Transcript FEC framework Configuration Signaling draft-ietf-fecframe-config-signaling-00.txt IETF 72

FEC framework Configuration
Signaling
draft-ietf-fecframe-config-signaling-00.txt
IETF 72
Rajiv Asati
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draft-ietf-fecframe-config-signaling-00.txt
Agenda
• Motivation
• Solution
• Solution Overview
– Encoding Format
– Multicasting Method
– Unicasting Method
• Changes since the last version
• Next step
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draft-ietf-fecframe-config-signaling-00.txt
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) 1.
2.
3.
4.
5.
•
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 ?
draft-ietf-fecframe-config-signaling-00.txt
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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).
FEC_Sender2---------|
|--------FEC_Receiver2
|
|
FEC_Sender1-----IP/MPLS network
|-----------FEC_Receiver11
|-----------FEC_Receiver12
|-----------FEC_Receiver13
• Solution defines two signaling methods – Session Announcement Protocol for Multicasting
– Individual application protocol for Unicasting; No
dedicated protocol.
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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).
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Solution Detail
Encoding 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.
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Solution Detail
Multicasting 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?:0:0:0:0:0:2:7FFE
– IP TTL and DSCP values of SAP messages may be set by the sender.
• FEC sender doesn’t need to maintain any state per receiver.
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Multicasting of Config Information
Sender 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
Updat
ed
• The periodic interval* is 1200sec (range) with
default=60sec.
• Session can be deleted by
SAP delete message or the
purge-time expiry.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| V=1 |A|R|T|E|C|
auth len
|
msg id hash
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
:
originating source (32 or 128 bits)
:
:
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
optional authentication data
|
:
....
:
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
|
optional payload type
|
+
+-+- - - - - - - - - -+
|
|0|
|
+ - - - - - - - - - - - - - - - - - - - - +-+
|
|
|
:
payload
:
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Purge time = 3 x announcement interval.
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* See note.
draft-ietf-fecframe-config-signaling-00.txt
Multicasting of Config Information
Receiver 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.
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Solution Detail
Unicasting 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?
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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.
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Next Steps
• Request further review/feedback from the
WG.
– Is anything else needed?
• Work towards the WGLC!
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Unicasting of FEC Config Info
Sample 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.
Node1->Node2: SETUP < ... > RTSP/1.0
CSeq: 1
Transport: <omitted for simplicity>
Require: FEC Protections Required
Node2->Node1: RTSP/1.0 200 OK
CSeq: 1
Transport: <omitted for simplicity>
FEC-Info: <omitted for simplicity>
•
|
|
|
|
or |
|
RTSP/1.0 551 Option Not supported
CSeq: 1
The requesting node (node1) may then send either the SETUP message
without using the Require: header, if the remote node didn’t support the
“FEC protection”, or a new SETUP message to request the selected FEC
protection streams.
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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
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