One document matched: draft-ietf-ippm-twamp-session-cntrl-07.xml
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<rfc category="std" docName="draft-ietf-ippm-twamp-session-cntrl-07"
ipr="pre5378Trust200902" updates="5357">
<front>
<title abbrev="TWAMP Session Control">Individual Session Control Feature
for TWAMP</title>
<author fullname="Al Morton" initials="A." surname="Morton">
<organization>AT&T Labs</organization>
<address>
<postal>
<street>200 Laurel Avenue South</street>
<city>Middletown,</city>
<region>NJ</region>
<code>07748</code>
<country>USA</country>
</postal>
<phone>+1 732 420 1571</phone>
<facsimile>+1 732 368 1192</facsimile>
<email>acmorton@att.com</email>
<uri>http://home.comcast.net/~acmacm/</uri>
</address>
</author>
<author fullname="Murtaza Chiba" initials="M." surname="Chiba">
<organization>Cisco Systems</organization>
<address>
<postal>
<street>170 W. Tasman Drive</street>
<city>San Jose</city>
<region></region>
<code>95134</code>
<country>USA</country>
</postal>
<phone>+1 800 553 NETS</phone>
<facsimile>+1</facsimile>
<email>mchiba@cisco.com</email>
<uri></uri>
</address>
</author>
<date day="8" month="April" year="2010" />
<abstract>
<t>The IETF has completed its work on the core specification of TWAMP -
the Two-Way Active Measurement Protocol. This memo describes an OPTIONAL
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.</t>
</abstract>
<note title="Requirements Language">
<t>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 <xref
target="RFC2119">RFC 2119</xref>.</t>
</note>
</front>
<middle>
<section title="Introduction">
<t>The IETF has completed its work on the core specification of TWAMP -
the Two-Way Active Measurement Protocol <xref target="RFC5357"></xref>.
TWAMP is an extension of the One-way Active Measurement Protocol, OWAMP
<xref target="RFC4656"></xref>. 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.</t>
<t>This memo describes an OPTIONAL feature for TWAMP. <xref
target="RFC5357"></xref> 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.</t>
<t>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.</t>
<t>The Individual Session Control feature gives the Control-Client new
flexibility to manage any number of test sessions once they are
established. However, <xref target="RFC5357"></xref> test sessions are
established in serial order and the total establishment time grows with
the number of sessions and the round-trip time. Therefore, implementers
of this feature may also wish to implement the "Reflect Octets" feature,
described in <xref target="I-D.ietf-ippm-twamp-reflect-octets"></xref>,
once it has been published as an RFC. This feature allows a
Control-Client to distinguish between parallel Request-TW-Session
commands, because a participating Server can return octets (e.g., the
Control-Client's local index) in its reply to the request. Thus, the
Reflect Octets feature supports the efficient establishment of many
simultaneous test sessions which the Individual Session Control feature
can then manage (start/stop).</t>
<t>This memo is an update to the TWAMP core protocol specified in <xref
target="RFC5357"></xref>. Measurement systems are not required to
implement the feature described in this memo to claim compliance with
<xref target="RFC5357"></xref>.</t>
<t>Throughout this memo, the bits marked MBZ (Must Be Zero) MUST be set
to zero by senders and MUST be ignored by receivers. Also, the HMAC
(Hashed Message Authentication Code) MUST be calculated as defined in
Section 3.2 of <xref target="RFC4656"></xref>.</t>
</section>
<section title="Purpose and Scope">
<t>The purpose of this memo is to describe an additional OPTIONAL
function and feature for TWAMP <xref target="RFC5357"></xref>.</t>
<t>The scope of the memo is limited to specifications of the following
features:</t>
<t><list style="numbers">
<t>Extension of the modes of operation through assignment of a new
value in the Mode field to communicate feature capability and
use,</t>
<t>the definitions of augmented start session and stop session
commands (with corresponding acknowledgements), and</t>
<t>the definition of related procedures for TWAMP entities.</t>
</list>The motivation for this feature is the ability to start and
stop individual test sessions at will, using a single TWAMP-control
connection.</t>
<t>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.</t>
</section>
<section title="TWAMP Control Extensions">
<t>TWAMP-Control protocol is a derivative of the OWAMP-Control protocol,
and provides two-way measurement capability. TWAMP <xref
target="RFC5357"></xref> 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.</t>
<section title="Connection Setup with Individual Session Control">
<t>TWAMP-Control connection establishment follows the procedure
defined in section 3.1 of <xref target="RFC4656"></xref> 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:</t>
<t><figure>
<preamble></preamble>
<artwork><![CDATA[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, RFC5618, Section 3.1
Auth. CONTROL
--------------------------------------------------------
zzz Individual Session this memo, bit position (Z)
Control
]]></artwork>
<postamble></postamble>
</figure></t>
<t>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 <xref
target="RFC4656"></xref>). In the <xref target="RFC5618"></xref> memo,
bit position (3) allows a different security mode in the Test protocol
and uses the unauthenticated test packet format.</t>
<t>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.</t>
<t>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:<list style="numbers">
<t>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.</t>
<t>The Control-Client and the Server MUST NOT use the start and
stop commands (2 and 3) and the acknowledgement defined in <xref
target="RFC5357"></xref>.</t>
</list></t>
<t>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).</t>
</section>
<section title="Start-N-Sessions Command with Individual Session Control">
<t>Having</t>
<t><list style="symbols">
<t>initiated Individual Session Control mode in the Setup
Response,</t>
<t>requested one or more test sessions, and</t>
<t>received affirmative Accept-Session response(s),</t>
</list>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).</t>
<t>The format of the Start-N-Sessions message is as follows:</t>
<t><figure>
<preamble></preamble>
<artwork><![CDATA[ 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]]></artwork>
<postamble></postamble>
</figure></t>
<t>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.</t>
<t>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).</t>
<t>All SID fields are constructed as defined in the last paragraph of
OWAMP section 3.5 <xref target="RFC4656"></xref> (and referenced in
TWAMP). Note that the SID is assigned by the Server during the session
request exchange.</t>
<t>The message is terminated with a single block HMAC, as illustrated
above.</t>
<t>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.</t>
<t>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.</t>
</section>
<section title="Start-N-Ack Command with Individual Session Control">
<t>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 of the sessions referenced in a
particular Start-N-Sessions command, but can start one or more of the
sessions.</t>
<t>The format of the message is as follows.</t>
<t><figure>
<preamble></preamble>
<artwork><![CDATA[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) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>
<postamble></postamble>
</figure></t>
<t>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.</t>
<t>The Accept Field values are defined in OWAMP section 3.3 <xref
target="RFC4656"></xref>.</t>
<t>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.</t>
<t>All SID fields are constructed as defined in the last paragraph of
OWAMP section 3.5 <xref target="RFC4656"></xref> (and referenced in
TWAMP). Note that the SID is assigned by the Server during the session
request exchange.</t>
<t>The message is terminated with a single block HMAC, as illustrated
above.</t>
<t>Note that the SIDs for all Sessions with the same 'Accept' code can
be acknowledged using the same Start-N-Ack message.</t>
<t>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:</t>
<t>Accept = 0 Number of Sessions = 3 SIDs 1, 2, 4</t>
<t>Accept = 5 Number of Sessions = 1 SID 3</t>
</section>
<section title="Stop-N-Sessions Command with Individual Session Control">
<t>The Stop-N-Sessions command can only be issued by the
Control-Client. The command MUST contain at least one SID.</t>
<t>The TWAMP Stop-N-Sessions command for use in Individual Session
Control mode is formatted as follows:</t>
<t><figure>
<preamble></preamble>
<artwork><![CDATA[ 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
]]></artwork>
<postamble></postamble>
</figure></t>
<t>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.</t>
<t>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 <xref target="RFC4656"></xref> 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.</t>
<t>The message is terminated with a single block HMAC, as illustrated
above.</t>
<t>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.</t>
</section>
<section title="Stop-N-Ack Command with Individual Session Control">
<t>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 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 of the sessions referenced
in a particular Stop-N-Sessions command, but can stop one or more of
the sessions.</t>
<t>The format for the Stop-N-Ack command is as follows:</t>
<t><figure>
<preamble></preamble>
<artwork><![CDATA[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) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>
<postamble></postamble>
</figure></t>
<t>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.</t>
<t>The Accept Field values are defined in OWAMP section 3.3 <xref
target="RFC4656"></xref>.</t>
<t>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.</t>
<t>All SID fields are constructed as defined in the last paragraph of
OWAMP section 3.5 <xref target="RFC4656"></xref> (and referenced in
TWAMP). Note that the SID is assigned by the Server during the session
request exchange.</t>
<t>The message is terminated with a single block HMAC, as illustrated
above.</t>
<t>Note that the SIDs for all Sessions with the same 'Accept' code can
be acknowledged using the same Stop-N-Ack message.</t>
</section>
<section title="SERVWAIT Timeout Operation">
<t>Section 3.1 of <xref target="RFC5357"></xref> 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.</t>
<t>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.</t>
<t>The diagram below illustrates the operation of timers SERVWAIT and
REFWAIT.</t>
<t><figure>
<preamble></preamble>
<artwork><![CDATA[ SERVWAIT REFWAIT SERVWAIT
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+
(no sessions
in-progress)
+-+-+-+-+-+-+-+-+-+-+-+
SID="1"
+-+-+-+-+
SID="2"
+-+-+-+-+-+-+-+-+
SID="3"
>>>>>>>>>> Time >>>>>>>>>>>>>>>>>>> Time >>>>>>>>>>>>>>>> Time >>>>>
]]></artwork>
<postamble></postamble>
</figure></t>
</section>
<section title="Additional considerations">
<t>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.</t>
<t>With the publication of this feature, bit positions 0 through (Z=4)
of the Modes 32-bit field are used. A Control-Client MAY ignore bit
positions greater than 2 in the Modes Field, or it MAY support
OPTIONAL features that are communicated in bit positions 3 and higher.
(The unassigned bits are available for future protocol
extensions.)</t>
<t>Other ways in which TWAMP extends OWAMP are described in <xref
target="RFC5357"></xref>.</t>
</section>
</section>
<section title="TWAMP Test with Individual Session Control">
<t>The TWAMP test protocol is similar to the OWAMP <xref
target="RFC4656"></xref> 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 <xref
target="RFC5357"></xref> 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.</t>
<section title="Sender Behavior">
<t>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 <xref
target="RFC5357"></xref>.</t>
</section>
<section title="Reflector Behavior">
<t>The TWAMP Reflector follows the procedures and guidelines in
section 4.2 of <xref target="RFC5357"></xref>, with the following
additional functions required by this feature:</t>
<t><list style="symbols">
<t>The Session-Reflector MUST manage all test sessions accepted
according to their SID.</t>
<t>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 for packets that are ignored. (Note: The
Request-TW-Session command includes sender address + port and
receiver address + port, and this is usually sufficient to
distinguish sessions.)</t>
<t>If the REFWAIT timer is implemented, it SHOULD be enforced when
any test session is in-progress (started and not stopped).</t>
</list></t>
</section>
</section>
<section anchor="Security" title="Security Considerations">
<t>The security considerations that apply to any active measurement of
live networks are relevant here as well. See the security considerations
in<xref target="RFC4656"></xref> and <xref target="RFC5357"></xref>.</t>
</section>
<section anchor="IANA" title="IANA Considerations">
<t>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.</t>
<t>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.</t>
<section title="Registry Specification">
<t>IANA has created a TWAMP-Modes registry (as requested in <xref
target="RFC5618"></xref>). TWAMP-Modes are specified in TWAMP Server
Greeting messages and Set-up Response messages, as described in
section 3.1 of <xref target="RFC5357"></xref>, consistent with section
3.1 of <xref target="RFC4656"></xref>, and extended by this memo.
Modes are indicated by setting bits in the 32-bit Modes field that
correspond to values in the Modes registry. For the TWAMP-Modes
registry, we expect that new features will be assigned increasing
registry values that correspond to single bit positions, unless there
is a good reason to do otherwise (more complex encoding than single
bit positions may be used in the future, to access the 2^32 value
space).</t>
<t>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 <xref
target="RFC5357"></xref>, and augmented by this memo. This registry
may contain 256 possible values.</t>
</section>
<section title="Registry Management">
<t>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 <xref
target="RFC5226"></xref> (an RFC documenting registry use that is
approved by the IESG). Management of these registries is described in
section 8.2 of <xref target="RFC5357"></xref> and <xref
target="RFC5618"></xref>.</t>
<t>This memo proposes assignment of values 7, 8, 9 and 10 in the
Command number Registry, and a Mode registry value (indicated by
"zzz") corresponding to the next available bit position (indicated by
"Z") in sections 3.1 and 3.7 above. Note that the "zzz" and "Z"
strings should be replaced by IANA or the RFC Editor when values are
assigned.</t>
</section>
<section title="Experimental Numbers">
<t>One experimental value has been assigned in the TWAMP-Control
Command Number registry.</t>
<t>No additional experimental values are assigned in the TWAMP-Modes
registry.</t>
</section>
<section title="Registry Contents">
<t>TWAMP-Control Command Number Registry<figure>
<preamble></preamble>
<artwork><![CDATA[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
]]></artwork>
<postamble></postamble>
</figure></t>
<t>TWAMP-Modes Registry<figure>
<preamble></preamble>
<artwork><![CDATA[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, RFC5618, Section 3.1
Auth. CONTROL
--------------------------------------------------------
zzz Individual Session this memo, Section 3.1
Control bit position (Z)]]></artwork>
<postamble></postamble>
</figure>The suggested values are:</t>
<t>The next value corresponding to an unused bit is zzz=16, with
Z=4.</t>
</section>
</section>
<section anchor="Acknowledgements" title="Acknowledgements">
<t>The authors thank everyone who provided comments on this feature,
especially Lars Eggert, Adrian Farrel, and Alexey Melnikov.</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include="reference.RFC.2119"?>
<?rfc include='reference.RFC.4656'?>
<?rfc include='reference.RFC.5357'?>
<?rfc include='reference.RFC.5226'?>
<?rfc include='reference.RFC.5618'?>
<?rfc ?>
<?rfc ?>
<?rfc ?>
</references>
<references title="Informative References">
<?rfc ?>
<?rfc include='reference.I-D.ietf-ippm-twamp-reflect-octets'?>
</references>
</back>
</rfc>| PAFTECH AB 2003-2026 | 2026-04-24 12:22:53 |