Session Description Protocol (SDP)

RFC 4566

The session description protocol is what describes the session being requested. The SDP is carried in the message body of a SIP request/response. Each attribute line consists of an attribute identified by a single letter, followed by a value. The attributes defined for SDP are:

• v=protocol version: This is the version of SDP being used to create the SDP.
• o=owner/creator and session identifier: The identity of the session initiator.
• s=session name: Optional name that can be given to the session.
• i=session information: Additional information that the creator of the session wishes to share with participants.
• u=URI of description: This contains the URI of a Web site that may contain additional information about the session.
• e=email address: This usually contains the e-mail address of the creator, where participants can acquire more information.
• p=phone number: The contact phone number where more information can be provided about the session.
• c=connection information: Additional information about the connection for the session.
• b=bandwidth information: The amount of bandwidth to be provided for the session.
• z=time zone adjustments: Any time zone adjustments to be considered.
• k=encryption keys: The encryption keys for the session.
• a=zero or more session attribute lines: The number of attribute lines in the SDP.

Time Description

SDP Media Description

SDP Media Attribute Lines (a=)

• cat = category
• keywds = keywords
• tool = name and version of tool
• ptime = packet time
• maxptime = maximum packet time
• recvonly = receive-only mode
• sendrecv = send and receive mode
• orient = whiteboard orientation
• type = conference type
• charset = character set
• sdplang = language tag
• lang = language tag
• framerate = frame rate
• quality = quality
• fmtp = format-specific parameters
• rtpmap = rtpmap attribute
• curr = current status attribute
• des = desired-status attribute
• conf = confirm-status attribute
• mid = media stream identification attribute
• group = group attribute
• a = rtcp