Subject: [tsvwg] [Errata Verified] RFC4960 (3788)

From: RFC Errata System <[email-masked]>
Date: Mon, 13 Jan 2014 02:08:26 -0800 (PST)

The following errata report has been verified for RFC4960,
"Stream Control Transmission Protocol". 

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You may review the report below and at:
http://www.rfc-editor.org/errata_search.php?rfc=4960&eid=3788

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Status: Verified
Type: Technical

Reported by: Karen Nielsen <[email-masked]>
Date Reported: 2013-11-06
Verified by: Martin Stiemerling (IESG)

Section: 8.1

Original Text
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   An endpoint shall keep a counter on the total number of consecutive
   retransmissions to its peer (this includes retransmissions to all the
   destination transport addresses of the peer if it is multi-homed),
   including unacknowledged HEARTBEAT chunks.  

Corrected Text
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An endpoint shall keep a counter on the total number of consecutive
retransmissions to its peer (this includes data retransmissions 
to all the destination transport addresses of the peer if it is 
multi-homed),including the number of unacknowledged HEARTBEAT 
chunks observed on the path which currently is used for data 
transfer. Unacknowledged HEARTBEAT chunks observed on paths 
different from the path currently used for data transfer shall 
not increment the association error counter, as this could lead 
to association closure even if the path which 
currently is used for data transfer is available (but idle). 

Notes
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RFC4960 Endpoint Failure detection mechanism is deficient in that 
HB failures on some failing paths may take the association down, even 
if other paths are working perfectly, but simply at the time no data 
or HBs are being sent on the working paths.

The situation occurs when the association is idle 
(no data is being transmitted) and the HBI settings on 
the failing paths are much more aggressive than the HBI 
set on the working paths. RFC6458 allows for specification 
of the HBI on a per destination address whereby
such in-homogeneous setting of the HBI can occur.

The solution proposed to the issue is to demand that
HB failures observed on paths different from the path 
currently used for data transfer do
not contribute to the association error counter. 
HB failures observed on the path currently used for 
data transfer, when this path is idle, 
 shall contribute to the association error counter. 
Thereby supporting Endpoint Failure detection when the
association is idle. When the association is transmitting data, 
the fate of the data transmissions and retransmissions 
will serve to instantiate Endpoint Failure detection.

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RFC4960 (draft-ietf-tsvwg-2960bis-05)
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Title               : Stream Control Transmission Protocol
Publication Date    : September 2007
Author(s)           : R. Stewart, Ed.
Category            : PROPOSED STANDARD
Source              : Transport Area Working Group
Area                : Transport
Stream              : IETF
Verifying Party     : IESG