1. Network Coding Architecture Framework
Victor Firoiu, Brian Adamson
with inputs from Vincent Roca, Morten Pedersen
IETF

2. Network Coding Building Blocks
Reliability Functional Area
Congestion Control Functional Area
Block
Sliding Window
Back pressure?
Coding Functional Area
NACK
Null Space Sample
Random Linear
Deterministic
TFMCC?
TCP-CC
Knowledge vector
Non-linear
Others
What CC specific to NC?
Non-end-end feedback
End-to-end feedback
Security
Protocol Instantiations
Dragoncast
NORM-NC
no recoding
NCTCP
Tetrys
CONCERTO/BRAVO
NC sub-transport shim
FECFrameV2
NORM-NC
w recoding
Others..

3. NC Architecture/ Framework Document
Goals:
Identify building blocks to be defined in separate documents
And uncover open research questions
Identify interactions between BBs, new functionalities to research
E.g.: what Congestion control function is needed specific to NC?
Outline a path toward a small set of protocol instantiations – for future standardization

4. Backup Material

5. RMT Building Block Approach
Building Blocks
Reliability Functional Area
Congestion Control Functional Area
TRACK*
GRA*
PGMCC*
Coding Functional Area
FEC
NACK
TFMCC
WEBRC
LCT
Raptor, etc
Reed Solomon
LDPC
Security
NORM
ALC
Protocol Instantiations
Applications
FCAST
FLUTE
* Unrealized building blocks

6. Use Case 1: NC Shim Layer – under TCP, UDP, SSH
App
App
TCP
TCP
App data
Congestion signal,
Recv window
NC shim
NC shim
Coding vectors, coded pkts
Feedback (rank, null space)
NC Reliability
NC Reliability
Coded symbols,
Rank test
Cong signal,
backpressure
NC Coding
NC Cong Ctrl
NC Cong Ctrl
NC Coding
Rate control
NC Forwarding
NC Forwarding
Security IP IP IP
Unicast Routing
Unicast Routing
Unicast Routing
Coding: end-end. Passes CC signaling.
Optional: in-network re-coding.
Coding nodes determined by: static configuration, routing or control signaling.
Usage: reliability, similar to source coding.
Security is a key building block factor – impacts all other BBs

7. Use Case 2: NC Transport, In-Network Coding
App
App
App data
FlowID, blockID
Coding vectors,
Feedback
NC Transport
NC Transport
NC Transport
NC Reliability
NC Rel
NC Reliability
Coded symb,
Rank test
Rate control
Cong. signals
NC Coding
NC Cong Ctrl
NC Cod
NC CC
NC Cong Ctrl
NC Coding
NC Forwarding
NC Forwarding
NC Forwarding
Pkts containing coded symbols
Security
(Multi-path) Routing
(Multi-path) Routing
(Multi-path) Routing IP IP IP IP
Usage: reliability, resilience to link and node outage.
Supports both Unicast and Multicast
Assisted by multi-path (subgraph) routing
Security is a key building block factor – impacts all other BBs

8. Network Coding Architecture: Functional Areas View
Coding – all coding operations
Encoding, decoding, test for “innovative”, rank, null space
Uses operations such as finite field and linear transformations
Reliability – algo & control for rel. transp.
Rel. logic: block, window, end-to-end, hop- by-hop
Ctrl: coding info (vectors, ID), feedback.
Forwarding – Tx/Rx coded pkts
Pkt Tx logic: next hop, when to Tx
Ctrl: SG topo, splitting ratios/ fwd factors
Cong Control – control of Tx rates
Ucast, mcast, subgraph <research!>
May use existing CC BB: TFRC [5348] for unicast, TFMCC [4654] for mcast.
Source (app) data pkts
Flow ID, block ID,
Coding vectors, Feedback
NC Transport
NC Reliability
Coded symb,
Rank test
Cong. signals
NC Cong Ctrl
NC Coding
Rate control
Coded pkts,
Splitting ratios
NC Forwarding
Security
Routes, mcast/SG topo, neighbors, link quality
(Multi-path) Routing
Considerations - Research
Security: how to add encr, vulnerability
Complexity, energy
Heterogeneity

9. NC Coding Functional Area
Function: coding operations
Code/decode, test for block/gen rank, null space, window oper.
Test for innovative/ linear indep.
Interfaces with Reliability FA
Request/provide coded/decoded symbols, block/window rank,
No outside control
NC Reliability
Code/decode symbols
Rank test, null/range space, test for innovative
NC Coding

10. NC Reliability Functional Area
Function: Reliable transport
Rel. logic: block, window, end-end/hop-hop
Manages flow of data/symbols between App, Coding, Fwd FAs
Control: to Rel FA in peer nodes
Session: Flow ID, encoding type/ID, symbol size
Coding info: vectors, ID
Feedback: Block: rank/deg freedom/Null Space Sample; Window: high/low index
Interface w Forwarding FA
Gets Tx opportunity
Provides coded symbols for Tx
Interface w Coding FA
Requests coded/decoded symbols, req tests for rank, innovative
App
QoS/Reliability level
Source (app) data pkts
Flow ID, block ID,
Coding info, feedback
NC Reliability
Code/ decode symbols
Rank test, null/range space, test for innovative
Tx opportunity,
Coded symbols
NC Coding
NC Forwarding

11. NC Forwarding Functional Area
Function: Tx/Rx coded pkts
Pkt Tx logic: next hop: neighbor nodes, when to Tx from what flow
Allocates flow slices to paths
Measures netw conditions: loss, delay
Control: w Fwding FAs in peer nodes
Coordinate info flow allocation in multi- path/tree/subgraph: splitting ratios/ fwd factors
Data plane: Tx/Rx pkts w coded symbols
Interface w Congestion Control FA
Provides cong indications (loss, delay), gets Tx rate limit
Interface w routing
Gets ucast/mcast/SG topology
NC Reliability
NC Cong Ctrl
Tx opportunity,
Coded symbols
Coded pkts,
Splitting ratios
Rate control
NC Forwarding
Routes, mcast/SG topo, neighbors, link quality
(Multi-path) Routing

12. NC Congestion Control Functional Area
Function: control of Tx rates to avoid congestion and follow TCP-friendly recommendations
Ucast, mcast, subgraph <research!>
May use existing CC BB: TFRC [5348] for unicast, TFMCC [4654] for mcast
Control: w CC FA in peer nodes
Congestion signals: backpressure, ECN, sliding window size
Interface w Fwding FA
Gets cong measurements
Gives Tx rate limit
Cong. signals: backpressure, ECN
NC Cong Ctrl
Cong measurements
Rate control
NC Forwarding

13. NC Security Functional Area
Security Considerations:
How to add encryption: independent of coding or inter-changeable (e.g., homomorphic)
How to identify vulnerabilities
Different security mechanisms may apply to different FAs
Needs to be applied consistently across this complex system
NC Transport
Coding vectors, Feedback
NC Reliability
Coded symb,
Rank test
Cong. signals
NC Cong Ctrl
NC Coding
Rate control
Coded pkts
Splitting ratios
NC Forwarding
Security

14. Next Steps Draft on NC Architecture and Building Blocks
Later, may need to split into separate BB drafts
Try to reuse as much as possible: e.g., CC BB: TFRC [5348] for unicast, TFMCC [4654] for mcast
Show how a simple protocol can be built with these building blocks