+++ /dev/null
-.pl 10.0i
-.po 0
-.ll 7.2i
-.lt 7.2i
-.nr LL 7.2i
-.nr LT 7.2i
-.ds LF Riikonen
-.ds RF FORMFEED[Page %]
-.ds CF
-.ds LH Internet-Draft
-.ds RH 15 January 2007
-.ds CH
-.na
-.hy 0
-.in 0
-.nf
-Network Working Group P. Riikonen
-Internet-Draft
-draft-riikonen-silc-multimedia-session-00.txt 15 January 2007
-Expires: 15 July 2007
-
-.in 3
-
-.ce 2
-Multimedia Sessions in SILC protocol
-<draft-riikonen-silc-multimedia-session-00.txt>
-
-.ti 0
-Status of this Draft
-
-By submitting this Internet-Draft, each author represents that any
-applicable patent or other IPR claims of which he or she is aware
-have been or will be disclosed, and any of which he or she becomes
-aware will be disclosed, in accordance with Section 6 of BCP 79.
-
-Internet-Drafts are working documents of the Internet Engineering
-Task Force (IETF), its areas, and its working groups. Note that
-other groups may also distribute working documents as Internet-
-Drafts. Internet-Drafts are draft documents valid for a maximum of
-six months and may be updated, replaced, or obsoleted by other
-documents at any time. It is inappropriate to use Internet-Drafts as
-reference material or to cite them other than as "work in progress".
-
-The list of current Internet-Drafts can be accessed at
-http://www.ietf.org/1id-abstracts.html
-The list of Internet-Draft Shadow Directories can be accessed at
-http://www.ietf.org/shadow.html.
-
-
-.ti 0
-Abstract
-
-This document defines the use of multimedia protocols and the set up
-of multimedia sessions in the Secure Internet Live Conferencing (SILC)
-protocol [SILC1].
-
-
-.ti 0
-Table of Contents
-
-.nf
-1 Introduction .................................................. 2
- 1.1 Requirements Terminology .................................. 2
-2 Recommended Protocol .......................................... 2
-3 Session Description Protocol (SDP) ............................ 2
- 3.1 SDP field usage in SILC ................................... 3
- 3.2 SDP Examples .............................................. 5
-4 Session Initiation Protocol (SIP) ............................. 6
-5 Other Protocols ............................................... 6
-6 Security Considerations ....................................... 7
-7 References .................................................... 7
-8 Author's Address .............................................. 7
-9 Full Copyright Statement ...................................... 7
-
-
-.ti 0
-1 Introduction
-
-This document defines the use of multimedia protocols and the set up
-of multimedia sessions in the Secure Internet Live Conferencing (SILC)
-protocol [SILC1]. The SILC protocol supports multimedia messages
-with the Message Payload [SILC2] and SILC_MESSAGE_FLAG_DATA which
-has the ability to define what type of content is delievered within
-the payload. The Message Payload is used to encapsulate the multimedia
-session set up procedure and the actual multimedia session data. We
-define the recommended multimedia session protocol for SILC and also
-consider some other protocols in the scope of SILC.
-
-
-.ti 0
-1.1 Requirements Terminology
-
-The keywords MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT, RECOMMENDED,
-MAY, and OPTIONAL, when they appear in this document, are to be
-interpreted as described in [RFC2119].
-
-
-.ti 0
-2 Recommended Protocol
-
-Since SILC protocol can encapsulate practically any protocol for setting
-up a multimedia session we have selected the Session Description Protocol
-(SDP) as RECOMMENDED protocol. It was chosen for its maturity, simplicity
-and versatility. If multimedia features are implemented in SILC
-application it is recommended that at least support for SDP is added.
-
-
-.ti 0
-3 Session Description Protocol (SDP)
-
-The SDP [SDP] protocol defines a general purpose multimedia session
-description protocol. SDP is one of the simplest protocols to negotiate
-multimedia sessions and is suited perfectly for SILC protocol. Since SDP
-does not itself define how it is used to set up the session, we define it
-here for SILC. The definition is based on the [RFC3264] and [RFC4145].
-
-In SILC the SDP messages are sent as data messages (MIME message). They
-can be destined directly to a client for direct conferencing, or to a
-channel for group conferencing. It is also possible to send the message
-directly to client to invite them to group conferencing before they have
-joined the channel. The MIME type used is application/sdp.
-
-To set up a multimedia session a client sends SILC message with
-SILC_MESSAGE_FLAG_DATA and SILC_MESSAGE_FLAG_REQUEST flags set and with
-MIME SDP message in the message payload. If the receiver wants to
-participate in the multimedia session it sends MIME SDP message back with
-SILC_MESSAGE_FLAG_DATA and SILC_MESSAGE_FLAG_REPLY flags set to the
-sender. If reply is not received after an application defined period of
-time the message may be retransmitted or the session set up may be
-terminated.
-
-After reply has been received the multimedia session is started according
-to the SDP and all multimedia data is sent using SILC data messages. When
-performing peer-to-peer connection the SDP defines which party initiates
-the connection. After initiation the SILC Key Exchange protocol MUST be
-performed. The resulted key material will be used to protect the multimedia
-session. Multimedia data transmission may start after the key exchange
-has been performed. When performing group conferencing all parties
-independently connect to the SILC server specified in the SDP. In other
-cases when performing the multimedia session inside the SILC network, any
-party may start transmitting the multimedia data after the SDPs have been
-exchanged.
-
-To terminate the session, or to reject incoming request, an MD5 digest
-MUST be computed from the original SDP data, and the digest is sent back
-with the SILC_MESSAGE_FLAG_DATA and SILC_MESSAGE_FLAG_STOP flags set.
-The receiver of such message should verify the MD5 digest and terminate
-the session if it matches any active session. The session may also be
-terminated by closing network connection. In group sessions simply by
-leaving the channel terminates the session. The original sender of the
-SDP message may send the terminating message to notify all clients on the
-channel to terminate the session. If the original sender on channel
-receives the terminating message it takes no action on it.
-
-.ti 0
-3.1 SDP field usage in SILC
-
-The Encryption Keys (k=) field describes encryption key to protect the
-multimedia session. As SILC protocol transport and the multimedia session
-is secured by default this field SHOULD NOT be used.
-
-
-The Origin (o=) field describes from where the session originates. The
-<username> sub-field is the sender's SILC nickname. Examples:
-
- o=foobar 2890844521 2890842804 IN IP4 10.2.1.7
-
-
-The Connection Data (c=) field describes the connection information for
-the multimedia session. When performing peer-to-peer multimedia session
-the <network type> is 'IN', indicating Internet connection. When
-performing multimedia session inside SILC network it is 'SILC'. When
-the 'SILC' network type is used the <address type> and <connection address>
-sub-fields are omitted. Examples:
-
- c=SILC
- c=IN IP4 10.2.1.7
-
-
-The Media Announcements (m=) field describes the media information for the
-multimedia session. If the network type in c= field is 'SILC' the <port>
-sub-field MUST be set to 9 (discard). The <transport> for RTP over UDP
-is 'RTP/AVP', for RTP over TCP it is 'TCP/RTP/AVP', and for non-RTP protocol
-over UDP it is 'udp' and over TCP it is 'tcp'. The <fmt> sub-field
-includes the RTP media payload number when using RTP. When using non-RTP
-protocol it includes MIME subtype. Examples:
-
- c=SILC
- m=audio 9 TCP/RTP/AVP 3
- a=rtpmap:3 GSM/8000
-
- c=SILC
- m=audio 9 tcp mpeg
-
-
-The Attributes (a=) field can be used to set various session and media
-specific attributes. For SILC we define attribute "silc".
-
- a=silc:<session type> <parameters>
-
-The <session type> is either "direct" or "group". When it is "direct"
-and the c= field defines a connection point the connection will be
-peer-to-peer connection to the remote client. If it is "group" and the
-the c= field defines a connection point the connection will be to a remote
-SILC server for group conferencing. If c= field includes "SILC" network
-type, then "direct" is for direct session with a client in SILC network
-and "group" is for group conferencing in SILC network. If the "silc"
-attribute is omitted the session type is expected to be "direct". The
-following parameters are defined for attribute "silc".
-
- channel The name of the channel for group conferencing.
- Can be used only with "group" session type.
- More than one channel parameters may be defined.
-
-
-The [RFC4145] specifies a "setup" attribute that defines which party of the
-session will initiate the connection when performing peer-to-peer session.
-Its use in SILC is as specified in [RFC4145] and MUST be present in SDP
-when the c= field includes an actual connection point and when the "silc"
-attribute session type is "direct", or if the attribute is not present at
-all. When performing group conferencing each party always need to create
-the connection to the server and the "setup" attribute need not be present
-in SDP.
-
-.ti 0
-3.2 SDP Examples
-
- v=0
- o=foobar 2890844521 2890842804 IN IP4 10.2.1.100
- s=peer-to-peer example
- t=0 0
- m=audio 5000 TCP/RTP/AVP 3
- c=IN IP4 10.2.1.100
- a=rtpmap:3 GSM/8000
- a=silc:direct
- a=setup:active
-
-This example sets up a peer-to-peer session to remote client at
-10.2.1.100 at port 5000.
-
- v=0
- o=foobar 2890844521 2890842804 IN IP4 10.2.1.32
- s=Group conferencing example
- c=IN IP4 10.2.1.7
- t=0 0
- a=silc:group channel=foobar
- m=audio 706 TCP/RTP/AVP 3
- a=rtpmap:3 GSM/8000
-
-This example sets up a session to a remote SILC server 10.2.1.7 at port
-706. Once connected the channel "foobar" will be joined for group
-conferencing.
-
- v=0
- o=foobar 2890844521 2890842804 IN IP4 10.2.1.32
- s=SILC network chat example
- c=SILC
- t=0 0
- m=audio 9 TCP/RTP/AVP 3
- a=rtpmap:3 GSM/8000
-
-This example sets up a session inside SILC network with the remote user
-"foobar".
-
- v=0
- o=foobar 2890844521 2890842804 IN IP4 10.2.1.32
- s=SILC network group conferencing example
- t=0 0
- m=audio 9 TCP/RTP/AVP 3
- c=SILC
- a=rtpmap:3 GSM/8000
- a=silc:group channel=group-chat
-
-This example sets up a group conferencing session inside SILC network on
-channel "group-chat".
-
-
-.ti 0
-4 Session Initiation Protocol (SIP)
-
-The SIP [SIP] protocol is a general purpose protocol for setting up,
-modifying and terminating different kinds of sessions, including
-multimedia sessions. The SIP protocol use the SDP to describe the
-multimedia session.
-
-In SILC the SIP messages are sent as data messages (MIME message). They
-can be destined directly to a client for direct conferencing, or to a
-channel for group conferencing. It is also possible to send the message
-directly to client to invite them to group conferencing before they have
-joined the channel. The MIME type used is application/sip. The
-SILC_MESSAGE_FLAG_DATA flag must be set in each message and the message
-payload includes a MIME SIP message. The actual SIP session set up and
-termination is described in the SIP protocol specification, and SILC
-protocol merely provides a secure transport for the session. After the
-session is set up all multimedia data is sent using SILC data messages.
-The MIME type for the multimedia data messages is defined during the SIP
-session set up.
-
-The rules for SDP fields described in previous section also applies for
-SDP with SIP in the context of SILC.
-
-Proxy and redirection servers usually would not be used in the context of
-SILC, unless the sessions are redirected to outside SILC network. This
-may compromise the security of the session.
-
-The S/MIME need not be used when using SIP in SILC protocol. The SILC
-protocol transport and the created multimedia session is secured by
-default.
-
-
-.ti 0
-5 Other Protocols
-
-There are other open and proprietary protocols for setting up multimedia
-sessions. One important is H.323 using the H.225 to set up the session.
-This document should later define the use of H.323 with SILC.
-Practically any protocol to set up multimedia sessions may be used with
-SILC by using SILC as a secure transport to set up the session, and to use
-SILC data messages (MIME messages) to secure and deliver the actual
-multimedia data once the session has been established.
-
-
-.ti 0
-6 Security Considerations
-
-Security is central to the design of this protocol, and these security
-considerations permeate the specification. Common security considerations
-such as keeping private keys truly private and using adequate lengths for
-symmetric and asymmetric keys must be followed in order to maintain the
-security of this protocol.
-
-
-.ti 0
-7 References
-
-[SILC1] Riikonen, P., "Secure Internet Live Conferencing (SILC),
- Protocol Specification", Internet Draft, June 2003.
-
-[SILC2] Riikonen, P., "SILC Packet Protocol", Internet Draft,
- June 2003.
-
-[RFC3264] Rosenberg, J., et. al., "An Offer/Answer Model with the
- Session Description Protocol (SDP)", RFC 3264, June 2002.
-
-[RFC4145] Yon, D., et. al., "TCP-Based Media Transport in the
- Session Description Protocol (SDP)", RFC 4145, September
- 2005.
-
-[SIP] Rosenberg, J., et. al., "SIP: Session Initiation Protocol",
- RFC 3261, June 2002.
-
-
-
-.ti 0
-8 Author's Address
-
-.nf
-Pekka Riikonen
-Helsinki
-Finland
-
-EMail: priikone@iki.fi
-
-
-.ti 0
-9 Full Copyright Statement
-
-Copyright (C) The Internet Society (2007).
-
-This document is subject to the rights, licenses and restrictions
-contained in BCP 78, and except as set forth therein, the authors
-retain all their rights.
-
-This document and the information contained herein are provided on an
-"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
-OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
-ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
-INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
-INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
-WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
projects / runtime.git / blobdiff