Internet DRAFT - draft-hedin-ippm-type-p-monitor
draft-hedin-ippm-type-p-monitor
Network Working Group J. Hedin
Internet-Draft G. Mirsky
Intended status: Standards Track S. Baillargeon
Expires: April 3, 2015 Ericsson
September 30, 2014
Differentiated Service Code Point and Explicit Congestion Notification
Monitoring in Two-Way Active Measurement Protocol (TWAMP)
draft-hedin-ippm-type-p-monitor-04
Abstract
This document describes an OPTIONAL feature for TWAMP [RFC5357]
allowing the monitoring of the Differentiated Service Code Point and
Explicit Congestion Notification fields with the TWAMP-Test protocol.
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 April 3, 2015.
Copyright 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
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.
Hedin, et al. Expires April 3, 2015 [Page 1]
Internet-Draft DSCP and ECN Monitoring in TWAMP September 2014
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions used in this document . . . . . . . . . . . . 3
1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3
1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3
2. TWAMP Extensions . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Setting Up Connection to Monitor DSCP and ECN . . . . . . 3
2.2. TWAMP-Test Extension . . . . . . . . . . . . . . . . . . 4
2.2.1. Session-Reflector Packet Format for DSCP and ECN
Monitoring . . . . . . . . . . . . . . . . . . . . . 4
2.2.2. DSCP and ECN Monitoring with RFC 6038 extensions . . 7
2.2.3. Consideration for TWAMP Light mode . . . . . . . . . 8
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
4. Security Considerations . . . . . . . . . . . . . . . . . . . 8
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.1. Normative References . . . . . . . . . . . . . . . . . . 9
6.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
One-Way Active Measurement Protocol (OWAMP) [RFC4656] defines Type-P
descriptor and negotiation of its value in OWAMP-Control protocol.
Two-Way Active Measurement Protocol (TWAMP) [RFC5357] states that
only Differentiated Service Code Point (DSCP) value can be defined by
Type-P descriptor and the negotiated value must be used by both
Session-Sender and Session-Reflector. The TWAMP specification also
states that the same value of DSCP (found in the Session-Sender
packet) MUST be used in the test packet reflected by the Session-
Reflector. However the TWAMP-Test protocol does not specify any
methods to determine or report when the DSCP value has changed or is
different than expected in the forward or reverse direction. Re-
marking the DSCP (changing its original value) in IP networks is
possible and often accomplished by a Diffserv policy configured o a
single node along the IP path. In many cases, a change of the DSCP
value of indicates an unintentional or errorneous behavior. At best,
the Session-Sender can detect a change of the DSCP reverse direction
assuming such change is actually detectable.
This document describes an OPTIONAL feature for TWAMP. It is called
the DSCP and ECN monitoring feature. This feature allows the
Session-Sender to know the actual DSCP value received at the Session-
Reflector. Furthermore this OPTIONAL feature also tracks the
Explicit Congestion Notification (ECN) value received at the Session-
Reflector. This is helpful to determine if ECN is actually operating
Hedin, et al. Expires April 3, 2015 [Page 2]
Internet-Draft DSCP and ECN Monitoring in TWAMP September 2014
or if an ECN-capable node has detected congestion in the forward
direction.
1.1. Conventions used in this document
1.1.1. Terminology
DSCP: Differentiated Service Codepoint
ECN: Explicit Congestion Notification
IPPM: IP Performance Measurement
TWAMP: Two-Way Active Measuremnt Protocol
OWAMP: One-Way Active Measurement Protocol
1.1.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119].
2. TWAMP Extensions
TWAMP connection establishment follows the procedure defined in
Section 3.1 of [RFC4656] and Section 3.1 of [RFC5357] where the Modes
field been used to identify and select specific communication
capabilities. At the same time the Modes field been recognized and
used as extension mechanism [RFC6038]. The new feature requires new
bit position to identify the ability of a Session-Reflector to return
value of received DSCP and ECN values back to a Session-Sender, and
to support the new Session-Reflector packet format in the TWAMP-Test
protocol. See the Section 3 for details on the assigned value and
bit position.
2.1. Setting Up Connection to Monitor DSCP and ECN
The Server sets DSCP and ECN Monitoring flag in Modes field of the
Server Greeting message to indicate its capabilities and willingness
to monitor them. If the Control-Client agrees to monitor DSCP and
ECN on some or all test sessions invoked with this control
connection, it MUST set the DSCP and ECN Monitoring flag in Modes
field in the Setup Response message.
Hedin, et al. Expires April 3, 2015 [Page 3]
Internet-Draft DSCP and ECN Monitoring in TWAMP September 2014
2.2. TWAMP-Test Extension
Monitoring of DSCP and ECN requires support by Session-Reflector and
changes format of its test packet format both in unauthenticated,
authenticated and encrypted modes. Monitoring of DSCP and ECN does
not alter Session-Sender test packet format but certain
considerations must be taken when and if this mode is accepted in
combination with Symmetrical Size mode[RFC6038].
2.2.1. Session-Reflector Packet Format for DSCP and ECN Monitoring
When Session-Reflector supports DSCP and ECN Monitoring it MUST
construct Sender DSCP and ECN (S-DSCP-ECN) field for each test packet
it sends to Session-Sender according to the following procedure:
- first six bits MUST be copied Differentiated Service field from
received Session-Sender test packet into Sender DSCP (S-DSCP)
field;
- following two bits MUST be copied ECN field from received
Session-Sender test packet into Sender ECN (S-ECN) field.
0 1 2 3 4 5 6 7 8
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| S-DSCP | S-ECN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Sender DSCP and ECN field format
For unauthenticated mode:
Hedin, et al. Expires April 3, 2015 [Page 4]
Internet-Draft DSCP and ECN Monitoring in TWAMP September 2014
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Estimate | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receive Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Error Estimate | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender TTL | S-DSCP-ECN | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
. .
. Packet Padding .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Session-Reflector test packet format with DSCP and ECN
monitoring in unauthenticated mode
For authenticated and encrypted modes:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| MBZ (12 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Estimate | |
Hedin, et al. Expires April 3, 2015 [Page 5]
Internet-Draft DSCP and ECN Monitoring in TWAMP September 2014
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| MBZ (6 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receive Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (8 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| MBZ (12 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Error Estimate | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| MBZ (6 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender TTL | S-DSCP-ECN | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
+ +
| MBZ (14 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| HMAC (16 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Packet Padding .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Session-Reflector test packet format with DSCP and ECN
monitoring in authenticated or encrypted modes
The DSCP value is often copied into reflected test packets with
current TWAMP implementations (with or without TWAMP-Control
protocol). With DSCP and ECN Monitoring Extenstion Session-Reflector
handles DSCP as following:
Hedin, et al. Expires April 3, 2015 [Page 6]
Internet-Draft DSCP and ECN Monitoring in TWAMP September 2014
The Session-Reflector MUST extracts the S-DSCP-ECN value from the
DSCP and ECN values of received packets;
The Session-Reflector MUST transmit each reflected test packet
with DSCP set to the negotiated/provisioned value;
If the negotiated/provisioned DSCP value is not known (e.g. TWAMP
Light), the choice of the DSCP is implementation specific. For
instance, Session-Reflector MAY copy the DSCP value from the
received test packet and set it as DSCP in a reflected packet.
2.2.2. DSCP and ECN Monitoring with RFC 6038 extensions
[RFC6038] defined two extensions to TWAMP. First, to ensure that
Session-Sender and Session-Reflector exchange TWAMP-Test packets of
equal size. Second, to specify number of octets to be reflected by
Session-Reflector. If DSCP and ECN monitoring and Symmetrical Size
and/or Reflects Octets modes being negotiated between Server and
Control-Client in Unauthenticated mode, then because Sender DSCP and
Sender ECN increase size of unauthenticated Session-Reflector packet
by 4 octets the Padding Length value SHOULD be >= 28 octets to allow
for the truncation process that TWAMP recommends in Section 4.2. 1 of
[RFC5357].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Estimate | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
| MBZ (28 octets) |
| |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
. .
. Packet Padding .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Session-Sender test packet format with DSCP and ECN
monitoring and Symmetrical Test Packet in unauthenticated mode
Hedin, et al. Expires April 3, 2015 [Page 7]
Internet-Draft DSCP and ECN Monitoring in TWAMP September 2014
2.2.3. Consideration for TWAMP Light mode
Appendix I of [RFC5357] does not explicitly state how value of Type-P
descriptor synchronized between Session-Sender and Session-Reflector
and whether different values considered as error condition and should
be reported. We assume that by some means Session-Sender and
Session-Reflector of given TWAMP-Test session informed to use the
same DSCP value. Same means, i.e. configuration, could be used to
inform Session-Reflector to support DSCP and ECN monitoring mode by
copying data from received TWAMP test packets. Then Session-Sender
may be informed to use Sender DSCP and ECN field in reflected TWAMP
test packet.
3. IANA Considerations
The TWAMP-Modes registry defined in [RFC5618].
IANA is requested to reserve a new DSCP and ECN Monitoring Capability
as follows:
+------------+--------------------+---------------------+-----------+
| Value | Description | Semantics | Reference |
+------------+--------------------+---------------------+-----------+
| X | DSCP and ECN | bit position Y | This |
| (proposed | Monitoring | (proposed 7) | document |
| 128) | Capability | | |
+------------+--------------------+---------------------+-----------+
Table 1: New Type-P Descriptor Monitoring Capability
4. Security Considerations
Monitoring of DSCP and ECN does not appear to introduce any
additional security threat to hosts that communicate with TWAMP as
defined in [RFC5357], and existing extensions [RFC6038]. The
security considerations that apply to any active measurement of live
networks are relevant here as well. See the Security Considerations
sections in [RFC4656] and [RFC5357].
5. Acknowledgements
Authors greatly appreciate thorough review and thoughtful comments by
Chritofer Flinta and Samita Chakrabarti.
Hedin, et al. Expires April 3, 2015 [Page 8]
Internet-Draft DSCP and ECN Monitoring in TWAMP September 2014
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.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474, December
1998.
[RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
Zekauskas, "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, September 2006.
[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, October 2008.
[RFC5618] Morton, A. and K. Hedayat, "Mixed Security Mode for the
Two-Way Active Measurement Protocol (TWAMP)", RFC 5618,
August 2009.
[RFC6038] Morton, A. and L. Ciavattone, "Two-Way Active Measurement
Protocol (TWAMP) Reflect Octets and Symmetrical Size
Features", RFC 6038, October 2010.
6.2. Informative References
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
Authors' Addresses
Jonas Hedin
Ericsson
Email: jonas.hedin@ericsson.com
Hedin, et al. Expires April 3, 2015 [Page 9]
Internet-Draft DSCP and ECN Monitoring in TWAMP September 2014
Greg Mirsky
Ericsson
Email: gregory.mirsky@ericsson.com
Steve Baillargeon
Ericsson
Email: steve.baillargeon@ericsson.com
Hedin, et al. Expires April 3, 2015 [Page 10]
