Associativity-based routing: Difference between revisions

Revision as of 03:45, 26 November 2016

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while doing his Ph.D. at Cambridge University. In the 1990s, our Internet is still largely wired. Toh was working on a different

Internet - that of a rapidly deployable, self-organizing, self-configuration mobile Internet. The challenges in such a network

is mobility of nodes and link dynamics. Toh's prime argument is that there is no point in choosing a node to route packets if the route is unstable or going to be broken soon. So, he introduced a new routing metric (known as associativity ticks) and the concept of associativity, i.e., link stability among nodes over TIME and SPACE. Hence, ABR was born.

is mobility of nodes and link dynamics.

Toh's prime argument is that there is no point in choosing a node to route packets if the route is unstable or going to be broken

soon. So, he introduced the concept of associativity, i.e., link stability among nodes over TIME and SPACE. Hence, ABR was born.

==Explanation==

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==AR Route Deletion Phase==

When a discovered route is no longer needed, a RD (Route Delete) packet will be initiated by the source node

so that all intermediate nodes in the route will update their routing table entries and stopped relay data

packets associated with this deleted route.

In addition to using RD to delete a route, ABR can also implement a soft state approach where route entries

are expired or invalidated after timed out, when there is no traffic activity related to the route over a

period of time.

==ABR Practicality==

In 1998, ABR was successfully implemented into Linux kernel, in various different branded laptops (IBM Thinkpad,

COMPAQ, Toshiba, etc) that are equipped with WaveLAN 802.11a PCMCIA wireless adapters. A working 5-node campus wide

[[wireless ad hoc network]] was achieved and the field trial was published in Mobile Computing Magazine in 1999.

Various tests were performed with the network:

[1] Transmission of up to 100MBytes of data from source to destination over 3-hop route.

[2] Link breaks and automatic link repairs proven to be working

[3] Automatic Route Discovery

[4] Route Delete

[5] Web Server in Ad Hoc mode - with source being client and destination being the web server

[6] Transmission of multimedia information (audio and video)

[7] TELNET over Ad Hoc

[8] FTP over Ad Hoc

[9] HTTP over Ad Hoc

Also, network performance measurements on the following were made:

[1] End-to-end delay

[2] TCP throughput

[3] Packet loss

[4] Route discovery delay

[5] Route repair delay

==ABR Patent==

ABR was granted a US patent 5987011<ref>{{cite conference|url=https://www.google.com/patents/US5987011}}</ref> and

the assignee being [[King's College Cambridge]], UK. ABR was subsequently licensed to a US defense corporation.

Tactical Mobile Ad Hoc Networks bloom with US defense spending over $2Billion in programs and research by DARA,

DoD, Air Force, Coast Guards, and US Navy.

==ABR Descendants==

Quite a few other mobile ad hoc routing protocols have incorporated ABR's stability concept, such as signal

stability routing, associativity-based multicast routing, and so on. The stability concept is also applied

to [[wireless sensors networks]] and [[VANETs]] - Vehicular Ad Hoc Networks.