One document matched: draft-ietf-dccp-udpencap-06.xml
<?xml version="1.0" encoding="US-ASCII"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd">
<rfc category="std" docName="draft-ietf-dccp-udpencap-06" ipr="trust200902">
updates="5762">
<!-- Updates SDP -->
<?rfc toc="yes"?>
<!-- generate a table of contents -->
<?rfc symrefs="yes"?>
<!-- use anchors instead of numbers for references -->
<?rfc sortrefs="yes" ?>
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<?rfc compact="yes" ?>
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<?rfc subcompact="no" ?>
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<front>
<title abbrev="DCCP-UDP Encapsulation">Datagram Congestion Control
Protocol (DCCP) Encapsulation for NAT Traversal (DCCP-UDP)</title>
<author fullname="Tom Phelan" initials="T." surname="Phelan">
<organization abbrev="Sonus">Sonus Networks</organization>
<address>
<postal>
<street>7 Technology Dr.</street>
<city>Westford</city>
<region>MA</region>
<code>01886</code>
<country>US</country>
</postal>
<phone>+1 978 614 8456</phone>
<email>tphelan@sonusnet.com</email>
</address>
</author>
<author fullname="Godred Fairhurst" initials="G." surname="Fairhurst">
<organization>University of Aberdeen</organization>
<address>
<postal>
<street>School of Engineering</street>
<street>Fraser Noble Building</street>
<city>Aberdeen</city>
<region>Scotland</region>
<code>AB24 3UE</code>
<country>UK</country>
</postal>
<email>gorry@erg.abdn.ac.uk</email>
<uri>http://www.erg.abdn.ac.uk</uri>
</address>
</author>
<date day="25" month="February" year="2011" />
<area>Transport</area>
<workgroup>DCCP Working Group</workgroup>
<keyword>DCCP</keyword>
<keyword>NAPT</keyword>
<keyword>NAT</keyword>
<keyword>UDP</keyword>
<abstract>
<t>This document specifies an alternative encapsulation of the Datagram
Congestion Control Protocol (DCCP), referred to as DCCP-UDP. This
encapsulation allows DCCP to be carried through the current generation
of Network Address Translation (NAT) middleboxes without modification of
those middleboxes. This document also updates the SDP information for
DCCP defined in RFC 5762.</t>
</abstract>
</front>
<middle>
<!-- text starts here -->
<section title="Introduction" toc="include">
<t>The Datagram Congestion Control Protocol (DCCP), specified in <xref
target="RFC4340" />, is a transport-layer protocol that provides upper
layers with the ability to use non-reliable congestion-controlled flows.
The current specification for DCCP <xref target="RFC4340" /> specifies a
direct encapsulation in IPv4 or IPv6 packets.</t>
<t><xref target="RFC5597" /> specifies how DCCP should be handled by
devices that use Network Address Translation (NAT) or Network Address
and Port Translation (NAPT). However, there is a significant installed
base of NAT/NAPT devices that do not support <xref target="RFC5597" />.
In the short term, it would be useful to have an encapsulation for DCCP
that is compatible with this installed base of NAT/NAPT devices that
support <xref target="RFC4787" />, but do not support <xref
target="RFC5597" />. This document specifies that encapsulation, which
is referred to as DCCP-UDP. For convenience, the standard encapsulation
for DCCP <xref target="RFC4340" /> (including <xref target="RFC5596" />
as required) is referred to as DCCP-STD.</t>
<t>The document also updates the SDP specification for DCCP to convey
the encapsulation type. In this respect only, it updates the method in
<xref target="RFC5762" />.</t>
<t>The DCCP-UDP encapsulation specified in this document supports all of
the features contained in DCCP-STD, but with limited functionality for
partial checksums.</t>
</section>
<section title="Terminology" toc="include">
<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" />.</t>
</section>
<section title="DCCP-UDP" toc="include">
<t>The basic approach is to insert a UDP <xref target="RFC0768" />
header between the IP header and the DCCP packet. Note that this is not
a tunneling approach. The IP addresses of the communicating end systems
are carried in the IP header. The method does not embed additional IP
addresses.</t>
<t>The method is designed to support use when these addresses are
modified by a device that implements NAT/NAPT. A NAT translates the IP
addresses, which impacts the transport-layer checksum. A NAPT device may
also translate the port values (usually the source port). In both cases,
the outer transport header that includes these values would need to be
updated by the NAT/NAPT.</t>
<t>A device offering or using DCCP services via DCCP-UDP encapsulation
listens on a UDP port (default port, XXX IANA PORT XXX), or may bind to
a specified port utilising out-of-band signalling, such as the Session
Description Protocol (SDP). The DCCP-UDP server accepts incoming packets
over the UDP transport and passes the received packets to the DCCP
protocol module, after removing the UDP encapsulation.</t>
<t>A DCCP implementation MAY allow services to be simultaneously offered
over any or all combinations of DCCP-STD and DCCP-UDP encapsulations
with IPv4 and IPv6.</t>
<t>The basic format of a DCCP-UDP packet is:</t>
<figure>
<artwork><![CDATA[
+-----------------------------------+
| IP Header (IPv4 or IPv6) | Variable length
+-----------------------------------+
| UDP Header | 8 bytes
+-----------------------------------+
| DCCP Generic Header | 12 or 16 bytes
+-----------------------------------+
| Additional (type-specific) Fields | Variable length (could be 0)
+-----------------------------------+
| DCCP Options | Variable length (could be 0)
+-----------------------------------+
| Application Data Area | Variable length (could be 0)
+-----------------------------------+
]]></artwork>
</figure>
<section title="The UDP Header" toc="include">
<t>The format of the UDP header is specified in <xref
target="RFC0768" />:</t>
<figure>
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port | Dest Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
</figure>
<t>For DCCP-UDP, the fields are interpreted as follows:</t>
<t>Source and Dest(ination) Ports: 16 bits each</t>
<t>
<list style="empty">
<t>These fields identify the UDP ports on which the source and
destination (respectively) of the packet are listening for
incoming DCCP-UDP packets. The UDP port values do not identify the
DCCP source and destination ports.</t>
</list>
</t>
<t>Length: 16 bits</t>
<t>
<list style="empty">
<t>This field is the length of the UDP datagram, including the UDP
header and the payload (for DCCP-UDP, the payload is a DCCP-UDP
datagram).</t>
</list>
</t>
<t>Checksum: 16 bits</t>
<t>
<list style="empty">
<t>This field is the Internet checksum of a network-layer
pseudoheader and Length bytes of the UDP packet [RFC0768]. The UDP
checksum MUST NOT be zero for a UDP packet that carries
DCCP-UDP.</t>
</list>
</t>
</section>
<section title="The DCCP Generic Header" toc="include">
<t>The DCCP Generic Header <xref target="RFC4340" /> takes two forms,
one with long sequence numbers (48 bits) and the other with short
sequence numbers (24 bits).</t>
<figure>
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port | Dest Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Offset | CCVal | CsCov | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |X| | .
| Res | Type |=| Reserved | Sequence Number (high bits) .
| | |1| | .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number (low bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
</figure>
<t>The Generic DCCP Header with long sequence numbers <xref
target="RFC4340" /></t>
<figure>
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port | Dest Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Offset | CCVal | CsCov | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |X| |
| Res | Type |=| Sequence Number (low bits) |
| | |0| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
</figure>
<t>The Generic DCCP Header with short sequence numbers <xref
target="RFC4340" /></t>
<t>All generic header fields, except for the Checksum field, have the
meaning specified in <xref target="RFC4340" /> updated by <xref
target="RFC5596" />.</t>
<t>Section 3.8 describes how a DCCP-UDP implementation treats UDP and
DCCP ports.</t>
</section>
<section title="DCCP-UDP Checksum Procedures" toc="include">
<t>DCCP-UDP employs a checksum at the UDP level and eliminates the use
of the DCCP checksum. This approach was chosen to enable use of
current NAT/NATP traversal methods developed for UDP. Such methods
will generally be unaware whether DCCP is being encapsulated and hence
do not update the inner checksum in the DCCP header. Standard DCCP
requires protection of the DCCP header fields, this justifies any
processing overhead incurred from calculating the UDP checksum.</t>
<t>In addition, UDP NAT traversal does not support partial checksums.
Although this is still permitted end-to-end in the encapsulated DCCP
datagram, links along the path will treat these as UDP packets and can
not enable special partial checksum processing.</t>
<t>For DCCP-UDP, the function of the DCCP Checksum field is performed
by the UDP checksum field. On transmit, the DCCP Checksum field SHOULD
be set to zero. On receive, the DCCP Checksum field MUST be
ignored.</t>
<t>The UDP checksum MUST NOT be zero for a UDP packet that is sent
using DCCP-UDP. If the received UDP Checksum field is zero, the packet
MUST be dropped.</t>
<t>If the UDP Length field is less than 20 (the UDP Header length and
minimum DCCP-UDP header length), the packet MUST be dropped.</t>
<t>If the UDP Checksum field, computed using standard UDP methods, is
invalid, the packet MUST be dropped.</t>
<t>If the UDP Length field in a received packet is less than the
length of the UDP header plus the entire DCCP-UDP header (including
the generic header and type-specific fields and options, if present),
or the UDP Length field is greater than the length of the packet from
the beginning of the UDP header to the end of the packet, the packet
MUST be dropped.</t>
<section title="Partial Checksums and the Minimum Checksum Coverage Feature"
toc="include">
<t>DCCP-UDP supports the syntax of partial checksums. It also
supports negotiation of the Minimum Checksum Coverage feature and
settings of the CsCov field. However, the UDP checksum field in
DCCP-UDP always covers the entire DCCP datagram and the DCCP
checksum is ignored on receipt. An application that enables this
feature will experience a service that is functionally identical to
using full checksum coverage. This is also the service that the
application would have received if it had used a network path that
did not provide optimised processing for DCCP partial checksums.</t>
</section>
</section>
<section title="Network Layer Options" toc="include">
<t>A DCCP-UDP implementations MAY transfer network-layer options
intended for DCCP to the network-layer header of the encapsulating UDP
packet.</t>
<t>A DCCP-UDP endpoint that receives IP-options for the encapsulating
UDP packet MAY forward these to the DCCP protocol module. If the
endpoint forwards a specific network layer option to the DCCP module,
it MUST also forward all subsequent packets with this option.
Consistent forwarding is essential for correct operation of many
end-to-end options.</t>
</section>
<section title="Explicit Congestion Notification" toc="default">
<t>A DCCP-UDP endpoint SHOULD follow the procedures of DCCP-STD
section 12 by setting the ECN fields in the IP Headers of outgoing
packets and examining the values received in the ECN fields of
incoming IP packets, relaying any packet markings to the DCCP
module.</t>
<t>Implementations that do not support ECN MUST follow the procedures
in DCCP-STD section 12.1 with regard to implementations that are not
ECN capable.</t>
</section>
<section title="ICMP handling for messages relating to DCCP-UDP"
toc="include">
<t>To allow ICMP messages to be demultiplexed by the receiving
endpoint, part of the original packet that resulted in the message is
included in the payload of the ICMP error message. The receiving
endpoint can therefore use this information to associate the ICMP
error with the transport protocol instance that resulted in the ICMP
message. When DCCP-UDP is used, the error message and the payload of
the ICMP error message relate to the UDP transport.</t>
<t>DCCP-UDP endpoints SHOULD forward ICMP messages relating to a UDP
packet that carries a DCCP-UDP to the DCCP module. This may imply
translation of the payload of the ICMP message into a form that is
recognised by the DCCP stack. <xref target="ICMP" /> describes
precautions that are desirable before TCP acts on the receipt of an
ICMP message. Similar precautions are desirable prior to forwarding by
DCCP-UDP to the DCCP module.</t>
</section>
<section title="Path Maximum Transmission Unit Discovery" toc="include">
<t>DCCP-UDP implementations SHOULD follow DCCP-STD section 14 with
regard to determining the maximum packet size and the use of Path
Maximum Transmission Unit Discovery (PMTUD).</t>
</section>
<section anchor="port" title="Usage of the UDP port by DCCP-UDP"
toc="include">
<t>A DCCP-UDP server (that is, an initially passive endpoint that
wishes to receive DCCP-Request packets [RFC4340] over DCCP-UDP)
listens for connections on one or more UDP ports. UDP port number XXX
IANA PORT XXX has been reserved as the default listening UDP port for
DCCP-UDP connections. Some NAT/NAPT topologies may require using a
non-default listening port.</t>
<t>A DCCP-UDP client provides UDP source and destination ports as well
as DCCP source and destination ports at connection initiation time. A
client SHOULD ensure that each DCCP connection maps to a single UDP
connection by setting the UDP source port. Choosing a distinct source
UDP port for each distinct DCCP connection ensures that UDP-based flow
identifiers differ whenever DCCP-based flow identifiers differ.
Specifically, two connections with different <source IP address,
source DCCP port, destination IP address, destination DCCP port>
DCCP 4-tuples will have different <source IP address, source UDP
port, destination IP address, destination UDP port> UDP
4-tuples.</t>
<t>A DCCP-UDP server SHOULD accept datagrams from any UDP source port.
There is a risk that the same DCCP source port number could be used by
two endpoints each behind a NAPT. A DCCP-UDP server must therefore
demultiplex a DCCP-UDP flow using both the UDP source and destination
port numbers and the encapsulated DCCP ports. This ensures than an
active DCCP connection is uniquely identified by the 6-tuple
<source IP address, source UDP port, source DCCP port, destination
IP address, destination UDP port, destination DCCP port>.</t>
<t>The demultiplexing at a DCCP-UDP endpoint occurs in two stages:</t>
<t>1) In the first stage, DCCP-UDP packets are demultiplexed using the
UDP 4-tuple: <source IP address, source UDP port, destination IP
address, destination UDP port>.</t>
<t>2) In the second stage, a receiving endpoint MUST ensure that two
independent DCCP connections that were multiplexed to the same UDP
4-tuple are not associated with the same connection in the DCCP
module. The endpoint therefore needs to keep state for the set of
active DCCP-UDP endpoints using each combination of a UDP 4-tuple:
<source IP address, source UDP port, destination IP address,
destination UDP port>. A DCCP endpoint MUST implement one of the
two methods:</t>
<t>
<list style="symbols">
<t>A DCCP server MAY accept only one active 6-tuple at any one
time for a given UDP 4-tuple. In this method, DCCP-UDP packets
that do not match an active 6-tuple MUST NOT be passed to the DCCP
module and the DCCP Server SHOULD send a DCCP-Reset with with
Reset Code XXX IANA Port Reuse XXX, "Encapsulated Port Reuse". An
endpoint that receives a DCCP-Reset with this reset code MAY
immediately try again using a different 4-tuple. This provides
protection should the same UDP 4-tuple be re-used by multiple DCCP
connections, ensuring that only one DCCP connection is established
at one time.</t>
<t>A DCCP server MAY support multiple DCCP connections over the
same UDP 4-tuple. In this method, the endpoint MUST then associate
each 6-tuple with a single DCCP connection. If an endpoint is
unable to demultiplex the 6-tuple (e.g. due to internal resource
limits), it MUST NOT pass DCCP-UDP packets that do not match an
active 6-tuple to the DCCP module. The DCCP endpoint MAY send a
DCCP-Reset with Reset Code XXX IANA Port Reuse XXX, "Encapsulated
Port Reuse", indicating the connection may be retried using a
different UDP 4-tuple.</t>
</list>
</t>
</section>
<section title="Service Codes and the DCCP Port Registry" toc="include">
<t>This section clarifies the usage of DCCP Service Codes and the
registration of server ports by DCCP-UDP. The section is not intended
to update the procedures for allocating Service Codes or server
ports.</t>
<t>There is one Service Code registry and one DCCP port registration
that apply to all combinations of encapsulation and IP version. A DCCP
Service Code specifies an application using DCCP regardless of the
combination of DCCP encapsulation and IP version. An application may
choose not to support some combinations of encapsulation and IP
version, but its Service Code will remain registered for those
combinations and the Service Code must not be used by other
applications. An application should not register different Service
Codes for different combinations of encapsulation and IP version.
<xref target="RFC5595" /> provides additional information about DCCP
Service Codes.</t>
<t>Similarly, a port registration is applicable to all combinations of
encapsulation and IP version. Again, an application may choose not to
support some combinations of encapsulation and IP version on its
registered port, although the port will remain registered for those
combinations. Applications should not register different ports just
for the purpose of using different combinations of encapsulation.</t>
</section>
</section>
<section title="DCCP-UDP and Higher-Layer Protocols" toc="include">
<t>The encapsulation of a higher-layer protocol within DCCP MUST be the
same for both DCCP-STD and DCCP-UDP. Encapsulations of DTLS over DCCP is
defined in <xref target="RFC5238" /> and RTP over DCCP is defined in
<xref target="RFC5762" />. This document therefore does not update these
encapsulations when using DCCP-UDP.</t>
</section>
<section title="Signaling the Use of DCCP-UDP" toc="exclude">
<t>Applications often signal transport connection parameters through
outside means, such as SDP. Applications that define such methods for
DCCP MUST define how the DCCP encapsulation is chosen, and MUST allow
either encapsulation to be signaled.</t>
<t>Procedures for handling DCCP-STD and/or DCCP-UDP with Interactive
Connectivity Establishment (ICE) may need to be developed, but are left
for further work.</t>
<section anchor="sdp" title="SDP support for DCCP-UDP" toc="include">
<t><xref target="RFC5762" /> defines SDP extensions for signaling RTP
over DCCP connections. Since it predates this document, it does not
define a method for determining the DCCP encapsulation type. This
document updates <xref target="RFC5762" /> to add a method for
determining the DCCP encapsulation type.</t>
<t>A new SDP attribute "dccp-encap" is defined for signaling the DCCP
encapsulation according to the following ABNF <xref
target="RFC5234" />:</t>
<figure>
<artwork><![CDATA[
dccp-encap-attr = %x61 "=dccp-in-udp" [":" udp-port-num]
udp-port-num = *DIGIT
]]></artwork>
</figure>
<t>where *DIGIT is as defined in <xref target="RFC5234" />.</t>
<t>The presence of "a=dccp-in-udp" in an SDP offer indicates that the
offerer is listening for DCCP-UDP connections on the indicated UDP
port (if udp-port-num is included) or on the default port for the
DCCP-UDP service if no port is included. This attribute MAY also be
used in a declarative SDP file.</t>
<t>The absence of "a=dccp-in-udp" in an SDP offer indicates that the
offerer is listening for DCCP-STD connections. The presence of
"a=dccp-in-udp" conveys no information about whether or not the
offerer is listening for DCCP-STD connections.</t>
<t>The new SDP attribute specified in this section is expected to be
useful when the offering party is on the public Internet, or in the
same private addressing realm as the answering party. Some other
NAT/NAPT topologies may result in the advertised port being
unreachable via the NAT/NAPT.</t>
</section>
</section>
<section title="Security Considerations" toc="include">
<t>DCCP-UDP provides all of the security risk-mitigation measures
present in DCCP-STD, and also all of the security risks.</t>
<t>The purpose of DCCP-UDP is to allow DCCP to pass through NAT/NAPT
devices, and therefore it exposes DCCP to the risks associated with
passing through NAT devices. It does not create any new risks with
regard to NAT/NAPT devices.</t>
<t>The tunnel encapsulation recommends processing of ICMP messages
received for packets sent using DCCP-UDP and translation to allow use by
DCCP. <xref target="ICMP" /> describes precautions that are desirable
before TCP acts on receipt of ICMP messages. Similar precautions are
desirable for endpoints processing ICMP for DCCP-UDP.</t>
<t>DCCP-UDP may also allow DCCP applications to pass through existing
firewall devices, if the administrators of the devices so choose. A
simple use may either allow all DCCP applications or allow none.</t>
<t>A firewall than interprets this specification could inspect the
encapsualted DCCP header to filter based on DCCP information. Full
control of DCCP connections by application will require enhancements to
firewalls, as discussed in <xref target="RFC4340" /> and related RFCs
(e.g. <xref target="RFC5595" />).</t>
</section>
<section title="IANA Considerations" toc="include">
<t>This document requests IANA to make the allocations described in the
following sections.</t>
<section title=" UDP Port Allocation">
<t>IANA is requested to allocate a UDP port for the dccp-udp service.
Use of this port is defined in section <xref target="port" /></t>
<t>XXX Note: IANA is requested to replace all occurrences of "XXX IANA
PORT XXX" by the allocated port value prior to publication. XXX</t>
</section>
<section title="DCCP Reset">
<t>IANA is requested to assign a new DCCP Reset Code in the DCCP Reset
Codes Registry, with the short description "Encapsulated Port Reuse".
This code applies to all DCCP congestion control IDs and should be
allocated a value less than 120 decimal. Use of this reset code is
defined in section <xref target="port" /></t>
<t>. Section 5.6 of RFC4340 defines three "Data" bytes that are
carried by a DCCP Reset. For this Reset Code these are defined as
below:</t>
<t>
<list style="symbols">
<t>Data byte 1: The DCCP Packet Type of the datagram that resulted
in the error message.</t>
<t>Data byte 2 & 3: The encapsulated Source UDP Port, in
network order</t>
</list>
</t>
<t>XXX Note: IANA is requested to replace all occurrences of "XXX IANA
Port Reuse XXX" by the allocated DCCP reset code value prior to
publication. XXX</t>
</section>
<section title="SDP Attribute Allocation">
<t>IANA is requested to allocate the following new SDP attribute
("att-field"):<list style="empty">
<t>Contact name: DCCP Working Group</t>
<t>Attribute name: dccp-in-udp</t>
<t>Long-form attribute name in English: DCCP in UDP
Encapsulation</t>
<t>Type of attribute: Media level</t>
<t>Subject to charset attribute? No</t>
<t>Purpose of the attribute: See this document section <xref
target="sdp" /></t>
<t>Allowed attribute values: See this document section <xref
target="sdp" /></t>
</list></t>
</section>
</section>
<section title="Acknowledgments">
<t>This document was produced by the DCCP WG. The following contributed
during the working group last call:</t>
<t>Andrew Lentvorski, Lloyd Wood, Pasi Sarolahti, Gerrit Renker, Eddie
Kohler, Colin Perkins, Gorry Fairhurst and Tom Phelan.</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc sortrefs="yes"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.4340.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.0768.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.5234.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.5762.xml"?>
</references>
<references title="Informative References">
<?rfc sortrefs="yes"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.4787.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.5238.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.5595.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.5596.xml"?>
<?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.5597.xml"?>
<reference anchor="ICMP">
<front>
<title>"ICMP attacks against TCP", IETF Work-in-Progress.</title>
<author fullname="F." surname="Gont">
<organization>Internet draft,
draft-gont-tcpm-icmp-attacks-05.txt</organization>
</author>
</front>
</reference>
</references>
</back>
</rfc>
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