Network Working Group J. Manner
Internet-Draft University of Helsinki
Intended status: Standards Track June 14, 2007
Expires: December 16, 2007
Generic Internet Signaling Transport over DCCP and DTLS
draft-manner-nsis-gist-dccp-00.txt
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Copyright (C) The IETF Trust (2007).
Abstract
The General Internet Signaling Transport (GIST) protocol
specification supports two transport modes: UDP for very infrequent
messaging, and TCP for all other cases. However, with TCP comes
certain undesirable features, e.g., head of line blocking, which
affect performance when a number of sessions are multiplexed over the
same TCP connection. In certain environments and deployment
scenarios, an unreliable, but still congestion controlled, transport
would be needed. This specification proposes DCCP as a transport
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protocol for GIST.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology and Abbreviations . . . . . . . . . . . . . . . . . 4
3. DCCP Transport for GIST . . . . . . . . . . . . . . . . . . . . 4
3.1. MA Protocol Types . . . . . . . . . . . . . . . . . . . . . 4
3.2. Bit-Level Formats . . . . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6
Intellectual Property and Copyright Statements . . . . . . . . . . 7
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1. Introduction
The NSIS protocol suite currently includes the General Internet
Signaling Transport (GIST) [I-D.ietf-nsis-ntlp], and two NSIS
Signaling Layer Protocols (NSLP) for NAT/Firewall configuration
[I-D.ietf-nsis-nslp-natfw] and QoS signaling
[I-D.ietf-nsis-qos-nslp]. GIST provides a uniform transport service
to the NSLP layer, where these higher layer protocols can indicate
the type of service they require from GIST, e.g., secure or unsecure,
reliable or unreliable. When GIST sets up Messaging Associations
(MA) between nodes in the network, it can multiplex several sessions
over one MA, provided that the transport characteristics requested by
the NSLP protocols are met.
Currently, GIST supports two transport protocols. D-mode is run over
UDP and because it lacks congestion control, it can only be used for
infrequent messaging between nodes. C-mode is run over TCP and
provides a reliable congestion controlled service. However, with TCP
comes certain undesirable features, e.g., head of line blocking,
which affect performance when a number of sessions are multiplexed
over the same TCP connection. If the first segment of a window of
data is lost or delayed, TCP makes sure all data is still correctly
received in order at the receiver. This causes subsequent data to be
delayed until the loss of a segment is recovered. Thus, when GIST
messages are multiplexed over the same MA, if a segment carrying a
GIST message is lost in the beginning of the transmit window, all
subsequent messages are delayed, too. In certain environments and
deployment scenarios, an unreliable, but still congestion controlled,
transport would be needed.
This specification proposes the Datagram Congestion Control Protocol
(DCCP) [RFC4340] as a transport protocol for GIST. DCCP enables
congestion controlled and unreliable datagram service to the NSLP
layer. A further benefit of DCCP is that a new congestion control
mechanism targeted to signaling transport can be designed and
deployed for GIST in the future. Also the work on DCCP Service Codes
[I-D.fairhurst-dccp-serv-codes] can be used with this specification.
This specification does not require any changes to the GIST or DCCP
protocols. We propose two new protocols to be used with GIST
Messaging Associations:
1. Forwards-DCCP: for using DCCP in unsecure mode
2. Datagram Transport Layer Security
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2. Terminology and Abbreviations
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 BCP 14, RFC 2119
[RFC2119].
All other terminology is taken from the GIST specification
[I-D.ietf-nsis-ntlp].
3. DCCP Transport for GIST
Currently, the GIST specification supports Forwards-TCP and TLS. The
DCCP protocol is used with GIST in a similar way as TCP. The
querying node opens a forward connection towards the responder.
Support for this protocol is OPTIONAL.
If this protocol is offered, the MA-protocol-options data MUST also
be carried in the Stack-Configuration-Data object. The MA-protocol-
options field formats are:
1. Query: no information apart from the field header.
2. Response: a 2 byte port number at which the connection will be
accepted, followed by 2 padding bytes.
3.1. MA Protocol Types
We propose two new protocols to be used with GIST Messaging
Associations:
1. Forwards-DCCP: for using DCCP in unsecure mode
2. Datagram Transport Layer Security
The first protocol is meant to provide unsecure, unreliable, and
congestion controlled transport service to NSLP applications. The
second protocol adds security, thus, providing secure, unreliable and
congestion controlled service. An NSLP layer protocol can indicate
these preferences in the GIST API SendMessage primitive and the
Transfer-Attributes parameters.
Initially DTLS is used in conjunction with DCCP. Support for this
protocol in conjunction with DCCP is RECOMMENDED; associations using
it can carry messages with transfer attributes requesting
confidentiality and integrity protection. The description of TLS
usage in the GIST specification, Section 5.7.3. [I-D.ietf-nsis-ntlp]
apply also to DTLS.
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3.2. Bit-Level Formats
The MA-protocol-options field in the Stack-Configuration-Data MUST be
used with DCCP. The responder indicates the port number where it
will accept the DCCP connection.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DCCP port number | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4. Security Considerations
This specification does not add new security considerations to what
has already been raised in the GIST and DCCP protocols themselves.
DCCP can use DTLS as specified in [I-D.ietf-dccp-dtls].
5. IANA Considerations
This specification requests IANA to allocate two new MA-Protocol-ID
values
o Forwards-DCCP with a recommended value of 4.
o Datagram Transport Layer Security with a recommended value of 5.
6. References
6.1. Normative References
[I-D.ietf-dccp-dtls]
Phelan, T., "Datagram Transport Layer Security (DTLS) over
the Datagram Congestion Control Protocol (DCCP)",
draft-ietf-dccp-dtls-00 (work in progress), May 2007.
[I-D.ietf-nsis-ntlp]
Schulzrinne, H. and R. Hancock, "GIST: General Internet
Signalling Transport", draft-ietf-nsis-ntlp-13 (work in
progress), April 2007.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4340] Kohler, E., Handley, M., and S. Floyd, "Datagram
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Congestion Control Protocol (DCCP)", RFC 4340, March 2006.
6.2. Informative References
[I-D.fairhurst-dccp-serv-codes]
Fairhurst, G., "The DCCP Service Code",
draft-fairhurst-dccp-serv-codes-03 (work in progress),
March 2007.
[I-D.ietf-nsis-nslp-natfw]
Stiemerling, M., "NAT/Firewall NSIS Signaling Layer
Protocol (NSLP)", draft-ietf-nsis-nslp-natfw-14 (work in
progress), March 2007.
[I-D.ietf-nsis-qos-nslp]
Manner, J., "NSLP for Quality-of-Service Signaling",
draft-ietf-nsis-qos-nslp-14 (work in progress), June 2007.
Author's Address
Jukka Manner
University of Helsinki
P.O. Box 68
University of Helsinki FIN-00014 University of Helsinki
Finland
Phone: +358 9 191 51298
Email: jmanner@cs.helsinki.fi
URI: http://www.cs.helsinki.fi/u/jmanner/
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