Editing Dynamic routing

{{Short description|A router process}}
{{More citations needed|date=December 2009}} 
In [[computer networking]], '''dynamic routing''' ('''DR'''), also called '''adaptive routing''' ('''AR'''),<ref>
Terrence Mak; Peter Y. K. Cheung; Kai-Pui Lam; and Wayne Luk.
[http://www.doc.ic.ac.uk/~wl/papers/11/tie11tm.pdf "Adaptive Routing in Network-on-Chips Using a Dynamic-Programming Network"].
2011.
{{doi | 10.1109/TIE.2010.2081953}}
p. 1.
</ref><ref>
{{cite journal|first1=Diego|last1=Lugones|first2=Daniel|last2=Franco|first3=Emilio|last3=Luque|title=Dynamic Routing Balancing On InfiniBand Networks|journal=Journal of Computer Science and Technology|volume=8|issue=2|year=2008|archive-date=6 May 2015|archive-url=https://web.archive.org/web/20150506055433/http://journal.info.unlp.edu.ar/journal/journal23/papers/JCST-Jul08-8.pdf|url=http://journal.info.unlp.edu.ar/journal/journal23/papers/JCST-Jul08-8.pdf}}
</ref>
is a process where a router can forward data via a different route for a given destination based on the current conditions of the communication circuits within a system.<ref>Haiyong Xie; [[Lili Qiu]]; Yang Richard Yang; and Yin Zhang.
[http://www-net.cs.yale.edu/publications/XQYZ04.pdf "On Self Adaptive Routing in Dynamic Environments — An Evaluation and Design Using a Simple, Probabilistic Scheme"] {{Webarchive|url=https://web.archive.org/web/20110902190331/http://www-net.cs.yale.edu/publications/XQYZ04.pdf |date=2011-09-02 }}.
2004.</ref> The term is most commonly associated with [[data networking]] to describe the capability of a network to 'route around' damage, such as loss of a node or a connection between nodes, as long as other path choices are available.<ref>{{Cite web | url = https://www.pcmag.com/encyclopedia/term/42195/dynamic-routing | title = Definition of | publisher = PC}}</ref> Dynamic routing allows as many routes as possible to remain valid in response to the change.

Systems that do not implement dynamic routing are described as using [[static routing]], where routes through a network are described by fixed paths. A change, such as the loss of a node, or loss of a connection between nodes, is not compensated for. This means that anything that wishes to take an affected path will either have to wait for the failure to be repaired before restarting its journey, or will have to fail to reach its destination and give up the journey.<ref>{{Cite web | url = https://technet.microsoft.com/en-us/library/cc957844.aspx | title = Static and Dynamic Routers | publisher = TechNet}}</ref>

==All protocols==
There are several [[routing protocols]] that can be used for dynamic routing. [[Routing Information Protocol]] (RIP) is a [[distance-vector routing protocol]] that prevents [[Routing loop problem|routing loops]] by implementing a limit on the number of [[Hop (telecommunications)|hops]] allowed in a path from source to destination.<ref>{{Cite web|url=http://www.techrepublic.com/article/dynamic-routing-with-rip/|title=Dynamic routing with RIP|publisher=Tech Republic}}</ref> [[Open Shortest Path First]] (OSPF) uses a [[link-state routing protocol|link state routing]] (LSR) algorithm and falls into the group of [[interior gateway protocol]]s (IGPs).<ref name=NetworkComputing/> [[Intermediate System to Intermediate System]] (IS-IS) determines the best [[routing|route]] for data through a [[packet-switched network]].<ref name=NetworkComputing/> [[Interior Gateway Routing Protocol]] (IGRP) and its advanced form [[Enhanced Interior Gateway Routing Protocol]] (EIGRP) are used by [[Router (computing)|router]]s to exchange [[routing]] data within an [[autonomous system (Internet)|autonomous system]].<ref name=NetworkComputing>{{Cite web|url=http://www.networkcomputing.com/data-centers/comparing-dynamic-routing-protocols/1562576794|title=Comparing Dynamic Routing Protocols|publisher=Network Computing}}</ref>

== Alternate paths ==
Many systems use some [[hop (networking)#Next hop|next-hop]] forwarding protocol—when a packet arrives at some node, that node decides on-the-fly which link to use to push the packet one hop closer to its final destination.

Routers that use some adaptive protocols, such as the [[Spanning Tree Protocol]], in order to "avoid [[bridge loop]]s and [[routing loop]]s", calculate a tree that indicates the one "best" link for a packet to get to its destination.
Alternate "redundant" links not on the tree are temporarily disabled—until one of the links on the main tree fails, and the routers calculate a new tree using those links to route around the broken link.

Routers that use other adaptive protocols, such as '''grouped adaptive routing''', find a group of ''all'' the links that could be used to get the packet one hop closer to its final destination.
The router sends the packet out any link of that group which is idle.
The [[link aggregation]] of that group of links effectively becomes a single high-bandwidth connection.<ref>
Stefan Haas.
[http://inspirehep.net/record/887357/files/cer-002474543.pdf "The IEEE 1355 Standard: Developments, Performance and Application in High Energy Physics"].
1998.
p. 91.
</ref>

==Outside of computer networks==
Dynamic routing in found the [[brain]] in relation between sensory and mnemonic signals and decision making, and is a subject of studies in [[neuroscience]].<ref>{{Cite web|url=http://www.nature.com/neuro/journal/v18/n2/full/nn.3918.html|title=Dynamic routing of task-relevant signals for decision making in dorsolateral prefrontal cortex|publisher=Nature}}</ref>

==See also==
* [[Convergence (routing)]]
* [[InfiniBand]]
* [[Routing in delay-tolerant networking]]

==References==
{{Reflist}}

==External links==
*[https://www.networkworld.com/article/957735/session-based-routing-holds-the-key-to-the-internets-future.html Session-based routing holds the key to the Internet’s future]

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[[Category:Routing]]