draft-ietf-dccp-udpencap-10.txt   draft-ietf-dccp-udpencap-11.txt 
DCCP Working Group T. Phelan DCCP Working Group T. Phelan
Internet-Draft Sonus Internet-Draft Sonus
Intended status: Standards Track G. Fairhurst Intended status: Standards Track G. Fairhurst
Expires: September 27, 2012 University of Aberdeen Expires: December 27, 2012 University of Aberdeen
C. Perkins C. Perkins
University of Glasgow University of Glasgow
March 26, 2012 June 25, 2012
Datagram Congestion Control Protocol (DCCP) Encapsulation for NAT Datagram Congestion Control Protocol (DCCP) Encapsulation for NAT
Traversal (DCCP-UDP) Traversal (DCCP-UDP)
draft-ietf-dccp-udpencap-10 draft-ietf-dccp-udpencap-11
Abstract Abstract
This document specifies an alternative encapsulation of the Datagram This document specifies an alternative encapsulation of the Datagram
Congestion Control Protocol (DCCP), referred to as DCCP-UDP. This Congestion Control Protocol (DCCP), referred to as DCCP-UDP. This
encapsulation allows DCCP to be carried through the current encapsulation allows DCCP to be carried through the current
generation of Network Address Translation (NAT) middleboxes without generation of Network Address Translation (NAT) middleboxes without
modification of those middleboxes. This document also updates the modification of those middleboxes. This document also updates the
SDP information for DCCP defined in RFC 5762. SDP information for DCCP defined in RFC 5762.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 27, 2012. This Internet-Draft will expire on December 27, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. DCCP-UDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. DCCP-UDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. The UDP Header . . . . . . . . . . . . . . . . . . . . . . 4 3.1. The UDP Header . . . . . . . . . . . . . . . . . . . . . . 5
3.2. The DCCP Generic Header . . . . . . . . . . . . . . . . . 5 3.2. The DCCP Generic Header . . . . . . . . . . . . . . . . . 5
3.3. DCCP-UDP Checksum Procedures . . . . . . . . . . . . . . . 6 3.3. DCCP-UDP Checksum Procedures . . . . . . . . . . . . . . . 6
3.3.1. Partial Checksums and the Minimum Checksum 3.3.1. Partial Checksums and the Minimum Checksum
Coverage Feature . . . . . . . . . . . . . . . . . . . 7 Coverage Feature . . . . . . . . . . . . . . . . . . . 7
3.4. Network Layer Options . . . . . . . . . . . . . . . . . . 7 3.4. Network Layer Options . . . . . . . . . . . . . . . . . . 8
3.5. Explicit Congestion Notification . . . . . . . . . . . . . 7 3.5. Explicit Congestion Notification . . . . . . . . . . . . . 8
3.6. ICMP handling for messages relating to DCCP-UDP . . . . . 8 3.6. ICMP handling for messages relating to DCCP-UDP . . . . . 8
3.7. Path Maximum Transmission Unit Discovery . . . . . . . . . 8 3.7. Path Maximum Transmission Unit Discovery . . . . . . . . . 9
3.8. Usage of the UDP port by DCCP-UDP . . . . . . . . . . . . 8 3.8. Usage of the UDP port by DCCP-UDP . . . . . . . . . . . . 9
3.9. Service Codes and the DCCP Port Registry . . . . . . . . . 10 3.9. Service Codes and the DCCP Port Registry . . . . . . . . . 11
4. DCCP-UDP and Higher-Layer Protocols . . . . . . . . . . . . . 10 4. DCCP-UDP and Higher-Layer Protocols . . . . . . . . . . . . . 11
5.1. Protocol Identification . . . . . . . . . . . . . . . . . 11 5.1. Protocol Identification . . . . . . . . . . . . . . . . . 12
5.2. Signalling Encapsulated DCCP Ports . . . . . . . . . . . . 12 5.2. Signalling Encapsulated DCCP Ports . . . . . . . . . . . . 13
5.3. Connection Management . . . . . . . . . . . . . . . . . . 13 5.3. Connection Management . . . . . . . . . . . . . . . . . . 14
5.4. Negotiating the DCCP-UDP encapsulation versus native 5.4. Negotiating the DCCP-UDP encapsulation versus native
DCCP . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 DCCP . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.5. Example of SDP use . . . . . . . . . . . . . . . . . . . . 14 5.5. Example of SDP use . . . . . . . . . . . . . . . . . . . . 15
6. Security Considerations . . . . . . . . . . . . . . . . . . . 15 6. Security Considerations . . . . . . . . . . . . . . . . . . . 16
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
7.1. UDP Port Allocation . . . . . . . . . . . . . . . . . . . 15 7.1. UDP Port Allocation . . . . . . . . . . . . . . . . . . . 17
7.2. DCCP Reset . . . . . . . . . . . . . . . . . . . . . . . . 15 7.2. DCCP Reset . . . . . . . . . . . . . . . . . . . . . . . . 17
7.3. SDP Attribute Allocation . . . . . . . . . . . . . . . . . 16 7.3. SDP Attribute Allocation . . . . . . . . . . . . . . . . . 17
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
9.1. Normative References . . . . . . . . . . . . . . . . . . . 16 9.1. Normative References . . . . . . . . . . . . . . . . . . . 18
9.2. Informative References . . . . . . . . . . . . . . . . . . 17 9.2. Informative References . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction 1. Introduction
The Datagram Congestion Control Protocol (DCCP), specified in The Datagram Congestion Control Protocol (DCCP) [RFC4340] is a
[RFC4340], is a transport-layer protocol that provides upper layers transport-layer protocol that provides upper layers with the ability
with the ability to use non-reliable congestion-controlled flows. to use non-reliable congestion-controlled flows. The current
The current specification for DCCP [RFC4340] specifies a direct specification for DCCP specifies a direct native encapsulation in
encapsulation in IPv4 or IPv6 packets. IPv4 or IPv6 packets.
[RFC5597] specifies how DCCP should be handled by devices that use DCCP support has been specified for devices that use Network Address
Network Address Translation (NAT) or Network Address and Port Translation (NAT) or Network Address and Port Translation (NAPT)
Translation (NAPT). However, there is a significant installed base [RFC5597]. However, there is a significant installed base of NAT/
of NAT/NAPT devices that do not support [RFC5597]. In the short NAPT devices that do not support RFC 5597. It is therefore useful to
term, it would be useful to have an encapsulation for DCCP that is have an encapsulation for DCCP that is compatible with this installed
compatible with this installed base of NAT/NAPT devices that support base of NAT/NAPT devices that support [RFC4787], but do not support
[RFC4787], but do not support [RFC5597]. This document specifies RFC 5597. This document specifies that encapsulation, which is
that encapsulation, which is referred to as DCCP-UDP. For referred to as DCCP-UDP. For convenience, the standard encapsulation
convenience, the standard encapsulation for DCCP [RFC4340] (including for DCCP [RFC4340] (including [RFC5596] as required) is referred to
[RFC5596] as required) is referred to as DCCP-STD. as DCCP-STD.
The encapsulation described in this document may also be used as a The encapsulation described in this document may also be used as a
transition mechanism to enable support for DCCP in devices that transition mechanism to enable support for DCCP in devices that
support UDP, but do not yet natively support DCCP. This therefore support UDP, but do not yet natively support DCCP. This also allows
also allows the DCCP transport to be implemented within an the DCCP transport to be implemented within an application using
application using DCCP-UDP. DCCP-UDP.
The document also updates the SDP specification for DCCP to convey The document also updates the SDP specification for DCCP to convey
the encapsulation type. In this respect only, it updates the method the encapsulation type. In this respect only, it updates the method
in [RFC5762]. in [RFC5762].
The DCCP-UDP encapsulation specified in this document supports all of The DCCP-UDP encapsulation specified in this document supports all of
the features contained in DCCP-STD, but with limited functionality the features contained in DCCP-STD, but with limited functionality
for partial checksums. for partial checksums.
Network optimisations for DCCP-STP and UDP may need to be updated to
allow these optimisations to take advantage of DCCP-UDP.
Encapsulation with an additional UDP protocol header can complicate
or prevent inspection of DCCP header fields by equipment along the
network path in the case where multiple DCCP connections share the
same UDP 4-tuple. For example, routers that wish to identify DCCP
ports to perform Equal-Cost Multi-Path routing, ECMP, network devices
that wish to inspect DCCP ports to inform algorithms for sharing the
network load across multiple links; firewalls that wish to inspect
DCCP ports and service codes to inform algorithms that implement
access rules; media gateways that inspect SDP information to derive
characteristics of the transport and session, etc.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. DCCP-UDP 3. DCCP-UDP
The basic approach is to insert a UDP [RFC0768] header between the IP The basic approach is to insert a UDP [RFC0768] header between the IP
header and the DCCP packet. Note that this is not a tunneling header and the DCCP packet. Note that this is not a tunneling
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would need to be updated by the NAT/NAPT. would need to be updated by the NAT/NAPT.
A device offering or using DCCP services via DCCP-UDP encapsulation 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 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 to a specified port utilising out-of-band signalling, such as the
Session Description Protocol (SDP). The DCCP-UDP server accepts Session Description Protocol (SDP). The DCCP-UDP server accepts
incoming packets over the UDP transport and passes the received incoming packets over the UDP transport and passes the received
packets to the DCCP protocol module, after removing the UDP packets to the DCCP protocol module, after removing the UDP
encapsulation. encapsulation.
A DCCP implementation MAY allow services to be simultaneously offered A DCCP implementation endpoint may simultaneously provide services
over any or all combinations of DCCP-STD and DCCP-UDP encapsulations over any or all combinations of DCCP-STD and/or DCCP-UDP
with IPv4 and IPv6. encapsulations with IPv4 and/or IPv6.
The basic format of a DCCP-UDP packet is: The basic format of a DCCP-UDP packet is:
+-----------------------------------+ +-----------------------------------+
| IP Header (IPv4 or IPv6) | Variable length | IP Header (IPv4 or IPv6) | Variable length
+-----------------------------------+ +-----------------------------------+
| UDP Header | 8 bytes | UDP Header | 8 bytes
+-----------------------------------+ +-----------------------------------+
| DCCP Generic Header | 12 or 16 bytes | DCCP Generic Header | 12 or 16 bytes
+-----------------------------------+ +-----------------------------------+
| Additional (type-specific) Fields | Variable length (could be 0) | Additional (type-specific) Fields | Variable length (could be 0)
+-----------------------------------+ +-----------------------------------+
| DCCP Options | Variable length (could be 0) | DCCP Options | Variable length (could be 0)
+-----------------------------------+ +-----------------------------------+
| Application Data Area | Variable length (could be 0) | Application Data Area | Variable length (could be 0)
+-----------------------------------+ +-----------------------------------+
Section 3.8 describes usage of UDP ports. This includes Section 3.8 describes usage of UDP ports. This includes
implementation of a DCCP-UDP encapsulation service as a daemon that implementation of a DCCP-UDP encapsulation service as a daemon that
listens on a well-known port, allowing multiplexing of different DCCP listens on a well-known port, allowing multiplexing of different DCCP
applications over the port. applications over the same port.
3.1. The UDP Header 3.1. The UDP Header
The format of the UDP header is specified in [RFC0768]: The format of the UDP header is specified in [RFC0768]:
0 1 2 3 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 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 | | Source Port | Dest Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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will generally be unaware whether DCCP is being encapsulated and will generally be unaware whether DCCP is being encapsulated and
hence do not update the inner checksum in the DCCP header. Standard hence do not update the inner checksum in the DCCP header. Standard
DCCP requires protection of the DCCP header fields, this justifies DCCP requires protection of the DCCP header fields, this justifies
any processing overhead incurred from calculating the UDP checksum. any processing overhead incurred from calculating the UDP checksum.
In addition, UDP NAT traversal does not support partial checksums. In addition, UDP NAT traversal does not support partial checksums.
Although this is still permitted end-to-end in the encapsulated DCCP Although this is still permitted end-to-end in the encapsulated DCCP
datagram, links along the path will treat these as UDP packets and datagram, links along the path will treat these as UDP packets and
can not enable special partial checksum processing. can not enable special partial checksum processing.
DCCP-UDP does not update or modify the operation of UDP. The UDP
transport protocol is used in the following way:
For DCCP-UDP, the function of the DCCP Checksum field is performed by For DCCP-UDP, the function of the DCCP Checksum field is performed by
the UDP checksum field. On transmit, the DCCP Checksum field SHOULD the UDP checksum field. On transmit, the DCCP Checksum field SHOULD
be set to zero. On receive, the DCCP Checksum field MUST be ignored. be set to zero. On receive, the DCCP Checksum field MUST be ignored.
The UDP checksum MUST NOT be zero for a UDP packet that is sent using 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 DCCP-UDP. If the received UDP Checksum field is zero, the packet
MUST be dropped. MUST be dropped [RFC5405].
If the UDP Length field is less than 20 (the UDP Header length and If the UDP Length field is less than 20 (the UDP Header length and
minimum DCCP-UDP header length), the packet MUST be dropped. minimum DCCP-UDP header length), the packet MUST be dropped
[RFC5405]..
If the UDP Checksum field, computed using standard UDP methods, is If the UDP Checksum field, computed using standard UDP methods, is
invalid, the packet MUST be dropped. invalid, the packet MUST be dropped [RFC5405].
If the UDP Length field in a received packet is less than the length 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 of the UDP header plus the entire DCCP-UDP header (including the
generic header and type-specific fields and options, if present), or 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 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 the beginning of the UDP header to the end of the packet, the packet
MUST be dropped. MUST be dropped.
3.3.1. Partial Checksums and the Minimum Checksum Coverage Feature 3.3.1. Partial Checksums and the Minimum Checksum Coverage Feature
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covers the entire DCCP datagram and the DCCP checksum is ignored on covers the entire DCCP datagram and the DCCP checksum is ignored on
receipt. An application that enables the partial checksums feature receipt. An application that enables the partial checksums feature
in the DCCP Module will therefore experience a service that is in the DCCP Module will therefore experience a service that is
functionally identical to using full DCCP checksum coverage. This is functionally identical to using full DCCP checksum coverage. This is
also the service that the application would have received if it had also the service that the application would have received if it had
used a network path that did not provide optimised processing for used a network path that did not provide optimised processing for
DCCP partial checksums. DCCP partial checksums.
3.4. Network Layer Options 3.4. Network Layer Options
A DCCP-UDP implementations MAY transfer network-layer options A DCCP-UDP implementation MAY transfer network-layer options intended
intended for DCCP to the network-layer header of the encapsulating for DCCP to the network-layer header of the encapsulating UDP packet.
UDP packet.
A DCCP-UDP endpoint that receives IP-options for the encapsulating A DCCP-UDP endpoint that receives IP-options for the encapsulating
UDP packet MAY forward these to the DCCP protocol module. If the UDP packet MAY forward these to the DCCP protocol module. If the
endpoint forwards a specific network layer option to the DCCP module, endpoint forwards a specific network layer option to the DCCP module,
it MUST also forward all subsequent packets with this option. it MUST also forward all subsequent packets with this option.
Consistent forwarding is essential for correct operation of many end- Consistent forwarding is essential for correct operation of many end-
to-end options. to-end options.
3.5. Explicit Congestion Notification 3.5. Explicit Congestion Notification
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part of the original packet that resulted in the message is included part of the original packet that resulted in the message is included
in the payload of the ICMP error message. The receiving endpoint can in the payload of the ICMP error message. The receiving endpoint can
therefore use this information to associate the ICMP error with the therefore use this information to associate the ICMP error with the
transport protocol instance that resulted in the ICMP message. When transport protocol instance that resulted in the ICMP message. When
DCCP-UDP is used, the error message and the payload of the ICMP error DCCP-UDP is used, the error message and the payload of the ICMP error
message relate to the UDP transport. message relate to the UDP transport.
DCCP-UDP endpoints SHOULD forward ICMP messages relating to a UDP DCCP-UDP endpoints SHOULD forward ICMP messages relating to a UDP
packet that carries a DCCP-UDP to the DCCP module. This may imply 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 translation of the payload of the ICMP message into a form that is
recognised by the DCCP stack. [ICMP] describes precautions that are recognised by the DCCP stack. [RFC5927] describes precautions that
desirable before TCP acts on the receipt of an ICMP message. Similar are desirable before TCP acts on the receipt of an ICMP message.
precautions are desirable prior to forwarding by DCCP-UDP to the DCCP Similar precautions are desirable prior to forwarding by DCCP-UDP to
module. the DCCP module.
The minimal length ICMP error message generated in response to The minimal length ICMP error message generated in response to
processing a UDP Datagram only identifies the Source UDP Port and processing a UDP Datagram only identifies the Source UDP Port and
Destination UDP Port. This ICMP message does not carry sufficient Destination UDP Port. This ICMP message does not carry sufficient
information to discover the encapsulated DCCP Port values. A DCCP- information to discover the encapsulated DCCP Port values. A DCCP-
UDP endpoint that supports multiple DCCP connections over the same UDP endpoint that supports multiple DCCP connections over the same
pair of UDP ports (see section Section 3.8) may not therefore be able pair of UDP ports (see section Section 3.8) may not therefore be able
to associate an ICMP message with a unique DCCP-UDP connection. to associate an ICMP message with a unique DCCP-UDP connection.
3.7. Path Maximum Transmission Unit Discovery 3.7. Path Maximum Transmission Unit Discovery
DCCP-UDP implementations SHOULD follow DCCP-STD section 14 with DCCP-UDP implementations MUST follow DCCP-STD [RFC4340], section 14
regard to determining the maximum packet size and the use of Path with regard to determining the maximum packet size and the use of
Maximum Transmission Unit Discovery (PMTUD). Path Maximum Transmission Unit Discovery (PMTUD). This requires the
processing of ICMP Destination Unreachable messages with a Code that
indicates that an unfragmentable packet was too large to be forwarded
(a "Datagram Too Big" message), as defined in RFC 4340.
An effect of encapsulation is to incur additional datagram overhead. An effect of encapsulation is to incur additional datagram overhead.
This will reduce the Maximum Packet Size (MPS) at the DCCP level. This will reduce the Maximum Packet Size (MPS) at the DCCP level.
3.8. Usage of the UDP port by DCCP-UDP 3.8. Usage of the UDP port by DCCP-UDP
A DCCP-UDP server (that is, an initially passive endpoint that wishes A DCCP-UDP server (that is, an initially passive endpoint that wishes
to receive DCCP-Request packets [RFC4340] over DCCP-UDP) listens for to receive DCCP-Request packets [RFC4340] over DCCP-UDP) listens for
connections on one or more UDP ports. UDP port number XXX IANA PORT connections on one or more UDP ports. UDP port number XXX IANA PORT
XXX has been reserved as the default listening UDP port for a DCCP- XXX has been reserved as the default listening UDP port for a DCCP-
UDP server. Some NAT/NAPT topologies may require using a non-default UDP server. Some NAT/NAPT topologies may require using a non-default
listening port. listening port.
The purpose of this IANA-assigned port is for the operating system or The purpose of this IANA-assigned port is for the operating system or
a framework to receive and process DCCP-UDP datagrams for delivery to a framework to receive and process DCCP-UDP datagrams for delivery to
the DCCP module (e.g. to support a DCCP-UDP daemon serving multiple the DCCP module (e.g. to support a system-wide DCCP-UDP daemon
DCCP applications or a DCCP-UDP server placed behind a firewall). serving multiple DCCP applications or a DCCP-UDP server placed behind
Because of this, the IANA-assigned port SHOULD NOT be used as the a firewall).
Destination UDP Port by a DCCP-UDP server listening for incoming
DCCP-UDP packets. An application-specific implementation SHOULD use An application-specific implementation SHOULD use an ephemeral port
an ephemeral port and advertise this port using outside means, e.g. and advertise this port using outside means, e.g. SDP. This method
SDP. of implementation SHOULD NOT use the IANA-assigned port to listen for
incoming DCCP-UDP packets.
A DCCP-UDP client provides UDP source and destination ports as well A DCCP-UDP client provides UDP source and destination ports as well
as DCCP source and destination ports at connection initiation time. as DCCP source and destination ports at connection initiation time.
A client SHOULD ensure that each DCCP connection maps to a single UDP A client SHOULD ensure that each DCCP connection maps to a single
connection by setting the UDP source port. Choosing a distinct DCCP-UDP connection by setting the UDP source port. Choosing a
source UDP port for each distinct DCCP connection ensures that UDP- distinct source UDP port for each distinct DCCP connection ensures
based flow identifiers differ whenever DCCP-based flow identifiers that UDP-based flow identifiers differ whenever DCCP-based flow
differ. Specifically, two connections with different <source IP identifiers differ. Specifically, two connections with different
address, source DCCP port, destination IP address, destination DCCP <source IP address, source DCCP port, destination IP address,
port> DCCP 4-tuples will have different <source IP address, source destination DCCP port> DCCP 4-tuples will have different <source IP
UDP port, destination IP address, destination UDP port> UDP 4-tuples. address, source UDP port, destination IP address, destination UDP
port> UDP 4-tuples.
A DCCP-UDP server SHOULD accept datagrams from any UDP source port. 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 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 by two endpoints each behind a NAPT. A DCCP-UDP server MUST
therefore demultiplex a DCCP-UDP flow using both the UDP source and therefore demultiplex a DCCP-UDP flow using both the UDP source and
destination port numbers and the encapsulated DCCP ports. This destination port numbers and the encapsulated DCCP ports. This
ensures than an active DCCP connection is uniquely identified by the ensures than an active DCCP connection is uniquely identified by the
6-tuple <source IP address, source UDP port, source DCCP port, 6-tuple <source IP address, source UDP port, source DCCP port,
destination IP address, destination UDP port, destination DCCP port>. destination IP address, destination UDP port, destination DCCP port>.
(The active state of a DCCP connection is defined in Section 3.8: A
DCCP connection becomes active following transmission of a DCCP-
Request, and become inactive after sending a DCCP-Close.)
This demultiplexing at a DCCP-UDP endpoint occurs in two stages: This demultiplexing at a DCCP-UDP endpoint occurs in two stages:
1) In the first stage, DCCP-UDP packets are demultiplexed using the 1) In the first stage, DCCP-UDP packets are demultiplexed using the
UDP 4-tuple: <source IP address, source UDP port, destination IP UDP 4-tuple: <source IP address, source UDP port, destination IP
address, destination UDP port>. address, destination UDP port>.
2) In the second stage, a receiving endpoint MUST ensure that two 2) In the second stage, a receiving endpoint MUST ensure that two
independent DCCP connections that were multiplexed to the same UDP independent DCCP connections that were multiplexed to the same UDP
4-tuple are not associated with the same connection in the DCCP 4-tuple are not associated with the same connection in the DCCP
module. The endpoint therefore needs to keep state for the set of module. The endpoint therefore needs to keep state for the set of
active DCCP-UDP endpoints using each combination of a UDP 4-tuple: active DCCP-UDP endpoints using each combination of a UDP 4-tuple:
<source IP address, source UDP port, destination IP address, <source IP address, source UDP port, destination IP address,
destination UDP port>. A DCCP endpoint MUST implement one of the two destination UDP port>. Two DCCP endpoint methods are specified. A
methods: DCCP-UDP implementation MUST implement exactly one of these:
o A DCCP server MAY accept only one active 6-tuple at any one time o The 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 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 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 and the DCCP Server SHOULD send a DCCP-Reset with with Reset Code
XXX IANA Port Reuse XXX, "Encapsulated Port Reuse". An endpoint XXX IANA Port Reuse XXX, "Encapsulated Port Reuse". An endpoint
that receives a DCCP-Reset with this reset code will clear its that receives a DCCP-Reset with this reset code will clear its
connection state, but MAY immediately try again using a different connection state, but MAY immediately try again using a different
4-tuple. This provides protection should the same UDP 4-tuple be 4-tuple. This provides protection should the same UDP 4-tuple be
re-used by multiple DCCP connections, ensuring that only one DCCP re-used by multiple DCCP connections, ensuring that only one DCCP
connection is established at one time. connection is established at one time.
o A DCCP server MAY support multiple DCCP connections over the same o The DCCP server may support multiple DCCP connections over the
UDP 4-tuple. In this method, the endpoint MUST then associate same UDP 4-tuple. In this method, the endpoint MUST then
each 6-tuple with a single DCCP connection. If an endpoint is associate each 6-tuple with a single DCCP connection. If an
unable to demultiplex the 6-tuple (e.g. due to internal resource endpoint is unable to demultiplex the 6-tuple (e.g. due to
limits), it MUST discard DCCP-UDP packets that do not match an internal resource limits), it MUST discard DCCP-UDP packets that
active 6-tuple instead of forwarding them to the DCCP module. The do not match an active 6-tuple instead of forwarding them to the
DCCP endpoint MAY send a DCCP-Reset with Reset Code XXX IANA Port DCCP module. The DCCP endpoint MAY send a DCCP-Reset with Reset
Reuse XXX, "Encapsulated Port Reuse", indicating the connection Code XXX IANA Port Reuse XXX, "Encapsulated Port Reuse",
has been closed, but may be retried using a different UDP 4-tuple. indicating the connection has been closed, but may be retried
using a different UDP 4-tuple.
3.9. Service Codes and the DCCP Port Registry 3.9. Service Codes and the DCCP Port Registry
This section clarifies the usage of DCCP Service Codes and the This section clarifies the usage of DCCP Service Codes and the
registration of server ports by DCCP-UDP. The section is not registration of server ports by DCCP-UDP. The section is not
intended to update the procedures for allocating Service Codes or intended to update the procedures for allocating Service Codes or
server ports. server ports.
There is one Service Code registry and one DCCP port registration There is one Service Code registry and one DCCP port registration
that apply to all combinations of encapsulation and IP version. A that apply to all combinations of encapsulation and IP version. A
DCCP Service Code specifies an application using DCCP regardless of DCCP Service Code specifies an application using DCCP regardless of
the combination of DCCP encapsulation and IP version. An application the combination of DCCP encapsulation and IP version. An application
may choose not to support some combinations of encapsulation and IP may choose not to support some combinations of encapsulation and IP
version, but its Service Code will remain registered for those version, but its Service Code will remain registered for those
combinations and the Service Code must not be used by other combinations and the Service Code must not be used by other
applications. An application should not register different Service applications. An application should not register different Service
Codes for different combinations of encapsulation and IP version. Codes for different combinations of encapsulation and IP version.
[RFC5595] provides additional information about DCCP Service Codes. [RFC5595] provides additional information about DCCP Service Codes.
Similarly, a port registration is applicable to all combinations of Similarly, a DCCP port registration is applicable to all combinations
encapsulation and IP version. Again, an application may choose not of encapsulation and IP version. Again, an application may choose
to support some combinations of encapsulation and IP version on its not to support some combinations of encapsulation and IP version on
registered port, although the port will remain registered for those its registered DCCP port, although the port will remain registered
combinations. Applications should not register different ports just for those combinations. Applications should not register different
for the purpose of using different combinations of encapsulation. DCCP ports just for the purpose of using different combinations of
encapsulation.
4. DCCP-UDP and Higher-Layer Protocols 4. DCCP-UDP and Higher-Layer Protocols
The encapsulation of a higher-layer protocol within DCCP MUST be the The encapsulation of a higher-layer protocol within DCCP MUST be the
same for both DCCP-STD and DCCP-UDP. Encapsulations of DTLS over same for both DCCP-STD and DCCP-UDP. Encapsulation of Datagram
DCCP is defined in [RFC5238] and RTP over DCCP is defined in Transport Layer Security (DTLS) over DCCP is defined in [RFC5238] and
[RFC5762]. This document therefore does not update these RTP over DCCP is defined in [RFC5762]. This document therefore does
encapsulations when using DCCP-UDP. not update these encapsulations when using DCCP-UDP.
5. Signaling the Use of DCCP-UDP 5. Signaling the Use of DCCP-UDP
Applications often signal transport connection parameters through Applications often signal transport connection parameters through
outside means, such as SDP. Applications that define such methods outside means, such as SDP. Applications that define such methods
for DCCP MUST define how the DCCP encapsulation is chosen, and MUST for DCCP MUST define how the DCCP encapsulation is chosen, and MUST
allow either encapsulation to be signaled. Where DCCP-STD and DCCP- allow either encapsulation to be signaled. Where DCCP-STD and DCCP-
UDP are both supported, DCCP-STD SHOULD be preferred. UDP are both supported, DCCP-STD SHOULD be preferred.
The Session Description Protocol (SDP) [RFC4566] and the offer/answer The Session Description Protocol (SDP) [RFC4566] and the offer/answer
model [RFC3264] can be used to negotiate DCCP sessions, and [RFC5762] model [RFC3264] can be used to negotiate DCCP sessions, and [RFC5762]
defines SDP extensions for signalling the use of an RTP session defines SDP extensions for signalling the use of an RTP session
running over DCCP connections. However, since [RFC5762] predates running over DCCP connections. However, since [RFC5762] predates
this document, it does not define a mechanism for signalling that the this document, it does not define a mechanism for signalling that the
DCCP-UDP encapsulation is to be used. This section updates [RFC5762] DCCP-UDP encapsulation is to be used. This section updates [RFC5762]
to describe how SDP can be used to signal RTP sessions running over to describe how SDP can be used to signal RTP sessions running over
the DCCP-UDP encapsulation. the DCCP-UDP encapsulation.
The new SDP suport specified in this section is expected to be useful The new SDP support specified in this section is expected to be
when the offering party is on the public Internet, or in the same useful when the offering party is on the public Internet, or in the
private addressing realm as the answering party. In this case, the same private addressing realm as the answering party. In this case,
DCCP-UDP server has a public address. The client may either have a the DCCP-UDP server has a public address. The client may either have
public address or be behind a NAT/NAPT. This is considered a a public address or be behind a NAT/NAPT. This scenario has the
scenario that has the potential to be an important use-case. Some potential to be an important use-case. Some other NAT/NAPT
other NAT/NAPT topologies may result in the advertised port being topologies may result in the advertised port being unreachable via
unreachable via the NAT/NAPT the NAT/NAPT.
5.1. Protocol Identification 5.1. Protocol Identification
SDP uses a media ("m=") line to convey details of the media format SDP uses a media ("m=") line to convey details of the media format
and transport protocol used. The ABNF syntax of a media line for and transport protocol used. The ABNF syntax [RFC5124] of a media
DCCP is as follows (from [RFC4566]: line for DCCP is as follows (from [RFC4566]):
media-field = %x6d "=" media SP port ["/" integer] SP proto media-field = %x6d "=" media SP port ["/" integer] SP proto
1*(SP fmt) CRLF 1*(SP fmt) CRLF
The proto field denotes the transport protocol used for the media, The proto field denotes the transport protocol used for the media,
while the port indicates the transport port to which the media is while the port indicates the transport port to which the media is
sent. Following [RFC5762]. This document defines the following five sent, following [RFC5762]. This document defines the following five
values of the proto field to indicate media transported using DCCP- values of the proto field to indicate media transported using DCCP-
UDP encapsulation: UDP encapsulation:
UDP/DCCP UDP/DCCP
UDP/DCCP/RTP/AVP UDP/DCCP/RTP/AVP
UDP/DCCP/RTP/SAVP UDP/DCCP/RTP/SAVP
UDP/DCCP/RTP/AVPF UDP/DCCP/RTP/AVPF
UDP/DCCP/RTP/SAVPF UDP/DCCP/RTP/SAVPF
The "UDP/DCCP" protocol identifier is similar to the "DCCP" protocol The "UDP/DCCP" protocol identifier is similar to the "DCCP" protocol
identifier defined in [RFC5762] and denotes the DCCP transport identifier defined in [RFC5762] and denotes the DCCP transport
protocol encapsulated in UDP, but not its upper-layer protocol. protocol encapsulated in UDP, but not its upper-layer protocol.
The "UDP/DCCP/RTP/AVP" protocol identifier refers to RTP using the The "UDP/DCCP/RTP/AVP" protocol identifier refers to RTP using the
RTP Profile for Audio and Video Conferences with Minimal Control RTP Profile for Audio and Video Conferences with Minimal Control
[RFC3511] running over the DCCP-UDP encapsulation. [RFC3551] running over the DCCP-UDP encapsulation.
The "UDP/DCCP/RTP/SAVP" protocol identifier refers to RTP using the The "UDP/DCCP/RTP/SAVP" protocol identifier refers to RTP using the
Secure Real-time Transport Protocol [RFC3711] running over the DCCP- Secure Real-time Transport Protocol [RFC3711] running over the DCCP-
UDP encapsulation. UDP encapsulation.
The "UDP/DCCP/RTP/AVPF" protocol identifier refers to RTP using the The "UDP/DCCP/RTP/AVPF" protocol identifier refers to RTP using the
Extended RTP Profile for RTCP-based Feedback [RFC4585]running over Extended RTP Profile for RTCP-based Feedback [RFC4585]running over
the DCCP-UDP encapsulation. the DCCP-UDP encapsulation.
The "UDP/DCCP/RTP/SAVPF" protocol identifier refers to RTP using the The "UDP/DCCP/RTP/SAVPF" protocol identifier refers to RTP using the
skipping to change at page 13, line 4 skipping to change at page 13, line 33
The use of ports with DCCP-UDP encapsulation is described further in The use of ports with DCCP-UDP encapsulation is described further in
Section 3.8. Section 3.8.
5.2. Signalling Encapsulated DCCP Ports 5.2. Signalling Encapsulated DCCP Ports
When using DCCP-UDP, the UDP port used for the encapsulation is When using DCCP-UDP, the UDP port used for the encapsulation is
signalled using the SDP "m=" line. The DCCP ports MUST NOT be signalled using the SDP "m=" line. The DCCP ports MUST NOT be
included in the "m=" line, but are instead signalled using a new SDP included in the "m=" line, but are instead signalled using a new SDP
attribute ("dccp-port") defined according to the following ABNF: attribute ("dccp-port") defined according to the following ABNF:
dccp-port-attr = %x61 "=dccp-port:" dccp-port dccp-port-attr = %x61 "=dccp-port:" dccp-port
dccp-port = 1*DIGIT dccp-port = 1*DIGIT
where DIGIT is as defined in [RFC4234]. This is a media level where DIGIT is as defined in [RFC5234]. This is a media level
attribute, that is not subject to the charset attribute. The attribute, that is not subject to the charset attribute. The
"a=dccp-port:" attribute MUST be included when the protocol "a=dccp-port:" attribute MUST be included when the protocol
identifiers described in Section 5.1 are used. identifiers described in Section 5.1 are used.
The use of ports with DCCP-UDP encapsulation is described further in The use of ports with DCCP-UDP encapsulation is described further in
Section 3.8. Section 3.8.
If the "a=rtcp:" attribute [RFC3605] is used, then the signalled port o If the "a=rtcp:" attribute [RFC3605] is used, then the signalled
is the DCCP port used for RTCP. If the "a=rtcp-mux" attribute port is the DCCP port used for RTCP.
[RFC5761] is negotiated, then RTP and RTCP are multiplexed onto a
single DCCP port, otherwise separate DCCP ports are used for RTP and o If the "a=rtcp-mux" attribute [RFC5761] is negotiated, then RTP
RTCP. In each case, only a single UDP port is used for the DCCP-UDP and RTCP are multiplexed onto a single DCCP port, otherwise
separate DCCP ports are used for RTP and RTCP [RFC5762].
In each case, only a single UDP port is used for the DCCP-UDP
encapsulation. encapsulation.
o If the "a=rtcp-mux" attribute is not present, then the second of
the two demultiplexing methods described in Section 3.8 MUST be
implemented, otherwise the second DCCP connection for the RTCP
flow will be rejected. For this reason, using "a=rtcp-mux" is
RECOMMENDED when using RTP over DCCP-UDP.
5.3. Connection Management 5.3. Connection Management
The "a=setup:" attribute is used in a manner compatible with The "a=setup:" attribute is used in a manner compatible with
[RFC5762] Section 5.3 to indicate which of the DCCP-UDP endpoints [RFC5762] Section 5.3 to indicate which of the DCCP-UDP endpoints
should initiate the DCCP-UDP connection establishment. should initiate the DCCP-UDP connection establishment.
5.4. Negotiating the DCCP-UDP encapsulation versus native DCCP 5.4. Negotiating the DCCP-UDP encapsulation versus native DCCP
An endpoint that supports both native DCCP and the DCCP-UDP An endpoint that supports both native DCCP and the DCCP-UDP
encapsulation may wish to signal support for both options in an SDP encapsulation may wish to signal support for both options in an SDP
offer, allowing the answering party the option of using native DCCP offer, allowing the answering party the option of using native DCCP
where possible, while falling back to the DCCP-UDP encapsulation where possible, while falling back to the DCCP-UDP encapsulation
otherwise. otherwise.
An approach to doing this might be to include candidates for the An approach to doing this might be to include candidates for the
DCCP-UDP encapsulation and native DCCP into an Interactive DCCP-UDP encapsulation and native DCCP into an Interactive
Connectivity Establishment (ICE) [RFC5245] exchange. Since DCCP is Connectivity Establishment (ICE) [RFC5245] exchange. Since DCCP is
connection-oriented, these candidates would need to be encoded into connection-oriented, these candidates would need to be encoded into
ICE in a manner analogous to TCP candidates defined in [ICE-TCP]. ICE in a manner analogous to TCP candidates defined in [RFC6544].
Both active and passive candidates could be supported for native Both active and passive candidates could be supported for native DCCP
DCCPx and DCCP-UDP encapsulation, as may DCCP simultaneous and DCCP-UDP encapsulation, as may DCCP simultaneous open [RFC5596].
open[RFC5596]. In choosing local preference values, it may make In choosing local preference values, it may make sense to to prefer
sense to to prefer DCCP-UDP over native DCCP in cases where low DCCP-UDP over native DCCP in cases where low connection setup time is
connection setup time is important, and to prioritise native DCCP in important, and to prioritise native DCCP in cases where low overhead
cases where low overhead is preferred (on the assumption that DCCP- is preferred (on the assumption that DCCP-UDP is more likely to work
UDP is more likely to work through legacy NAT, but has higher through legacy NAT, but has higher overhead). The details of this
overhead). encoding into ICE are left for future study.
The details of this encoding into ICE are left for future study. While ICE is appropriate for selecting basic use of DCCP-UDP versus
DCCP-STD, it may not be appropriate for negotiating different RTP
profiles with each transport encapsulation. The SDP Capability
Negotiation framework [RFC5939] may be be more suitable. Section 3.7
of RFC 5939 specifies how to provide attributes and transport
protocols as capabilities and negotiate them using the framework .The
details of the use of SDP Capability Negotiation with DCCP are left
for future study.
5.5. Example of SDP use 5.5. Example of SDP use
The example below shows an SDP offer, where an application signals The example below shows an SDP offer, where an application signals
support for DCCP-UDP: support for DCCP-UDP:
v=0 v=0
o=alice 1129377363 1 IN IP4 192.0.2.47 o=alice 1129377363 1 IN IP4 192.0.2.47
s=- s=-
c=IN IP4 192.0.2.47 c=IN IP4 192.0.2.47
t=0 0 t=0 0
skipping to change at page 15, line 8 skipping to change at page 16, line 8
The answering party will then attempt to establish a DCCP-UDP The answering party will then attempt to establish a DCCP-UDP
connection to the offering party. The connection request will use an connection to the offering party. The connection request will use an
ephemeral DCCP source port and DCCP destination port 5004. The UDP ephemeral DCCP source port and DCCP destination port 5004. The UDP
packet encapsulating that request will have UDP source port 40123 and packet encapsulating that request will have UDP source port 40123 and
UDP destination port 50234. UDP destination port 50234.
6. Security Considerations 6. Security Considerations
DCCP-UDP provides all of the security risk-mitigation measures DCCP-UDP provides all of the security risk-mitigation measures
present in DCCP-STD, and also all of the security risks. present in DCCP-STD, and also all of the security risks. It does not
maintain additional state at the encapsulation layer.
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.
The tunnel encapsulation recommends processing of ICMP messages The tunnel encapsulation recommends processing of ICMP messages
received for packets sent using DCCP-UDP and translation to allow use received for packets sent using DCCP-UDP and translation to allow use
by DCCP. [RFC5927] describes precautions that are desirable before by DCCP. [RFC5927] describes precautions that are desirable before
TCP acts on receipt of ICMP messages. Similar precautions are TCP acts on receipt of ICMP messages. Similar precautions are
desirable for endpoints processing ICMP for DCCP-UDP. desirable for endpoints processing ICMP for DCCP-UDP.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.
DCCP-UDP may also allow DCCP applications to pass through existing DCCP-UDP may also allow DCCP applications to pass through existing
firewall devices, if the administrators of the devices so choose. A firewall devices using rules for UDP, if the administrators of the
simple use may either allow all DCCP applications or allow none. devices so choose. A simple use may either allow all DCCP
applications or allow none.
A firewall than interprets this specification could inspect the A firewall that interprets this specification could inspect the
encapsualted DCCP header to filter based on DCCP information. Full encapsulated DCCP header to filter based on the inner DCCP header
control of DCCP connections by applications will require enhancements information. Full control of DCCP connections by applications will
to firewalls, as discussed in [RFC4340] and related RFCs (e.g. require enhancements to firewalls, as discussed in [RFC4340] and
[RFC5595]). related RFCs (e.g. [RFC5595]).
Datagram Transport Layer Security (DTLS) TLS provides mechanisms that
can be used to provide security protection for the encapsulated DCCP
packets. DTLS may be used in two ways:
o Individual DCCP connections may be protected in the same way that
DTLS is used with native DCCP [RFC5595]. This does not encrypt
the UDP transport header added by DCCP-UDP.
o This specification also permits the use of DTLS with the UDP
transport that encapsulates DCCP packets. When DTLS is used at
the encapsulation layer this protects the DCCP headers. This
prevents the headers from being inspected or updated by network
middleboxes (such as firewalls and NAPT). It also eliminates the
need for a spearate DTLS handshake for each DCCP connection.
7. IANA Considerations 7. IANA Considerations
This document requests IANA to make the allocations described in the This document requests IANA to make the allocations described in the
following sections. following sections.
7.1. UDP Port Allocation 7.1. UDP Port Allocation
IANA is requested to allocate a UDP port for the dccp-udp service. IANA is requested to allocate a UDP port for the DCCP-UDP service.
Use of this port is defined in section Section 3.8 This port is allocated for use by a transport service, rather than an
application. In this case, the name of the transport should
explicitly appear in the registry. Use of this port is defined in
section Section 3.8
XXX Note: IANA is requested to replace all occurrences of "XXX IANA XXX Note: IANA is requested to replace all occurrences of "XXX IANA
PORT XXX" by the allocated port value prior to publication. XXX PORT XXX" by the allocated port value prior to publication. XXX
7.2. DCCP Reset 7.2. DCCP Reset
IANA is requested to assign a new DCCP Reset Code in the DCCP Reset IANA is requested to assign a new DCCP Reset Code in the DCCP Reset
Codes Registry, with the short description "Encapsulated Port Reuse". Codes Registry, with the short description "Encapsulated Port Reuse".
This code applies to all DCCP congestion control IDs and should be 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 allocated a value less than 120 decimal. Use of this reset code is
skipping to change at page 17, line 12 skipping to change at page 18, line 28
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
August 1980. August 1980.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3605] Huitema, C., "Real Time Control Protocol (RTCP) attribute [RFC3605] Huitema, C., "Real Time Control Protocol (RTCP) attribute
in Session Description Protocol (SDP)", RFC 3605, in Session Description Protocol (SDP)", RFC 3605,
October 2003. October 2003.
[RFC4234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 4234, October 2005.
[RFC4340] Kohler, E., Handley, M., and S. Floyd, "Datagram [RFC4340] Kohler, E., Handley, M., and S. Floyd, "Datagram
Congestion Control Protocol (DCCP)", RFC 4340, March 2006. Congestion Control Protocol (DCCP)", RFC 4340, March 2006.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008. Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5762] Perkins, C., "RTP and the Datagram Congestion Control [RFC5762] Perkins, C., "RTP and the Datagram Congestion Control
Protocol (DCCP)", RFC 5762, April 2010. Protocol (DCCP)", RFC 5762, April 2010.
9.2. Informative References 9.2. Informative References
[ICE-TCP] Rosenberg, "TCP Candidates with Interactive Connectivity
Establishment (ICE), IETF Work-in-Progress.".
[ICMP] Gont, "ICMP attacks against TCP, IETF Work-in-Progress.".
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264, with Session Description Protocol (SDP)", RFC 3264,
June 2002. June 2002.
[RFC3511] Hickman, B., Newman, D., Tadjudin, S., and T. Martin, [RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
"Benchmarking Methodology for Firewall Performance", Video Conferences with Minimal Control", STD 65, RFC 3551,
RFC 3511, April 2003. July 2003.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)", Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, March 2004. RFC 3711, March 2004.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006. Description Protocol", RFC 4566, July 2006.
[RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
"Extended RTP Profile for Real-time Transport Control "Extended RTP Profile for Real-time Transport Control
Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585,
July 2006. July 2006.
[RFC4762] Lasserre, M. and V. Kompella, "Virtual Private LAN Service
(VPLS) Using Label Distribution Protocol (LDP) Signaling",
RFC 4762, January 2007.
[RFC4787] Audet, F. and C. Jennings, "Network Address Translation [RFC4787] Audet, F. and C. Jennings, "Network Address Translation
(NAT) Behavioral Requirements for Unicast UDP", BCP 127, (NAT) Behavioral Requirements for Unicast UDP", BCP 127,
RFC 4787, January 2007. RFC 4787, January 2007.
[RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for [RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for
Real-time Transport Control Protocol (RTCP)-Based Feedback Real-time Transport Control Protocol (RTCP)-Based Feedback
(RTP/SAVPF)", RFC 5124, February 2008. (RTP/SAVPF)", RFC 5124, February 2008.
[RFC5238] Phelan, T., "Datagram Transport Layer Security (DTLS) over [RFC5238] Phelan, T., "Datagram Transport Layer Security (DTLS) over
the Datagram Congestion Control Protocol (DCCP)", the Datagram Congestion Control Protocol (DCCP)",
RFC 5238, May 2008. RFC 5238, May 2008.
[RFC5245] Rosenberg, J., "Interactive Connectivity Establishment [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment
(ICE): A Protocol for Network Address Translator (NAT) (ICE): A Protocol for Network Address Translator (NAT)
Traversal for Offer/Answer Protocols", RFC 5245, Traversal for Offer/Answer Protocols", RFC 5245,
April 2010. April 2010.
[RFC5405] Eggert, L. and G. Fairhurst, "Unicast UDP Usage Guidelines
for Application Designers", BCP 145, RFC 5405,
November 2008.
[RFC5595] Fairhurst, G., "The Datagram Congestion Control Protocol [RFC5595] Fairhurst, G., "The Datagram Congestion Control Protocol
(DCCP) Service Codes", RFC 5595, September 2009. (DCCP) Service Codes", RFC 5595, September 2009.
[RFC5596] Fairhurst, G., "Datagram Congestion Control Protocol [RFC5596] Fairhurst, G., "Datagram Congestion Control Protocol
(DCCP) Simultaneous-Open Technique to Facilitate NAT/ (DCCP) Simultaneous-Open Technique to Facilitate NAT/
Middlebox Traversal", RFC 5596, September 2009. Middlebox Traversal", RFC 5596, September 2009.
[RFC5597] Denis-Courmont, R., "Network Address Translation (NAT) [RFC5597] Denis-Courmont, R., "Network Address Translation (NAT)
Behavioral Requirements for the Datagram Congestion Behavioral Requirements for the Datagram Congestion
Control Protocol", BCP 150, RFC 5597, September 2009. Control Protocol", BCP 150, RFC 5597, September 2009.
[RFC5761] Perkins, C. and M. Westerlund, "Multiplexing RTP Data and [RFC5761] Perkins, C. and M. Westerlund, "Multiplexing RTP Data and
Control Packets on a Single Port", RFC 5761, April 2010. Control Packets on a Single Port", RFC 5761, April 2010.
[RFC5927] Gont, F., "ICMP Attacks against TCP", RFC 5927, July 2010. [RFC5927] Gont, F., "ICMP Attacks against TCP", RFC 5927, July 2010.
[RFC5939] Andreasen, F., "Session Description Protocol (SDP)
Capability Negotiation", RFC 5939, September 2010.
[RFC6544] Rosenberg, J., Keranen, A., Lowekamp, B., and A. Roach,
"TCP Candidates with Interactive Connectivity
Establishment (ICE)", RFC 6544, March 2012.
Authors' Addresses Authors' Addresses
Tom Phelan Tom Phelan
Sonus Networks Sonus Networks
7 Technology Dr. 7 Technology Dr.
Westford, MA 01886 Westford, MA 01886
US US
Phone: +1 978 614 8456 Phone: +1 978 614 8456
Email: tphelan@sonusnet.com Email: tphelan@sonusnet.com
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