IPv6 Performance and Diagnostic Metrics Destination Option
draft-elkins-6man-ipv6-pdm-dest-option-02
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|---|---|---|---|
| Authors | Nalini Elkins , William Jouris | ||
| Last updated | 2013-10-03 | ||
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draft-elkins-6man-ipv6-pdm-dest-option-02
INTERNET-DRAFT N. Elkins
Intended Status: Proposed Standard W. Jouris
Inside Products
Expires: April 2014 October 3, 2013
IPv6 Performance and Diagnostic Metrics Destination Option
draft-elkins-6man-ipv6-pdm-dest-option-02
Abstract
To diagnose performance and connectivity problems, metrics on real
(non-synthetic) transmission are critical for timely end-to-end
problem resolution. Such diagnostics may be real-time or after the
fact, but must not impact an operational production network. The base
metrics are: packet sequence number and packet timestamp. Metrics
derived from these will be described separately. This document solves
these problems with a new destination option, the Performance and
Diagnostic Metrics destination option (PDM).
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
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Copyright and License Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Performance and Diagnostic Metrics Destination Option . . . . . 4
2.1 Destination Options Header . . . . . . . . . . . . . . . . 4
2.2 Performance and Diagnostic Metrics Destination Option . . . 5
2.3 Implementation Considerations . . . . . . . . . . . . . . . 8
2.3.1 Dynamic Configuration Options . . . . . . . . . . . . . 8
2.3.2 Data Length Filtering . . . . . . . . . . . . . . . . . 9
2.3.3 5-tuple Aging . . . . . . . . . . . . . . . . . . . . . 9
2.4 Sample Implementation Flow . . . . . . . . . . . . . . . . 10
3.1 Step 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
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3.2 Step 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.3 Step 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.4 Step 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.5 Step 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3 Backward Compatibility . . . . . . . . . . . . . . . . . . . . 13
4 Security Considerations . . . . . . . . . . . . . . . . . . . . 13
5 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 13
6 References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.1 Normative References . . . . . . . . . . . . . . . . . . . . 13
7 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
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1 Introduction
To diagnose performance and connectivity problems, metrics on real
(non-synthetic) transmission are critical for timely end-to-end
problem resolution. Such diagnostics may be real-time or after the
fact, but must not impact an operational production network. The base
metrics are: packet sequence number and packet timestamp.
For background, please see draft-ackermann-tictoc-pdm-ntp-usage-00
[ACKPDM], draft-elkins-v6ops-ipv6-packet-sequence-needed-01 [ELKPSN],
draft-elkins-v6ops-ipv6-pdm-recommended-usage-01 [ELKUSE], draft-
elkins-v6ops-ipv6-end-to-end-rt-needed-01 [ELKRSP] and draft-elkins-
ippm-pdm-metrics-00 [ELKIPPM]. These drafts are companions to this
document.
As discussed in the above Internet Drafts, current methods are
inadequate for these purposes because they assume unreasonable access
to intermediate devices, are cost prohibitive, require infeasible
changes to a running production network, and / or do not provide
timely data. This document provides a solution for these problems.
As defined in RFC2460 [RFC2460], destination options are carried by
the IPv6 Destination Options extension header. Destination options
include optional information that need be examined only by the IPv6
node given as the destination address in the IPv6 header, not by
routers or other "middle boxes". This document specifies a new
destination option, the Performance and Diagnostic Metrics
destination option (PDM).
1.1 Terminology
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 RFC 2119 [RFC2119].
2 Performance and Diagnostic Metrics Destination Option
2.1 Destination Options Header
The IPv6 Destination Options Header is used to carry optional
information that need be examined only by a packet's destination
node(s). The Destination Options Header is identified by a Next
Header value of 60 in the immediately preceding header and is defined
in RFC2460 [RFC2460].
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2.2 Performance and Diagnostic Metrics Destination Option
The IPv6 Performance and Diagnostic Metrics Destination Option (PDM)
is an implementation of the Destination Options Header (Next Header
value = 60).
It is used to facilitate diagnostics by including a packet sequence
number and timestamp.
The PDM destination option is encoded in type-length-value (TLV)
format as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Option Length | PSN This Packet |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ TimeStamp This Packet (64-bit) +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PSN Last Packet | Reserved |
|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ TimeStamp Last Packet (64-bit) +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option Type
TBD = 0xXX (TBD) [To be assigned by IANA] [RFC2780]
Option Length
8-bit unsigned integer. Length of the option, in octets, excluding
the Option Type and Option Length fields. This field MUST be set to
22.
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Packet Sequence Number This Packet (PSNTP)
16-bit unsigned integer. This field will wrap. It is intended for
human use.
Initialized at a random number and monotonically incremented for
packet on the 5-tuple. The 5-tuple consists of the source and
destination IP addresses, the source and destination ports, and the
upper layer protocol (ex. TCP, ICMP, etc).
Operating systems MUST implement a separate packet sequence number
counter per 5-tuple. Operating systems MUST NOT implement a single
counter for all connections.
Note: This is consistent with the current implementation of the IPID
field in IPv4 for many, but not all, stacks.
TimeStamp This Packet (TSTP)
A 64-bit unsigned integer field containing a timestamp that this
packet was sent by the source node. The value indicates the number
of seconds since January 1, 1970, 00:00 UTC, by using a fixed point
format. In this format, the integer number of seconds is contained
in the first 32 bits of the field, and the remaining 32 bits resolve
to picoseconds.
This follows timestamp formats used in Network Time Protocol (NTP)
[RFC5905] and SEND [RFC3971]. A discussion of why NTP is used in
preference to Precision Time Protocol (PTP) is in draft-elkins-v6ops-
ipv6-end-to-end-rt-needed-01 [ELKRSP]. A discussion of how to
implement NTP for use with the PDM header is in draft-ackermann-
tictoc-pdm-ntp-usage-00 [ACKPDM].
Implementation note: This format is compatible with the usual
representation of time under UNIX, although the number of bits
available for the integer and fraction parts in different Unix
implementations vary.
Packet Sequence Number Last Received (PSNLR)
16-bit unsigned integer. This is the PSN of the packet last received
on the 5-tuple.
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TimeStamp Last Received (TSLR)
A 64-bit unsigned integer field containing a timestamp. This is the
timestamp of the packet last received on the 5-tuple.
The value indicates the number of seconds since January 1, 1970,
00:00 UTC, by using a fixed point format. In this format, the
integer number of seconds is contained in the first 32 bits of the
field, and the remaining 32 bits resolve to picoseconds.
Option Type
The two highest-order bits of the Option Type field are encoded to
indicate specific processing of the option; for the PDM destination
option, these two bits MUST be set to 00. This indicates the
following processing requirements:
00 - skip over this option and continue processing the header.
RFC2460 [RFC2460] defines other values for the Option Type field.
These MUST NOT be used in the PDM. The other values are as follows:
01 - discard the packet.
10 - discard the packet and, regardless of whether or not the
packet's Destination Address was a multicast address, send an ICMP
Parameter Problem, Code 2, message to the packet's Source Address,
pointing to the unrecognized Option Type.
11 - discard the packet and, only if the packet's Destination
Address was not a multicast address, send an ICMP Parameter Problem,
Code 2, message to the packet's Source Address, pointing to the
unrecognized Option Type.
In keeping with RFC2460 [RFC2460], the third-highest-order bit of the
Option Type specifies whether or not the Option Data of that option
can change en-route to the packet's final destination.
In the PDM, the value of the third-highest-order bit MUST be 0. The
possible values are as follows:
0 - Option Data does not change en-route
1 - Option Data may change en-route
The three high-order bits described above are to be treated as part
of the Option Type, not independent of the Option Type. That is, a
particular option is identified by a full 8-bit Option Type, not just
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the low-order 5 bits of an Option Type.
Header Placement
The PDM destination option MUST be placed as follows:
- Before the upper-layer header. That is, this is the last
extension header.
This follows the order defined in RFC2460 [RFC2460]
IPv6 header
Hop-by-Hop Options header
Destination Options header
Routing header
Fragment header
Authentication header
Encapsulating Security Payload header
Destination Options header
upper-layer header
For each IPv6 packet header, the PDM MUST NOT appear more than once.
However, an encapsulated packet MAY contain a separate PDM associated
with each encapsulated IPv6 header.
The inclusion of a PDM in a packet affects the receiving node's
processing of only this single packet. No state is created or
modified in the receiving node as a result of receiving a PDM in a
packet.
2.3 Implementation Considerations
The PDM destination options extension header SHOULD be turned on by
each stack on a host node.
2.3.1 Dynamic Configuration Options
If implemented, each operating system MUST have a default
configuration parameter, e.g. diag_header_sys_default_value=yes/no.
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The operating system MAY also have a dynamic configuration option to
change the configuration setting as needed.
If the PDM destination options extension header is used, then it MAY
be turned on for all packets flowing through the host, applied to an
upper-layer protocol (TCP, UDP, SCTP, etc), a local port, or IP
address only. These are at the discretion of the implementation.
The PDM MUST NOT be changed dynamically via packet flow as this may
create potential security violation or DoS attack by numerous packets
turning the header on and off.
As with all other destination options extension headers, the PDM is
for destination nodes only. As specified above, intermediate devices
MUST neither set nor modify this field.
2.3.2 Data Length Filtering
Different results for derived metrics, such as, server delay, will be
obtained if calculations are done including or excluding packets
which have a data length of 0 or 1. Some protocols, for example,
TCP, provide acknowledgements which have a length of 0. Keep-alive
packets have a data length of 0 or 1.
Operating systems may provide the user a choice of whether to include
or exclude packets with a zero or 1 byte data length.
2.3.3 5-tuple Aging
Within the operating system, metrics must be kept on a 5-tuple basis.
As will be discussed in section 2.4, these are:
PSNTP : Packet Sequence Number This Packet
TSTP : Timestamp This Packet
PSNLR : Packet Sequence Number Last Received
TSLR : Timestamp Last Received
PROTC : Protocol for Upper Layer (ex. TCP, UDP, ICMP, etc)
The question comes of when to stop keeping data or restarting the
numbering for a 5-tuple. For example, in the case of TCP, at some
point, the connection will terminate. Keeping data in control blocks
forever, will have unfortunate consequences for the operating system.
The choice of aging parameter is left up to the implementation.
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2.4 Sample Implementation Flow
Following is a sample simple flow with one packet sent from Host A
and one packet received by Host B. The calculations to derive
meaningful metrics for network diagnostics from these fields is
described in draft-elkins-ippm-pdm-metrics-00 [ELKIPPM].
Time synchronization is required between Host A and Host B.
Each packet, in addition to the PDM contains information on the
sender and receiver. This is the 5-tuple consisting of:
SADDR : IP address of the sender
SPORT : Port for sender
DADDR : IP address of the destination
DPORT : Port for destination
PROTC : Protocol for upper layer (ex. TCP, UDP, ICMP, etc.)
It should be understood that the packet identification information is
in each packet. We will not repeat that in each of the following
steps.
3.1 Step 1
Packet 1 is sent from Host A to Host B. The time for Host A is set
initially to 10:00AM.
The timestamp and packet sequence number are sent in the PDM.
The initial PSNTP from Host A starts at a random number. In this
case, 25. The sub-second portion of the timestamp has been omitted
for the sake of simplicity.
Packet 1
+----------+ +----------+
| | | |
| Host | ----------> | Host |
| A | | B |
| | | |
+----------+ +----------+
PDM Contents:
PSNTP : Packet Sequence Number This Packet: 25
TSTP : Timestamp This Packet: 10:00:00
PSNLR : Packet Sequence Number Last Received: -
TSLR : Timestamp Last Received: -
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3.2 Step 2
Packet 1 is received by Host B. The time for Host B was synchronized
with Host A. Both were set initially to 10:00AM.
The timestamp and PSN for the received packet are placed in the PSNLR
and TSLR fields. These are from the point of view of B. That is,
they indicate when the packet from A was received and which packet it
was.
The PDM is not sent at this point. It is only prepared. It will be
sent when the response to packet 1 is sent by Host B.
Packet 1 Received
+----------+ +----------+
| | | |
| Host | ----------> | Host |
| A | | B |
| | | |
+----------+ +----------+
PDM Contents:
PSNTP : Packet Sequence Number This Packet: -
TSTP : Timestamp This Packet: -
PSNLR : Packet Sequence Number Last Received: 25
TSLR : Timestamp Last Received: 10:00:03
3.3 Step 3
Packet 2 is sent from Host B to Host A. The initial PSNTP from Host
B starts at a random number. In this case, 12.
Packet 2
+----------+ +----------+
| | | |
| Host | <---------- | Host |
| A | | B |
| | | |
+----------+ +----------+
PDM Contents:
PSNTP : Packet Sequence Number This Packet: 12
TSTP : Timestamp This Packet: 10:00:07
PSNLR : Packet Sequence Number Last Received: 25
TSLR : Timestamp Last Received: 10:00:03
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3.4 Step 4
Packet 2 is received by Host A.
The timestamp and PSN for the received packet are placed in the PSNLR
and TSLR fields. These are from the point of view of A. That is,
they indicate when the packet from B was received and which packet it
was.
The PDM is not sent at this point. It is only prepared. It will be
sent when the NEXT packet to Host B is sent by Host A. If there is no
next packet for the 5-tuple, as may be the case for UDP, then this
value will be missing.
Packet 2 Received
+----------+ +----------+
| | | |
| Host | <---------- | Host |
| A | | B |
| | | |
+----------+ +----------+
PDM Contents:
PSNTP : Packet Sequence Number This Packet: -
TSTP : Timestamp This Packet: -
PSNLR : Packet Sequence Number Last Received: 12
TSLR : Timestamp Last Received: 10:00:10
3.5 Step 5
Packet 3 is sent from Host A to Host B.
Packet 3
+----------+ +----------+
| | | |
| Host | ----------> | Host |
| A | | B |
| | | |
+----------+ +----------+
PDM Contents:
PSNTP : Packet Sequence Number This Packet: 26
TSTP : Timestamp This Packet: 10:00:50
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PSNLR : Packet Sequence Number Last Received: 12
TSLR : Timestamp Last Received: 10:00:10
3 Backward Compatibility
The scheme proposed in this document is backward compatible with all
the currently defined IPv6 extension headers. According to RFC2460
[RFC2460], if the destination node does not recognize this option, it
should skip over this option and continue processing the header.
4 Security Considerations
The PDM MUST NOT be changed dynamically via packet flow as this
creates a possibility for potential security violations or DoS
attacks by numerous packets turning the header on and off.
5 IANA Considerations
An option type must be assigned by IANA for the Performance and
Diagnostic Metrics destination option.
6 References
6.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC2780] Bradner, S. and V. Paxson, "IANA Allocation Guidelines For
Values In the Internet Protocol and Related Headers",
BCP 37, RFC 2780, March 2000.
[RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
"SEcure Neighbor Discovery (SEND)", RFC 3971, March 2005.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010.
[ACKPDM] Ackermann, M., "draft-ackermann-tictoc-pdm-ntp-usage-00",
Internet Draft, September 2013.
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[ELKPSN] Elkins, N., "draft-elkins-v6ops-ipv6-packet-sequence-
needed-01", Internet Draft, September 2013.
[ELKRSP] Elkins, N., "draft-elkins-v6ops-ipv6-end-to-end-rt-needed-
01", Internet Draft, September 2013.
[ELKUSE] Elkins, N., "draft-elkins-v6ops-ipv6-pdm-recommended-usage-
01", Internet Draft, September 2013
[ELKIPPM] Elkins, N., "Draft-elkins-ippm-pdm-metrics-00", Internet
Draft, September 2013.
7 Acknowledgments
The authors would like to thank Mike Ackermann, Keven
Haining, Sigfrido Perdomo, David Boyes, Rick Troth and
Fred Baker for their comments.
Authors' Addresses
Nalini Elkins
Inside Products, Inc.
36A Upper Circle
Carmel Valley, CA 93924
United States
Phone: +1 831 659 8360
Email: nalini.elkins@insidethestack.com
http://www.insidethestack.com
William Jouris
Inside Products, Inc.
36A Upper Circle
Carmel Valley, CA 93924
United States
Phone: +1 925 855 9512
Email: bill.jouris@insidethestack.com
http://www.insidethestack.com
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