Internet DRAFT - draft-elkins-6man-ipv6-pdm-dest-option
draft-elkins-6man-ipv6-pdm-dest-option
INTERNET-DRAFT N. Elkins
Inside Products
R. Hamilton
Chemical Abstracts Service
M. Ackermann
Intended Status: Proposed Standard BCBS Michigan
Expires: April 2015 October 20, 2014
IPv6 Performance and Diagnostic Metrics Destination Option
draft-elkins-6man-ipv6-pdm-dest-option-09
Abstract
To assess performance problems, measurements based on optional
sequence numbers and timing may be embedded in each packet. Such
measurements may be interpreted in real-time or after the fact. This
document describes an implementation of the existing IPv6 Destination
Options extension header, the Performance and Diagnostic Metrics
(PDM) Destination Options extension header. A discussion of the
field limits, calculations, and usage of the PDM in measurement is
described in a companion document.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
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Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html
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Copyright and License Notice
Copyright (c) 2014 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
(http://trustee.ietf.org/license-info) in effect on the date of
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Performance and Diagnostic Metrics Destination Option . . . . . 3
2.1 Destination Options Header . . . . . . . . . . . . . . . . 3
2.2 Performance and Diagnostic Metrics Destination Option . . . 4
2.3 Time Base . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.4 Timer-value scaling . . . . . . . . . . . . . . . . . . . . 7
2.5 Header Placement . . . . . . . . . . . . . . . . . . . . . 8
2.6 Implementation Considerations . . . . . . . . . . . . . . . 9
2.6.1 Dynamic Configuration Options . . . . . . . . . . . . . 9
2.6.2 Data Length Filtering . . . . . . . . . . . . . . . . . 9
2.6.3 5-tuple Aging . . . . . . . . . . . . . . . . . . . . . 9
3 Backward Compatibility . . . . . . . . . . . . . . . . . . . . 10
4 Security Considerations . . . . . . . . . . . . . . . . . . . . 10
5 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 10
6 References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.2 Informative References . . . . . . . . . . . . . . . . . . . 11
7 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
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1 Introduction
To assess performance problems, measurements based on optional
sequence numbers and timing may be embedded in each packet. Such
measurements may be interpreted in real-time or after the fact. This
document describes an implementation of the existing IPv6 Destination
Options extension header, the Performance and Diagnostic Metrics
(PDM) Destination Options extension header. A discussion of the
field limits, calculations, and usage of the PDM in measurement is
described in a companion document :"IPPM Considerations for the IPv6
PDM Destination Option" [ELK-IPPM]. [ELK-IPPM] discusses measurement
of end-user Quality of Experience (QoE) as well as the details of the
scaling factors used. The current document describes the fields in
the PDM header itself.
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 (PDM)
destination option.
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].
The IPv6 Performance and Diagnostic Metrics Destination Option (PDM)
is an implementation of the IPv6 Destination Options extension header
(Next Header value = 60). The PDM does not require time
synchronization.
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2.2 Performance and Diagnostic Metrics Destination Option
The Performance and Diagnostic Metrics Destination Option (PDM)
contains the following fields:
TIMEBASE : Base timer unit
SCALEDL : Scale for Delta Last Received
SCALEDS : Scale for Delta Last Sent
PSNTP : Packet Sequence Number This Packet
PSNLR : Packet Sequence Number Last Received
DELTALR : Delta Last Received
DELTALS : Delta Last Sent
For a full explanation of the SCALEDL, SCALEDS, DELTALR, DELTALS
fields, see [ELK-IPPM].
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 |TB |ScaleDL | ScaleDS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PSN This Packet | PSN Last Received |
|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Delta Last Received | Delta Last Sent |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
16.
Time Base
2-bit unsigned integer. It will indicate the unit measurement for
this device. That is, for a value of 11 in the Time Base field, a
value of 1 in the DELTA fields indicates this device has incremented
the time by 1 picosecond. Similarly, for a value of 01 in the Time
Base field, a DELTA value of 1 indicates an increment of 1
microsecond.
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The possible values of Time Base are as follows:
00 - milliseconds
01 - microseconds
10 - nanoseconds
11 - picoseconds
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.
Packet Sequence Number Last Received (PSNLR)
16-bit unsigned integer. This is the PSN of the packet last received
on the 5-tuple.
Scale Delta Last Received (SCALEDLR)
7-bit signed integer. This is the scaling value for the Delta Last
Received (DELTALR) field. The possible values are from -64 to +63.
Scale Delta Last Sent (SCALEDLS)
7-bit signed integer. This is the scaling value for the Delta Last
Sent (DELTALS) field. The possible values are from -64 to +63.
Delta Last Received (DELTALR)
A 16-bit unsigned integer field.
DELTALR = Send time packet 2 - Receive time packet 1
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The value is according to the scale in SCALEDLR.
Delta Last Sent (DELTALS)
A 16-bit unsigned integer field.
Delta Last Sent = Receive time packet 2 - Send time packet 1
The value is in according to the scale in SCALEDLS.
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
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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
the low-order 5 bits of an Option Type.
2.3 Time Base
This specification allows for the fact that different CPU TOD clocks
use different binary points. For some clocks, a value of 1 could
indicate 1 microsecond, whereas other clocks could use the value 1 to
indicate 1 millisecond. In the former case, the binary digits to the
right of that binary point measure 2**(-n) microseconds, and in the
latter case, 2**(-n) milliseconds.
The Time Base allows us to ensure we have a common reference, at the
very least, common knowledge of what the binary point is for the
transmitted values.
2.4 Timer-value scaling
As discussed in [TRAM-TCPM] we propose storing not an entire time-
interval value, but just the most significant bits of that value,
along with a scaling factor to indicate the magnitude of the time-
interval value. In our case, we will use the high-order 16 bits. The
scaling value will be the number of bits in the timer register to the
right of the 16th significant bit. That is, if the timer register
contains this binary value:
1110100011010100101001010001000000000000
<-16 bits -><-24 bits ->
then, the values stored would be 1110 1000 1101 0100 in binary (E8D4
hexadecimal) for the time value and 24 for the scaling value. Note
that the displayed value is the binary equivalent of 1 second
expressed in picoseconds.
The following table represents a device which has a TimeBase of
picosecond (or 11). For this Time Base value the smallest and
simplest time value to represent is 1 picosecond; the encoded value
is 1, and the scaling value is 0. Using time values in the first
column in the table below, we create the following encoded values and
scaling values:
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Time value in Encoded Scaling
Delta time picoseconds value decimal
-----------------------------------------------------
1 picosecond 1 0001 0
1 nanosecond 3e8 03e8 0
1 microsecond f4240 f424 4
1 millisecond 3b9aca00 3b9a 16
1 second e8d4a51000 e8d4 24
1 minute 3691d6afc000 3691 32
1 hour cca2e51310000 cca2 36
1 day 132f4579c980000 132f 44
365 days 1b5a660ea44b80000 1b5a 52
Sample binary values (high order 16 bits taken)
1 psec 1 0001
1 nsec 3e8 0011 1110 1000
1 usec f4240 1111 0100 0010 0100 0000
1 msec 3b9aca00 0011 1011 1001 1010 1100 1010 0000 0000
1 sec e8d4a51000 1110 1000 1101 0100 1010 0101 0001 0000 0000 0000
The need for a signed scaling value is more apparent when the Time
Base is lower. If you specify your Time Base is microseconds (or 01)
then these tables looks very similar:
Time value in Encoded Scaling
Delta time microseconds value decimal
--------------------------------------------------------
1 microsecond 1 0001 0
1 millisecond 3e8 03e8 0
1 second f4240 f424 4
1 minute 3938700 e4e1 10
1 hour d693a400 d693 16
1 day 141dd76000 a0ee 21
An issue arises when the binary point is at the microsecond level, as
it is here, but the time differential to be expressed is some number
of nanoseconds or picoseconds. For example 1 nanosecond is .001
microseconds, or about .000000000100000110001001001 in binary. To
encode this value we would follow the same procedure:
<- 25 bits -> Scaling value: -25
000000000100000110001001001
<-16 bits -> Encoded value: 8312
So, the encoded value would be 8312, with a scaling value of -25
which, in the signed 7-bit SCALEDS or SCALEDR field would be
represented as 1100111 in binary.
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Similarly, if the Time Base is 10, indicating the clock is counting
nanoseconds, the encoded value and scaling values for 1 picosecond,
or .001 nanoseconds are the same, 8312 and -25, because we've changed
the Time Base.
For further discussion on timing and scaling, please see "IPPM
Considerations for the IPv6 PDM Destination Option" [ELK-IPPM].
2.5 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.
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2.6 Implementation Considerations
The PDM destination options extension header SHOULD be turned on by
each stack on a host node.
2.6.1 Dynamic Configuration Options
If implemented, each operating system MUST have a default
configuration parameter, e.g. diag_header_sys_default_value=yes/no.
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.
2.6.2 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 0 or 1 byte data length.
2.6.3 5-tuple Aging
Within the operating system, metrics must be kept on a 5-tuple basis.
The 5-tuple is:
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)
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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.
So, the recommendation is to use a known aging parameter such as Max
Segment Lifetime (MSL) as defined in Transmission Control Protocol
[RFC0793]. The choice of aging parameter is left up to the
implementation.
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 (PDM) destination option.
6 References
6.1 Normative References
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC
793, September 1981.
[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.
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6.2 Informative References
[TRAM-TCPM] Trammel, B., "Encoding of Time Intervals for the TCP
Timestamp Option-01", Internet Draft, July 2013. [Work in Progress]
[ELK-IPPM] Elkins, N., "IPPM Considerations for the IPv6 PDM
Destination Option-02", Internet Draft, October 2014.
7 Acknowledgments
The authors would like to thank Keven Haining, Bill Jouris, Sigfrido
Perdomo, and Al Morton 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
Robert M. Hamilton
Chemical Abstracts Service
A Division of the American Chemical Society
2540 Olentangy River Road
Columbus, Ohio 43202
United States
Phone: +1 614 447 3600 x2517
Email: rhamilton@cas.org
http://www.cas.org
Michael S. Ackermann
Blue Cross Blue Shield of Michigan
P.O. Box 2888
Detroit, Michigan 48231
United States
Phone: +1 310 460 4080
Email: mackermann@bcbsmi.com
http://www.bcbsmi.com
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