Network Working Group R. Stewart
Internet-Draft Netflix, Inc.
Intended status: Standards Track M. Tuexen
Expires: January 3, 2016 Muenster Univ. of Appl. Sciences
K. Nielsen
Ericsson
July 2, 2015
RFC 4960 Errata and Issues
draft-tuexen-tsvwg-rfc4960-errata-00.txt
Abstract
This document is a compilation of issues found since the publication
of RFC4960 in September 2007 based on experience with implementing,
testing, and using SCTP along with the suggested fixes. This
document provides deltas to RFC4960 and is organized in a time based
way. The issues are listed in the order they were brought up.
Because some text is changed several times the last delta in the text
is the one which should be applied. In addition to the delta a
description of the problem and the details of the solution are also
provided.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 3, 2016.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Corrections to RFC 4960 . . . . . . . . . . . . . . . . . . . 3
3.1. Path Error Counter Threshold Handling . . . . . . . . . . 3
3.2. Upper Layer Protocol Shutdown Request Handling . . . . . 4
3.3. Registration of New Chunk Types . . . . . . . . . . . . . 5
3.4. Variable Parameters for INIT Chunks . . . . . . . . . . . 6
3.5. CRC32c Sample Code on 64-bit Platforms . . . . . . . . . 7
3.6. Endpoint Failure Detection . . . . . . . . . . . . . . . 8
3.7. Data Transmission Rules . . . . . . . . . . . . . . . . . 9
3.8. T1-Cookie Timer . . . . . . . . . . . . . . . . . . . . . 10
3.9. Miscellaneous Typos . . . . . . . . . . . . . . . . . . . 11
3.10. CRC32c Sample Code . . . . . . . . . . . . . . . . . . . 15
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
5. Security Considerations . . . . . . . . . . . . . . . . . . . 15
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.1. Normative References . . . . . . . . . . . . . . . . . . 16
7.2. Informative References . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
This document contains a compilation of all defects found up until
the publishing of this document for [RFC4960] specifying the Stream
Control Transmission Protocol (SCTP). These defects may be of an
editorial or technical nature. This document may be thought of as a
companion document to be used in the implementation of SCTP to
clarify errors in the original SCTP document.
This document provides a history of the changes that will be compiled
into a BIS document for [RFC4960]. It is structured similar to
[RFC4460].
Each error will be detailed within this document in the form of:
o The problem description,
o The text quoted from [RFC4960],
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o The replacement text that should be placed into an upcoming BIS
document,
o A description of the solution.
Note that when reading this document one must use care to assure that
a field or item is not updated further on within the document. Each
section should be applied in sequence to the original [RFC4960] since
this document is a historical record of the sequential changes that
have been found necessary at various inter-op events and through
discussion on the list.
2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Corrections to RFC 4960
3.1. Path Error Counter Threshold Handling
3.1.1. Description of the Problem
The handling of the 'Path.Max.Retrans' parameter is described in
Section 8.2 and Section 8.3 of [RFC4960] in an Inconsistent way.
Whereas Section 8.2 describes that a path is marked inactive when the
path error counter exceeds the threshold, Section 8.3 says the path
is marked inactive when the path error counter reaches the threshold.
This issue was reported as an Errata for [RFC4960] with Errata ID
1440.
3.1.2. Text Changes to the Document
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---------
Old text: (Section 8.3)
---------
When the value of this counter reaches the protocol parameter
'Path.Max.Retrans', the endpoint should mark the corresponding
destination address as inactive if it is not so marked, and may also
optionally report to the upper layer the change of reachability of
this destination address. After this, the endpoint should continue
HEARTBEAT on this destination address but should stop increasing the
counter.
---------
New text: (Section 8.3)
---------
When the value of this counter exceeds the protocol parameter
'Path.Max.Retrans', the endpoint should mark the corresponding
destination address as inactive if it is not so marked, and may also
optionally report to the upper layer the change of reachability of
this destination address. After this, the endpoint should continue
HEARTBEAT on this destination address but should stop increasing the
counter.
3.1.3. Solution Description
The intended state change should happen when the threshold is
exceeded.
3.2. Upper Layer Protocol Shutdown Request Handling
3.2.1. Description of the Problem
Section 9.2 of [RFC4960] describes the handling of received SHUTDOWN
chunks in the SHUTDOWN-RECEIVED state instead of the handling of
shutdown requests from its upper layer in this state.
This issue was reported as an Errata for [RFC4960] with Errata ID
1574.
3.2.2. Text Changes to the Document
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---------
Old text: (Section 9.2)
---------
Once an endpoint has reached the SHUTDOWN-RECEIVED state, it MUST NOT
send a SHUTDOWN in response to a ULP request, and should discard
subsequent SHUTDOWN chunks.
---------
New text: (Section 9.2)
---------
Once an endpoint has reached the SHUTDOWN-RECEIVED state, it MUST NOT
send a SHUTDOWN in response to a ULP request, and should discard
subsequent ULP shutdown requests.
3.2.3. Solution Description
The text never intended the SCTP endpoint to ignore SHUTDOWN chunks
from its peer. If it did the endpoints could never gracefully
terminate a associations in some cases.
3.3. Registration of New Chunk Types
3.3.1. Description of the Problem
Section 14.1 of [RFC4960] should deal with new chunk types, however,
the text refers to parameter types.
This issue was reported as an Errata for [RFC4960] with Errata ID
2592.
3.3.2. Text Changes to the Document
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---------
Old text: (Section 14.1)
---------
The assignment of new chunk parameter type codes is done through an
IETF Consensus action, as defined in [RFC2434]. Documentation of the
chunk parameter MUST contain the following information:
---------
New text: (Section 14.1)
---------
The assignment of new chunk type codes is done through an
IETF Consensus action, as defined in [RFC2434]. Documentation of the
chunk type MUST contain the following information:
3.3.3. Solution Description
Refer to chunk types as intended.
3.4. Variable Parameters for INIT Chunks
3.4.1. Description of the Problem
Newlines in wrong places break the layout of the table of variable
parameters for the INIT chunk in Section 3.3.2 of [RFC4960].
This issue was reported as an Errata for [RFC4960] with Errata ID
3291 and Errata ID 3804.
3.4.2. Text Changes to the Document
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---------
Old text: (Section 3.3.2)
---------
Variable Parameters Status Type Value
-------------------------------------------------------------
IPv4 Address (Note 1) Optional 5 IPv6 Address
(Note 1) Optional 6 Cookie Preservative
Optional 9 Reserved for ECN Capable (Note 2) Optional
32768 (0x8000) Host Name Address (Note 3) Optional
11 Supported Address Types (Note 4) Optional 12
---------
New text: (Section 3.3.2)
---------
Variable Parameters Status Type Value
-------------------------------------------------------------
IPv4 Address (Note 1) Optional 5
IPv6 Address (Note 1) Optional 6
Cookie Preservative Optional 9
Reserved for ECN Capable (Note 2) Optional 32768 (0x8000)
Host Name Address (Note 3) Optional 11
Supported Address Types (Note 4) Optional 12
3.4.3. Solution Description
Fix the formatting of the table.
3.5. CRC32c Sample Code on 64-bit Platforms
3.5.1. Description of the Problem
The sample code for computing the CRC32c provided in [RFC4960]
assumes that a variable of type unsigned long uses 32 bits. This is
not true on some 64-bit platforms (for example the ones using LP64).
This issue was reported as an Errata for [RFC4960] with Errata ID
3423.
3.5.2. Text Changes to the Document
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---------
Old text: (Appendix C)
---------
unsigned long
generate_crc32c(unsigned char *buffer, unsigned int length)
{
unsigned int i;
unsigned long crc32 = ~0L;
---------
New text: (Appendix C)
---------
unsigned long
generate_crc32c(unsigned char *buffer, unsigned int length)
{
unsigned int i;
unsigned long crc32 = 0xffffffffL;
3.5.3. Solution Description
Use 0xffffffffL instead of ~0L which gives the same value on
platforms using 32 bits or 64 bits for variables of type unsigned
long.
3.6. Endpoint Failure Detection
3.6.1. Description of the Problem
The handling of the association error counter defined in Section 8.1
of [RFC4960] can result in an association failure even if the path
used for data transmission is available, but idle.
This issue was reported as an Errata for [RFC4960] with Errata ID
3788.
3.6.2. Text Changes to the Document
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---------
Old text: (Section 8.1)
---------
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.
---------
New text: (Section 8.1)
---------
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).
3.6.3. Solution Description
A more refined handling for the association error counter is defined.
3.7. Data Transmission Rules
3.7.1. Description of the Problem
When integrating the changes to Section 6.1 A) of [RFC2960] as
described in Section 2.15.2 of [RFC4460] some text was duplicated and
became the final paragraph of Section 6.1 A) of [RFC4960].
This issue was reported as an Errata for [RFC4960] with Errata ID
4071.
3.7.2. Text Changes to the Document
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---------
Old text: (Section 6.1 A))
---------
The sender MUST also have an algorithm for sending new DATA chunks
to avoid silly window syndrome (SWS) as described in [RFC0813].
The algorithm can be similar to the one described in Section
4.2.3.4 of [RFC1122].
However, regardless of the value of rwnd (including if it is 0),
the data sender can always have one DATA chunk in flight to the
receiver if allowed by cwnd (see rule B below). This rule allows
the sender to probe for a change in rwnd that the sender missed
due to the SACK having been lost in transit from the data receiver
to the data sender.
---------
New text: (Section 6.1 A))
---------
The sender MUST also have an algorithm for sending new DATA chunks
to avoid silly window syndrome (SWS) as described in [RFC0813].
The algorithm can be similar to the one described in Section
4.2.3.4 of [RFC1122].
3.7.3. Solution Description
Last paragraph of Section 6.1 A) removed as intended in
Section 2.15.2 of [RFC4460].
3.8. T1-Cookie Timer
3.8.1. Description of the Problem
Figure 4 of [RFC4960] illustrates the SCTP association setup.
However, it incorrectly shows that the T1-init timer is used in the
COOKIE-ECHOED state whereas the T1-cookie timer should have been used
instead.
This issue was reported as an Errata for [RFC4960] with Errata ID
4400.
3.8.2. Text Changes to the Document
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---------
Old text: (Section 5.1.6, Figure 4)
---------
COOKIE ECHO [Cookie_Z] ------\
(Start T1-init timer) \
(Enter COOKIE-ECHOED state) \---> (build TCB enter ESTABLISHED
state)
/---- COOKIE-ACK
/
(Cancel T1-init timer, <-----/
Enter ESTABLISHED state)
---------
New text: (Section 5.1.6, Figure 4)
---------
COOKIE ECHO [Cookie_Z] ------\
(Start T1-cookie timer) \
(Enter COOKIE-ECHOED state) \---> (build TCB enter ESTABLISHED
state)
/---- COOKIE-ACK
/
(Cancel T1-cookie timer, <---/
Enter ESTABLISHED state)
3.8.3. Solution Description
Change the figure such that the T1-cookie timer is used instead of
the T1-init timer.
3.9. Miscellaneous Typos
3.9.1. Description of the Problem
While processing [RFC4960] some typos were not catched.
3.9.2. Text Changes to the Document
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---------
Old text: (Section 1.6)
---------
Transmission Sequence Numbers wrap around when they reach 2**32 - 1.
That is, the next TSN a DATA chunk MUST use after transmitting TSN =
2*32 - 1 is TSN = 0.
---------
New text: (Section 1.6)
---------
Transmission Sequence Numbers wrap around when they reach 2**32 - 1.
That is, the next TSN a DATA chunk MUST use after transmitting TSN =
2**32 - 1 is TSN = 0.
---------
Old text: (Section 3.3.10.9)
---------
No User Data: This error cause is returned to the originator of a
DATA chunk if a received DATA chunk has no user data.
---------
New text: (Section 3.3.10.9)
---------
No User Data: This error cause is returned to the originator of a
DATA chunk if a received DATA chunk has no user data.
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---------
Old text: (Section 6.7, Figure 9)
---------
Endpoint A Endpoint Z {App
sends 3 messages; strm 0} DATA [TSN=6,Strm=0,Seq=2] ----------
-----> (ack delayed) (Start T3-rtx timer)
DATA [TSN=7,Strm=0,Seq=3] --------> X (lost)
DATA [TSN=8,Strm=0,Seq=4] ---------------> (gap detected,
immediately send ack)
/----- SACK [TSN Ack=6,Block=1,
/ Start=2,End=2]
<-----/ (remove 6 from out-queue,
and mark 7 as "1" missing report)
---------
New text: (Section 6.7, Figure 9)
---------
Endpoint A Endpoint Z
{App sends 3 messages; strm 0}
DATA [TSN=6,Strm=0,Seq=2] ---------------> (ack delayed)
(Start T3-rtx timer)
DATA [TSN=7,Strm=0,Seq=3] --------> X (lost)
DATA [TSN=8,Strm=0,Seq=4] ---------------> (gap detected,
immediately send ack)
/----- SACK [TSN Ack=6,Block=1,
/ Strt=2,End=2]
<-----/
(remove 6 from out-queue,
and mark 7 as "1" missing report)
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---------
Old text: (Section 6.10)
---------
An endpoint bundles chunks by simply including multiple chunks in one
outbound SCTP packet. The total size of the resultant IP datagram,
including the SCTP packet and IP headers, MUST be less that or equal
to the current Path MTU.
---------
New text: (Section 6.10)
---------
An endpoint bundles chunks by simply including multiple chunks in one
outbound SCTP packet. The total size of the resultant IP datagram,
including the SCTP packet and IP headers, MUST be less that or equal
to the current Path MTU.
---------
Old text: (Section 6.10)
---------
o Receive Unacknowledged Message
Format: RECEIVE_UNACKED(data retrieval id, buffer address, buffer
size, [,stream id] [, stream sequence number] [,partial
flag] [,payload protocol-id])
---------
New text: (Section 6.10)
---------
O) Receive unacknowledged message
Format: RECEIVE_UNACKED(data retrieval id, buffer address, buffer size,
[,stream id] [, stream sequence number] [,partial flag]
[,payload protocol-id])
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---------
Old text: (Appendix C)
---------
ICMP2) An implementation MAY ignore all ICMPv6 messages where the
type field is not "Destination Unreachable", "Parameter
Problem",, or "Packet Too Big".
---------
New text: (Appendix C)
---------
ICMP2) An implementation MAY ignore all ICMPv6 messages where the
type field is not "Destination Unreachable", "Parameter
Problem", or "Packet Too Big".
3.9.3. Solution Description
Typos fixed.
3.10. CRC32c Sample Code
3.10.1. Description of the Problem
The CRC32c computation is described in Appendix B of [RFC4960].
However, the corresponding sample code and its explanation appears at
the end of Appendix C, which deals with ICMP handling.
3.10.2. Text Changes to the Document
Move the sample code related to CRC32c computation and its
explanation from the end of Appendix C to the end of Appendix B.
3.10.3. Solution Description
Text moved to the appropriate location.
4. IANA Considerations
This documents does not require any actions from IANA.
5. Security Considerations
This document does not add any security considerations to those given
in [RFC4960].
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6. Acknowledgments
The authors wish to thank Pontus Andersson, Eric W. Biederman, Jeff
Morriss, Tom Petch, and Julien Pourtet for their invaluable comments.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC
4960, September 2007.
7.2. Informative References
[RFC2960] Stewart, R., Xie, Q., Morneault, K., Sharp, C.,
Schwarzbauer, H., Taylor, T., Rytina, I., Kalla, M.,
Zhang, L., and V. Paxson, "Stream Control Transmission
Protocol", RFC 2960, October 2000.
[RFC4460] Stewart, R., Arias-Rodriguez, I., Poon, K., Caro, A., and
M. Tuexen, "Stream Control Transmission Protocol (SCTP)
Specification Errata and Issues", RFC 4460, April 2006.
Authors' Addresses
Randall R. Stewart
Netflix, Inc.
Chapin, SC 29036
United States
Email: randall@lakerest.net
Michael Tuexen
Muenster University of Applied Sciences
Stegerwaldstrasse 39
48565 Steinfurt
Germany
Email: tuexen@fh-muenster.de
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Karen E. E. Nielsen
Ericsson
Kistavaegen 25
Stockholm 164 80
Sweden
Email: karen.nielsen@tieto.com
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