FEC framework Configuration Signaling

1
FEC framework Configuration Signaling

• draft-ietf-fecframe-config-signaling-00.txt
• IETF 72

Rajiv Asati
2
Agenda

• Motivation
• Solution
• Solution Overview
• Encoding Format
• Multicasting Method
• Unicasting Method
• Changes since the last version
• Next step

3
Motivation

• Per FEC Framework, the FEC encoder and FEC
  decoder must have the common FEC Framework
  Configuration Information (FFCI) to perform the
  FEC operation.
• The following configuration parameters must be
  communicated between the FEC encoder and FEC
  decoder(s) -
• Identification of Source Flow(s)
• Identification of the repair flow(s)
• Identification of FEC Scheme
• Length of Source FEC payload ID
• FEC Scheme Specific Information (FSSI)
• How can these parameters be signaled between FEC
  devices ?

4
Solution

• The draft describes a solution for dynamically
  signaling the FEC Framework Configuration
  Information (FFCI) between FEC sender (or
  encoder) and receiver(s) (or decoders).
• Solution defines two signaling methods -
• Session Announcement Protocol for Multicasting
• Individual application protocol for Unicasting
  No dedicated protocol.

FEC_Sender2--------- --------FEC_Receiver2
FEC_Sender1-----IP/
MPLS network
-----------FEC_Receiver11
-----------FEC_Receiver12
-----------FEC_Receiver1
3
5
Solution

• The solution can be utilized by any FEC scheme
  and/or any Content Delivery Protocol (CDP).
  Hence, it is independent of the
• FEC scheme,
• Content Delivery Protocol
• Encoding format of the configuration information
  (for multicast).

6
Solution DetailEncoding Format

• Each instance of the FEC Framework must use a
  single encoding format to describe all of the
  configuration information (FFCI) associated with
  that instance.
• Whatever encoding format is selected for a
  particular FEC framework instance, it must be
  signaled to the receiver.
• Enables correct parsing by the recipient.

7
Solution DetailMulticasting of Config Information

• Session Announcement Protocol (SAP) RFC2974 is
  used to signal the FEC Framework Configuration
  Information (FFCI).
• FEC sender acts as the SAP announcer
• FEC receiver acts as the SAP listener
• SAP messages are sent UDP over IP to a well known
  UDP port (9875) and at least one well known
  multicast group IP address.
• IPv4 239.16.33.254 (admin scope) or
  224.2.127.254 (global scope)
• IPv6 FF0?0000027FFE
• IP TTL and DSCP values of SAP messages may be set
  by the sender.
• FEC sender doesnt need to maintain any state per
  receiver.

8
Multicasting of Config InformationSender
Procedure

• FEC sender periodically signals the FFCI for each
  FEC Framework instance available at the sender
• FFCI is placed in the SAP payload
• of Announcement message

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 -------------
------------------- V1
ARTEC auth len msg id hash
------------------
--------------

originating source (32 or 128
bits)

-------------------------
------- optional
authentication data
....
---------------------
-----------
optional payload type
-- - - -
- - - - - -
0 - - - - - -
- - - - - - - - - - - - - - -


payload

-------------------
-------------

• The periodic interval is 1-200sec (range) with
  default60sec.
• Session can be deleted by SAP delete message or
  the purge-time expiry.

Updated
Purge time 3 x announcement interval.
See note.
9
Multicasting of Config InformationReceiver
Procedure

• FEC receiver obtains the FFCI for each FEC
  Framework Instance from the payload of the
  received SAP announcements.
• Creates an entry in the local SAP database,
• Passes the FFCI to the FEC Framework module.
• When a matching announcement is received the next
  time, the FEC receiver should reset the timer of
  the corresponding entry, to avoid it being
  purged.
• The purge time 3 x announcement interval.

10
Solution DetailUnicasting of Config Information

• No dedicated protocol proposed for unicasting.
• The proposal is to enable the individual
  application protocol such as SIP, RTSP etc. to
  convey the desire to use FEC and exchange FFCI.
• The offer/answer signaling, described in
  RFC3264, is commonly utilized by many
  application protocols.
• Either FEC sender or FEC receiver conveys the
  desire to use FEC, and once agreed, they can
  exchange the FFCI.
• The draft includes text to describe SIP, RTSP
  etc.
• Anything else?

11
Changes since the last version

• Changed the SAP announcement interval range from
  1-60mins to 1-200seconds.
• This avoids the corresponding (SAP) multicast
  state timing out in the routers.
• Updated the Acknowledgement section.
• Fixed few minor editorial issues.

12
Next Steps

• Request further review/feedback from the WG.
• Is anything else needed?
• Work towards the WGLC!

13
Unicasting of FEC Config InfoSample Example

• RTSP messages may include the FEC related
  information.
• RTSP already provides extensibility of the
  existing method with new parameters.
• This specification suggests requesting for the
  FEC protection options by including FEC
  Protection Required in the Require header of
  SETUP (method) request message.
• The requesting node (node1) may then send either
  the SETUP message without using the Require
  header, if the remote node didnt support the
  FEC protection, or a new SETUP message to
  request the selected FEC protection streams.

Node1-gtNode2 SETUP lt ... gt RTSP/1.0 CSeq
1 Transport ltomitted for simplicitygt Re
quire FEC Protections Required Node2-gtNode1 RTS
P/1.0 200 OK or RTSP/1.0 551 Option Not
supported CSeq 1 CSeq
1 Transport ltomitted for simplicitygt
FEC-Info ltomitted for simplicitygt
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FEC Framework Architecture
Application Layer (MPEG, RTSP etc.)
FEC Config
Transport Protocol (RTP, RTCP etc.)
FEC Framework
FEC Scheme
SAP
Transport Layer (UDP etc.)
Network Layer (IP)
Data Link Layer