

I do not think that we should call up the TDM drafts, but to talk in 
terms of all PWs for which the s/n is mandatory. There may at some time 
be non TDM drafts that also use zero as a valid s/n.

Stewart

Alexander Vainshtein wrote:
> It may be worth noting that the ALL the TDM PW RFCs have been published AFTER 4385 (which is easy to see if you compare the RFC numbers; the first TDM PW RFC to go out was 4553).
>
> So while the reporter has a point, I do not see how the problem could have been avoided...
>
> My 2c.
>      Sasha
>
> ________________________________________
> From: pwe3-bounces at ietf.org [pwe3-bounces at ietf.org] On Behalf Of Andrew G. Malis [amalis at gmail.com]
> Sent: Thursday, March 26, 2009 10:33 PM
> To: RFC Errata System
> Cc: swallow at cisco.com; yaakov_s at rad.com; pwe3 at ietf.org; lmartini at cisco.com; rdroms at cisco.com; danny at arbor.net; townsley at cisco.com; stbryant at cisco.com
> Subject: Re: [PWE3] [Technical Errata Reported] RFC4385 (1743)
>
> This errata should also include RFC 4842 in the list of TDM PW RFCs.
>
> Thanks,
> Andy
>
> On Thu, Mar 26, 2009 at 1:23 PM, RFC Errata System
> <rfc-editor at rfc-editor.org> wrote:
>   
>> The following errata report has been submitted for RFC4385,
>> "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for Use over an MPLS PSN".
>>
>> --------------------------------------
>> You may review the report below and at:
>> http://www.rfc-editor.org/errata_search.php?rfc=4385&eid=1743
>>
>> --------------------------------------
>> Type: Technical
>> Reported by: Yaakov (J) Stein <yaakov_s at rad.com>
>>
>> Section: 4, 4.1, 4.2
>>
>> Original Text
>> -------------
>> The sequence number mechanism described here uses a circular unsigned
>> 16-bit number space that excludes the value zero.
>> ...
>> o The sequence number that follows 65535 (maximum unsigned 16-bit
>>  number) is one.
>> ...
>> o If the sequence number on the packet is zero, the sequence
>>  integrity of the packets cannot be determined.  In this case, the
>>  received packet is considered to be in order.
>>
>> Corrected Text
>> --------------
>> The sequence number mechanism for all PW types except the TDM PWs
>> SAToP [RFC4335], CESoPSN [RFC5086], and TDMoIP [RFC5087] use a
>> circular unsigned 16-bit number space that excludes the value zero.
>> The TDM PWs include the value zero.
>> ...
>> o For all non-TDM PWs the sequence number that follows 65535
>> (maximum unsigned 16-bit number) is one.
>> ...
>> o If the sequence number on a non-TDM-PW packet is zero, the sequence
>>  integrity of the packets cannot be determined.  In this case, the
>>  received packet is considered to be in order.
>>
>> Notes
>> -----
>> While the fact that the TDM PWs always require the sequence number and thus do not give a zero value special meaning was well-known and documented in the relevant RFCs. However, this was forgotten in this document and is causing confusion to implementers.
>>
>> Instructions:
>> -------------
>> This errata is currently posted as "Reported". If necessary, please
>> use "Reply All" to discuss whether it should be verified or
>> rejected. When a decision is reached, the verifying party (IESG)
>> can log in to change the status and edit the report, if necessary.
>>
>> --------------------------------------
>> RFC4385 (draft-ietf-pwe3-cw-06)
>> --------------------------------------
>> Title               : Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for Use over an MPLS PSN
>> Publication Date    : February 2006
>> Author(s)           : S. Bryant, G. Swallow, L. Martini, D. McPherson
>> Category            : PROPOSED STANDARD
>> Source              : Pseudo Wire Emulation Edge to Edge
>> Area                : Internet
>> Stream              : IETF
>> Verifying Party     : IESG
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>>
>>     
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