Network Working Group A. Morton
Internet-Draft AT&T Labs
Intended status: Standards Track M. Chiba
Expires: April 26, 2010 Cisco Systems
October 23, 2009
Individual Session Control Feature for TWAMP
draft-ietf-ippm-twamp-session-cntrl-02
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. This document may contain material
from IETF Documents or IETF Contributions published or made publicly
available before November 10, 2008. The person(s) controlling the
copyright in some of this material may not have granted the IETF
Trust the right to allow modifications of such material outside the
IETF Standards Process. Without obtaining an adequate license from
the person(s) controlling the copyright in such materials, this
document may not be modified outside the IETF Standards Process, and
derivative works of it may not be created outside the IETF Standards
Process, except to format it for publication as an RFC or to
translate it into languages other than English.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on April 26, 2010.
Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
Morton & Chiba Expires April 26, 2010 [Page 1]
Internet-Draft TWAMP Session Control October 2009
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents in effect on the date of
publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document.
Abstract
The IETF has completed its work on the core specification of TWAMP -
the Two-Way Active Measurement Protocol. This memo describes a new
feature for TWAMP, that gives the controlling host the ability to
start and stop one or more individual test sessions using Session
Identifiers. The base capability of the TWAMP protocol requires all
test sessions previously requested and accepted to start and stop at
the same time.
Requirements Language
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].
Morton & Chiba Expires April 26, 2010 [Page 2]
Internet-Draft TWAMP Session Control October 2009
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . 4
3. TWAMP Control Extensions . . . . . . . . . . . . . . . . . . . 5
3.1. Connection Setup with Individual Session Control . . . . . 5
3.2. Start-N-Sessions Command with Individual Session
Control . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3. Start-N-Ack Command with Individual Session Control . . . 9
3.4. Stop-N-Sessions Command with Individual Session Control . 10
3.5. Stop-N-Ack Command with Individual Session Control . . . . 11
3.6. SERVWAIT Timeout Operation . . . . . . . . . . . . . . . . 13
3.7. Additional considerations . . . . . . . . . . . . . . . . 14
4. TWAMP Test with Individual Session Control . . . . . . . . . . 14
4.1. Sender Behavior . . . . . . . . . . . . . . . . . . . . . 14
4.2. Reflector Behavior . . . . . . . . . . . . . . . . . . . . 14
5. Security Considerations . . . . . . . . . . . . . . . . . . . 15
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
6.1. Registry Specification . . . . . . . . . . . . . . . . . . 15
6.2. Registry Management . . . . . . . . . . . . . . . . . . . 15
6.3. Experimental Numbers . . . . . . . . . . . . . . . . . . . 16
6.4. Registry Contents . . . . . . . . . . . . . . . . . . . . 16
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8.1. Normative References . . . . . . . . . . . . . . . . . . . 17
8.2. Informative References . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
Morton & Chiba Expires April 26, 2010 [Page 3]
Internet-Draft TWAMP Session Control October 2009
1. Introduction
The IETF has completed its work on the core specification of TWAMP -
the Two-Way Active Measurement Protocol [RFC5357]. TWAMP is an
extension of the One-way Active Measurement Protocol, OWAMP
[RFC4656]. The TWAMP specification gathered wide review as it
approached completion, and the by-products were several
recommendations for new features in TWAMP. There are a growing
number of TWAMP implementations at present, and wide-spread usage is
expected. There are even devices that are designed to test
implementations for protocol compliance.
This memo describes a new feature for TWAMP. TWAMP (and OWAMP) start
all previously requested and accepted test sessions at once. This
feature allows the Control-Client to control individual test sessions
on the basis of their Session Identifier (SID). This feature permits
a short duration TWAMP test to start (and/or stop) during a longer
test. This feature permits a specific diagnostic test to begin if
intermediate results indicate that the test is warranted, for
example.
This feature requires a Mode bit position assignment and the
assignment of two new TWAMP command numbers (for the augmented Start
and Stop commands). This feature also specifies a new Stop-ACK
Server response, to complete the symmetry of the session stopping
process in the same way as the Start-ACK response.
Implementers of this feature may also wish to implement the "Reflect
Octets" feature, described in [I-D.ietf-ippm-twamp-reflect-octets].
This feature allows a Control-Client to insert a locally-specified
request number into the Request-TW-Session command (in octets
originally designated MBZ=Must Be Zero), and a compliant Server will
return the request number in its reply (Accept message).
This memo is intended to be an update to the TWAMP RFC.
Throughout this memo, the bits marked MBZ (Must Be Zero) MUST be set
to zero by senders and MUST be ignored by receivers.
2. Purpose and Scope
The purpose of this memo is to describe an additional function and
feature for TWAMP [RFC5357]. The feature needs a clear description
so it can be discussed and (hopefully) adopted in the IP Performance
Metrics Charter.
The scope of the memo is currently limited to specifications of the
Morton & Chiba Expires April 26, 2010 [Page 4]
Internet-Draft TWAMP Session Control October 2009
following features:
1. Extension of the modes of operation through assignment of a new
value in the Mode field to communicate feature capability and
use,
2. the definitions of augmented start session and stop session
commands (with corresponding acknowledgements), and
3. the definition of related procedures for TWAMP entities.
The motivation for this feature is the ability to start and stop
individual test sessions at will, using a single TWAMP-control
connection.
When the Server and Control-Client have agreed to use the Individual
Session Control mode during control connection setup, then the
Control-Client, the Server, the Session-Sender, and the Session-
Reflector MUST all conform to the requirements of that mode, as
identified below. The original TWAMP-Control Start and Stop commands
MUST NOT be used.
3. TWAMP Control Extensions
TWAMP-Control protocol is a derivative of the OWAMP-Control protocol,
and provides two-way measurement capability. TWAMP [RFC5357] uses
the Modes Field to identify and select specific communication
capabilities, and this field is a recognized extension mechanism.
The following sections describe one such extension.
3.1. Connection Setup with Individual Session Control
TWAMP-Control connection establishment follows the procedure defined
in section 3.1 of [RFC4656] OWAMP. The Individual Session Control
mode requires one new bit position (and value) to identify the
ability of the Server/Session-Reflector to start and stop specific
sessions (according to their Session Identifier, or SID). This new
feature requires an additional TWAMP mode bit assignment as follows:
Morton & Chiba Expires April 26, 2010 [Page 5]
Internet-Draft TWAMP Session Control October 2009
Value Description Reference/Explanation
0 Reserved
1 Unauthenticated RFC4656, Section 3.1
2 Authenticated RFC4656, Section 3.1
4 Encrypted RFC4656, Section 3.1
8 Unauth. TEST protocol, draft-...-more-twamp (3)
Auth. CONTROL
--------------------------------------------------------
zzz Individual Session this memo, bit position (Z)
Control
In the original OWAMP mode field, setting bit positions 0, 1 or 2
indicated the security mode of the Control protocol, and the Test
protocol inherited the same mode (see section 4 of [RFC4656]). In
the [RFC5618] memo, bit position (3) allows a different security mode
in the Test protocol and uses the unauthenticated test packet format.
If the Server sets the new bit position (bit position Z) in the
Server Greeting message to indicate its capabilities, then the Server
and Session-Reflector MUST comply with the requirements of this memo
to control sessions on an individual basis if desired.
If the Control-Client intends to control sessions on an individual
basis (according to the requirements in this memo), it MUST set the
mode bit (Z, corresponding to the new mode) in the Setup Response
message. This means that:
1. The Control-Client and the Server MUST use the start and stop
commands intended for individual session control and the
corresponding acknowledgements, as defined in the sections that
follow.
2. The Control-Client and the Server MUST NOT use the start and stop
commands (2 and 3) and the acknowledgement defined in [RFC5357].
The Control-Client MUST also set one mode bit to indicate the chosen
security mode (currently bits 0, 1, 2, or 3), consistent with the
modes offered by the Server. The Control-Client MAY also set Modes
bit Z with other features and bit positions (such as the reflect
octets feature).
If the Control-Client has selected the Reflect Octets feature
[I-D.ietf-ippm-twamp-reflect-octets] in combination with the
Individual Session Control feature (after the Server identified its
capability), AND utilizes the feature to insert a locally-specified
request number in the Request-TW-Session command, THEN the Control
Client MAY send more than one Request-TW-Session command to a given
Morton & Chiba Expires April 26, 2010 [Page 6]
Internet-Draft TWAMP Session Control October 2009
Server without waiting for the corresponding Accept-Session message.
In such a case the Access-Session response reflects the locally-
specified request number. Note that when the Reflect Octets feature
is being used all Request-TW-Session command and Accept-Session
responses MUST include the locally-specified request number.
3.2. Start-N-Sessions Command with Individual Session Control
Having
o initiated Individual Session Control mode in the Setup Response,
o requested one or more test sessions, and
o received affirmative Accept-Session response(s),
a TWAMP Client MAY start the execution of one or more test sessions
by sending a Start-N-Sessions message to the Server (note that "N"
indicates that this command is applicable to one or more sessions,
and does not change with the number of sessions identified in the
command).
The format of the Start-N-Sessions message is as follows:
Morton & Chiba Expires April 26, 2010 [Page 7]
Internet-Draft TWAMP Session Control October 2009
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| 7 | |
+-+-+-+-+-+-+-+-+ +
| MBZ (11 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Sessions |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| |
| First SID (16 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| |
. remaining SIDs (16 octets each) .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| |
| HMAC (16 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
The Command Number value of 7 indicates that this is a Start-N-
Sessions command. The Control-Client MUST compose this command, and
the Server MUST interpret this command, according to the field
descriptions below.
The Number of Sessions field indicates the count of sessions that
this Start command applies to, and must be one or greater. The
number of SID fields that follow MUST be equal to the value in the
Number of Sessions field (otherwise, the command MUST NOT be affirmed
with a zero Accept field in the Start-N-Ack response).
All SID fields are constructed as defined in the last paragraph of
OWAMP section 3.5 [RFC4656] (and referenced in TWAMP). Note that the
SID is assigned by the Server during the session request exchange.
The message is terminated with a single block HMAC, as illustrated
above.
The Server MUST respond with one or more Start-N-Ack messages (which
SHOULD be sent as quickly as possible). Start-N-Ack messages SHALL
have the format defined in the next session.
Morton & Chiba Expires April 26, 2010 [Page 8]
Internet-Draft TWAMP Session Control October 2009
When using Individual Session Control mode and its Start-N-Ack
command as described in the next section, multiple Start-N-Sessions
commands MAY be sent without waiting for acknowledgement, and the
Start-N-sessions commands MAY arrive in any order.
3.3. Start-N-Ack Command with Individual Session Control
The Server responds to the Start-N-Sessions command (for one or more
specific sessions referenced by their SIDs) with one or more Start-N-
Ack commands with Accept fields corresponding to one or more of the
SIDs. This allows for the possibility that a Server cannot
immediately start one or more the sessions referenced in a particular
Start-N-Sessions command, but can start one or more of the sessions.
The format of the message is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| 8 | Accept | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (8 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Sessions |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| |
| First SID (16 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| |
. remaining SIDs (16 octets each) .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| |
| HMAC (16 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Command Number value of 8 indicates that this is a Start-N-Ack
message. The Server MUST compose this command, and the Control-
Client MUST interpret this command, according to the field
descriptions below.
The Accept Field values are defined in OWAMP section 3.3 [RFC4656].
Morton & Chiba Expires April 26, 2010 [Page 9]
Internet-Draft TWAMP Session Control October 2009
The Number of Sessions field indicates the count of sessions that
this Start-N-Ack command applies to, and must be one or greater. The
number of SID fields that follow MUST be equal to the value in the
Number of Sessions field.
All SID fields are constructed as defined in the last paragraph of
OWAMP section 3.5 [RFC4656] (and referenced in TWAMP). Note that the
SID is assigned by the Server during the session request exchange.
The message is terminated with a single block HMAC, as illustrated
above.
Note that the SIDs for all Sessions with the same 'Accept' code can
be acknowledged using the same Start-N-Ack message.
For example, say that the Server receives a Start-N-Sessions command
for SIDs 1, 2, 3, and 4. The Server determines that the resources
for SID=3 are temporarily unavailable. The Server responds with two
Start-N-Ack commands with fields as follows:
Accept = 0 Number of Sessions = 3 SIDs 1, 2, 4
Accept = 5 Number of Sessions = 1 SID 3
3.4. Stop-N-Sessions Command with Individual Session Control
The Stop-N-Sessions command can only be issued by the Control-Client.
The command MUST contain at least one SID.
The TWAMP Stop-N-Sessions command for use in Individual Session
Control mode is formatted as follows:
Morton & Chiba Expires April 26, 2010 [Page 10]
Internet-Draft TWAMP Session Control October 2009
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| 9 | |
+-+-+-+-+-+-+-+-+ +
| MBZ (11 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Sessions |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| |
| First SID (16 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| |
. remaining SIDs (16 octets each) .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| |
| HMAC (16 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
The Command Number value of 9 indicates that this is a Stop-N-
Sessions command. The Control-Client MUST compose this command, and
the Server MUST interpret this command, according to the field
descriptions below.
The Number of sessions field indicates the count of sessions that
this Stop-N-Sessions command applies to. The SID is as defined in
OWAMP (and TWAMP) section 3.5 [RFC4656] and the value must be one or
greater. The number of SID fields that follow MUST be equal to the
value in the Number of Sessions field.
The message is terminated with a single block HMAC, as illustrated
above.
The Server MUST respond with one or more Stop-N-Ack messages (which
SHOULD be sent as quickly as possible). Stop-N-Ack messages SHALL
have the format defined in the next session.
3.5. Stop-N-Ack Command with Individual Session Control
In response to the Stop-N-Sessions command (for one or more specific
sessions referenced by their SIDs), the Server MUST reply with one or
Morton & Chiba Expires April 26, 2010 [Page 11]
Internet-Draft TWAMP Session Control October 2009
more Stop-N-Ack commands with Accept fields corresponding to one or
more of the SIDs. This allows for the possibility that a Server
cannot immediately stop one or more the sessions referenced in a
particular Stop-N-Sessions command, but can stop one or more of the
sessions.
The format for the Stop-N-Ack command is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| 10 | Accept | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (8 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Sessions |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| |
| First SID (16 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| |
. remaining SIDs (16 octets each) .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+B
| |
| HMAC (16 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Command Number value of 10 indicates that this is a Stop-N-Ack
message. The Server MUST compose this command, and the Control-
Client MUST interpret this command, according to the field
descriptions below.
The Accept Field values are defined in OWAMP section 3.3 [RFC4656].
The Number of Sessions field indicates the count of sessions that
this Stop-N-Ack command applies to, and must be one or greater. The
number of SID fields that follow MUST be equal to the value in the
Number of Sessions field.
All SID fields are constructed as defined in the last paragraph of
OWAMP section 3.5 [RFC4656] (and referenced in TWAMP). Note that the
Morton & Chiba Expires April 26, 2010 [Page 12]
Internet-Draft TWAMP Session Control October 2009
SID is assigned by the Server during the session request exchange.
The message is terminated with a single block HMAC, as illustrated
above.
Note that the SIDs for all Sessions with the same 'Accept' code can
be acknowledged using the same Stop-N-Ack message.
3.6. SERVWAIT Timeout Operation
Section 3.1 of [RFC5357] describes the operation of the optional
SERVWAIT timer. In normal TWAMP operation, the Server suspends
monitoring the SERVWAIT timer while test sessions are in progress.
When the Individual Session Control feature is utilized, this
suspension is extended to cover the time when ANY test session is in
progress.
Thus, the Server SHALL suspend monitoring control connection activity
after receiving any Start-N-Sessions command, and after receiving a
Stop-N-Sessions command for all corresponding SIDs (and no test
sessions are in-progress), OR when REFWAIT expires on ALL test
sessions initiated by a TWAMP-Control connection, then the SERVWAIT
monitoring SHALL resume (as though a Stop-N-Sessions command had been
received). An implementation which supports the SERVWAIT timeout
option SHOULD also implement the REFWAIT timeout option.
The diagram below illustrates the operation of timers SERVWAIT and
REFWAIT.
SERVWAIT REFWAIT SERVWAIT
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+
(no sessions
in-progress)
+-+-+-+-+-+-+-+-+-+-+-+
SID="1"
+-+-+-+-+
SID="2"
+-+-+-+-+-+-+-+-+
SID="3"
>>>>>>>>>> Time >>>>>>>>>>>>>>>>>>> Time >>>>>>>>>>>>>>>> Time >>>>>
Morton & Chiba Expires April 26, 2010 [Page 13]
Internet-Draft TWAMP Session Control October 2009
3.7. Additional considerations
The value of the Modes field sent by the Server (in the Server
Greeting message) is the bit-wise OR of the mode values that it is
willing to support during this session.
If this feature is adopted, the last ???? bits of the Modes 32-bit
field are used. A Control-Client MAY ignore other bit positions
greater than 2 in the Modes Field, or it MAY support other features
that are communicated in these bit positions. (The unassigned bits
are available for future protocol extensions.)
Other ways in which TWAMP extends OWAMP are described in [RFC5357].
4. TWAMP Test with Individual Session Control
The TWAMP test protocol is similar to the OWAMP [RFC4656] test
protocol with the exception that the Session-Reflector transmits test
packets to the Session-Sender in response to each test packet it
receives. TWAMP [RFC5357] defines two different test packet formats,
one for packets transmitted by the Session-Sender and one for packets
transmitted by the Session-Reflector. As with OWAMP-Test protocol
there are three security modes: unauthenticated, authenticated, and
encrypted. Unauthenticated mode has one test packet format, while
authenticated and encrypted modes use another (common) format.
4.1. Sender Behavior
The individual session control feature requires that the sender MUST
manage test sessions according to their SID. Otherwise, the sender
behavior is as described in section 4.1 of [RFC5357].
4.2. Reflector Behavior
The TWAMP Reflector follows the procedures and guidelines in section
4.2 of [RFC5357], with the following additional functions required by
this feature:
o The Session-Reflector MUST manage all test sessions accepted
according to their SID.
o Upon receipt of a TWAMP-Control Stop-N-Sessions command
referencing a specific session/SID, the Session-Reflector MUST
ignore TWAMP-Test packets (in the same session/SID) that arrive at
the current time plus the Timeout (in the Request-TW-Session
command and assuming subsequent acknowledgement). The Session-
Reflector MUST NOT generate a test packet to the Session-Sender
Morton & Chiba Expires April 26, 2010 [Page 14]
Internet-Draft TWAMP Session Control October 2009
for packets that are ignored.
o If the RECOMMENDED REFWAIT timer is implemented, it SHOULD be
enforced when any test session is in-progress (started and not
stopped).
5. Security Considerations
The security considerations that apply to any active measurement of
live networks are relevant here as well. See the security
considerations in[RFC4656] and [RFC5357].
6. IANA Considerations
This memo requests assignment of one mode bit position/value to the
IANA registry for the TWAMP Mode field, and describes behavior when
the new mode is used. This field is a recognized extension mechanism
for TWAMP.
This memo also requests assignment of four command numbers in the
TWAMP-Control Command Number registry, and describes the use of the
new commands. The command number field is a recognized extension
mechanism for TWAMP.
6.1. Registry Specification
IANA has created a TWAMP-Modes registry (as requested in [RFC5618]).
TWAMP-Modes are specified in TWAMP Server Greeting messages and
Set-up Response messages, as described in section 3.1 of [RFC5357],
consistent with section 3.1 of [RFC4656], and extended by this memo.
Modes are indicated by setting bits in the 32-bit Modes field. Thus,
this registry can contain a total of 32 possible values.
IANA has also created a TWAMP-Control Command Number registry.
TWAMP-Control commands are specified by the first octet in TWAMP-
Control messages as specified in section 3.5 of [RFC5357], and
augmented by this memo. This registry may contain 256 possible
values.
6.2. Registry Management
Because the TWAMP-Control Command Number registry can contain only
256 values and TWAMP-Modes can only contain thirty-two values, and
because TWAMP is an IETF protocol, these registries must be updated
only by "IETF Consensus" as specified in [RFC2434](an RFC documenting
registry use that is approved by the IESG). Management of these
Morton & Chiba Expires April 26, 2010 [Page 15]
Internet-Draft TWAMP Session Control October 2009
registries is described in section 8.2 of [RFC5357] and [RFC5618].
This memo proposes assignment of values 7, 8, 9 and 10 in the Command
number Registry, and the next available bit position (indicated by
"Z") and corresponding value (indicated by "zzz") in section 3.1
above. Note that these values should be replaced by IANA or the RFC
Editor when assigned.
6.3. Experimental Numbers
One experimental value has been assigned in the TWAMP-Control Command
Number registry.
No additional experimental values are assigned in the TWAMP-Modes
registry.
6.4. Registry Contents
TWAMP-Control Command Number Registry
Value Description Semantics Definition
0 Reserved
1 Forbidden
2 Start-Sessions RFC4656, Section 3.7
3 Stop-Sessions RFC4656, Section 3.8
4 Reserved
5 Request-TW-Session RFC5357, Section 3.5
6 Experimentation RFC5357, Section 8.3
------------------------------------------------------------------
7 Start-N-Sessions this memo, Section 3.2
8 Start-N-Ack this memo, Section 3.3
9 Stop-N-Sessions this memo, Section 3.4
10 Stop-N-Ack this memo, Section 3.5
TWAMP-Modes Registry
Morton & Chiba Expires April 26, 2010 [Page 16]
Internet-Draft TWAMP Session Control October 2009
Value Description Reference/Explanation
0 Reserved
1 Unauthenticated RFC4656, Section 3.1
2 Authenticated RFC4656, Section 3.1
4 Encrypted RFC4656, Section 3.1
8 Unauth. TEST protocol, draft-...-more-twamp (3)
Auth. CONTROL
--------------------------------------------------------
zzz Individual Session this memo, Section 3.1
Control bit position (Z)
The suggested values are:
Z=4 zzz=16
7. Acknowledgements
The author would like to thank anyone who provides valuable comments
on this feature.
8. References
8.1. Normative References
[I-D.ietf-ippm-twamp-reflect-octets]
Morton, A. and L. Ciavattone, "TWAMP Reflect Octets
Feature", draft-ietf-ippm-twamp-reflect-octets-02 (work in
progress), July 2009.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 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.
Morton & Chiba Expires April 26, 2010 [Page 17]
Internet-Draft TWAMP Session Control October 2009
8.2. Informative References
[x] "".
Authors' Addresses
Al Morton
AT&T Labs
200 Laurel Avenue South
Middletown,, NJ 07748
USA
Phone: +1 732 420 1571
Fax: +1 732 368 1192
Email: acmorton@att.com
URI: http://home.comcast.net/~acmacm/
Murtaza Chiba
Cisco Systems
170 W. Tasman Drive
San Jose, 95134
USA
Phone: +1 800 553 NETS
Fax: +1
Email: mchiba@cisco.com
URI:
Morton & Chiba Expires April 26, 2010 [Page 18]
