Slide Notes

Title

Name is Alvar Penning
Here on behalf of the Distributed Systems Group, UMR
Present DTN7: An Open-Source Disruption-tolerant Networking Implementation of Bundle Protocol 7

DTN

Even nowadays lots of situations without a reliable uplink
- Environmental monitoring, destroyed or censored infrastructure
Example: sensor on the top, sink bottom's right hand side; no celluar network
DTN now! Delay / Disruption-tolerant Networking
- Store-carry-forward instead of a continous connection stream
- Message goes hop-by-hop - whenever possible
- Not time critical

DTN7

Such a DTN software is DTN7
FOSS
Golang: memory safe, compiles to many targets
Modularized design, esay to extend; exchangable components
Implements BP7

BP7

DTN architecture and network protocol
Active development, draft 14 released 2 months ago
- However, it was version 13 before
Aims to obsolete older BP6

Nodes and Endpoints

Nodes are identified by an EID, URI
Nodes might be addressed by multiple EIDs
EID might address multiple Nodes; Multicast
Explain example

Bundles and Blocks

Packets called Bundles: sequence of blocks
Concise Binary Object Representation (CBOR)
Example: multiple Blocks in Bundle
Example: Primary Block
- Destination, Source as IP
- Ctrl Flags and Report-To for delivery / forwarding
Example: Canonical Blocks
- Other blocks are of the same structure
- Identified by type code
- Hop Count / Previous Node / ...
Example: Payload Block
- Last block
- Contains Bundle's payload / the message

Bundle Exchange

Exchange between two nodes has 2 sides: Transport and Routing
Transport is CL
- Currently TCP (MTCP, TCPCL)
- Everything is possible
Routing
- DTLSR, Spray and Wait, Epidemic
- More is comming

Other DTN components

Store on each node; for store-carry-forward
RESTful API to create and fetch Bundles
- Easy from any programming language / curl / wget
Peer Discovery on UDP multicast
- Creates CL link between neighboring nodes

DTN7 Programs

Daemon dtnd for DTN
Command line companion tool dtncat for RESTful API

DTN7 Architecture

Short explaination

Evaluation

Used CORE, Linux namespace containers
Up to 64 nodes in chain - pairwise connected as in illustration
To not measure CPU, limited link to 54 MBit/s - simulation of IEEE 802.11g
Range of payload sizes from 64 KiB - 100 MiB; assigned representing labels
Created competition to other DTN/DTN-like software
- DTN7
- Forban: HTTP exchange
- IBR-DTN: BP6
- Serval: custom DTN protocol

Results

2 and 64 nodes
IBR-DTN and DTN7 are fastest
Best for small files; big files saturizes bandwith limitation

CPU/Network

Full satuation
Low CPU load