1. IETF#67 – 5-10 November 2006 FECFRAME requirements (draft-ietf-fecframe-req-01)
Mark Watson

2. Changes since IETF66 Add “motivation” section
Why define a new Framework instead of using RMT’s FEC Building Block and RMT FEC Schemes directly ?
Reasons:
Some FEC Object Transmission Information will be the same for every block of the flow - RMT FEC BB doesn’t include concept of multiple related objects
RMT FEC Schemes include recommendations for setting FEC parameters - we need a place for different recommendations for the streaming case
We need a place to define formatting of stream data into blocks for processing by the FEC code
Proposal:
The FEC Framework is a “peer” to the RMT FEC Building Block
FEC Schemes for use with the FEC Framework may be different from those for use with the RMT FEC BB
Minor editorial/cleanup

3. Next steps More review or WGLC ? Is this the right level of detail ?
What other issues need to be addressed ?

4. IETF#67 – 5-10 November 2006 FECFRAME proposal (draft-watson-fecframe-framework-00)
Mark Watson

5. Application protocols FEC Streaming Framework
Architecture
Content Delivery Protocol
Definition of flows to be protected and flow to carry protection data
Rules/indications for source data partitioning/timing
Application
Application protocols
(RTP, RTCP, MIKEY etc.)
Allocates packets to source blocks
Constructs and sends source and repair packets
FEC Streaming Framework
FEC Scheme
Transport (e.g. UDP)
Provides encoding and decoding of FEC data.
Defines and interprets FEC signaling elements (Object Transmission Information, FEC Payload IDs) IP

6. Proposal outline
Follows 3GPP streaming framework with generalised of source block concept
Defines:
Division of responsibility between
FEC Framework
FEC Schemes
Content Delivery Protocols
General procedures and packet format for FEC source and FEC repair packets
Includes possibility of unmodified source packets to support fully backwards-compatible FEC Schemes
FEC Framework Configuration Information
Includes SDP elements which MAY be used by Content Delivery Protocols for communicating this information
Congestion control requirements

7. Generalisation of source block concept
FEC Framework arranges packets into “source blocks” for encoding by the FEC Scheme
3GPP
Source block is a sequence of fixed length “symbols”
Padding added by FEC Framework to each packet so that packets start on symbol boundaries
Symbols are passed to FEC Scheme for encoding/decoding
New draft proposal
Source block is a sequence of tuples { flowid, packet length, packet payload }
FEC Scheme defines construction of FEC symbols

8. Advantages of generalisation
Accommodate wider range of FEC Schemes
FEC Schemes compatible with 3GPP still possible
Associates concept of “symbols” with FEC Scheme

9. Division of responsibilities
FEC Framework
Identifies packet flows which are to be protected
Groups source packets into source blocks
Interacts with FEC Scheme
FEC Scheme
Mapping from source block -> repair packets (encoding)
Mapping from source/repair packets -> source block (decoding)
Encoding and interpretation of FEC Object Transmission Information and FEC Payload IDs
Content Delivery Protocol
Encode and communicate FEC Configuration Information (definition of flows and flow ids)

10. Procedures and packet format
Descriptions taken mainly from 3GPP framework
Source Packets
Repair Packets
IP header
Transport header
Transport payload
FEC Payload ID
IP header
Transport header
FEC repair data
FEC Payload ID

11. FEC Framework Configuration Information
FEC Framework Configuration information consists of the following things:
Definition of the IP flows that are protected
i.e. standard source/destination address/port tuple
Definition of short flow IDs for each flow
Used to refer to flows on interface between FEC Scheme and FEC Framework
Definition of IP flow for repair data
We define SDP elements which MAY be used by CDPs to communicate this information

12. Congestion control Text taken from original proposal to TSVWG
Bandwidth of repair MUST NOT exceed bandwidth of the protected source
Repair bandwidth MUST be adapted when source bandwidth is adapted
Actual congestion control algorithm is a matter for the source flow

13. Next steps
Comments ?
Other proposals ?
Accept as WG document ?