Path-vector routing protocol: Difference between revisions
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{{Short description|Routing algorithm | {{Short description|Routing algorithm for packet switched networks}} | ||
A '''path-vector routing protocol''' is a network [[Routing protocol|routing protocol]] which maintains the path information that gets updated dynamically. Updates that have looped through the network and returned to the same node are easily detected and discarded. This algorithm is sometimes used in [[Bellman–Ford algorithm|Bellman–Ford routing algorithms]] to avoid "Count to Infinity" problems. | A '''path-vector routing protocol''' is a network [[Routing protocol|routing protocol]] which maintains the path information that gets updated dynamically. Updates that have looped through the network and returned to the same node are easily detected and discarded. This algorithm is sometimes used in [[Bellman–Ford algorithm|Bellman–Ford routing algorithms]] to avoid "Count to Infinity" problems.<ref>{{Cite web |title=Lecture 04 |url=https://www.cse.iitb.ac.in/~br/webpage/courses/cs625-fall2003/lec-notes/lec-notes04-2.html |access-date=2026-02-03 |website=Department of Computer Science and Engineering, Indian Institute of Technology Bombay}}</ref> | ||
It is different from the distance vector routing and link state routing. Each entry in the routing table contains the destination network, the next router and the path to reach the destination. | It is different from the distance vector routing and link state routing. Each entry in the routing table contains the destination network, the next router and the path to reach the destination. | ||
''[[Border Gateway Protocol]]'' (BGP) is an example of a path vector protocol. In BGP, the [[Open Shortest Path First#Autonomous system boundary router|autonomous system boundary routers]] (ASBR) send path-vector messages to advertise the reachability of networks. Each router that receives a path vector message must verify the advertised path according to its policy. If the message complies with its policy, the router modifies its routing table and the message before sending the message to the next neighbor. It modifies the routing table to maintain the [[Autonomous system (Internet)|autonomous systems]] that are traversed in order to reach the destination system. It modifies the message to add its AS number and to replace the next router entry with its identification. | ''[[Border Gateway Protocol]]'' (BGP) is an example of a path vector protocol.<ref>{{Cite book |last=Goralski |first=Walter |title=The Illustrated Network: How TCP/IP Works in a Modern Network |date=25 November 2008 |publisher=Morgan Kaufmann |year=2008 |isbn=978-0128110270 |pages=418-419}}</ref> In BGP, the [[Open Shortest Path First#Autonomous system boundary router|autonomous system boundary routers]] (ASBR) send path-vector messages to advertise the reachability of networks. Each router that receives a path vector message must verify the advertised path according to its policy. If the message complies with its policy, the router modifies its routing table and the message before sending the message to the next neighbor. It modifies the routing table to maintain the [[Autonomous system (Internet)|autonomous systems]] that are traversed in order to reach the destination system. It modifies the message to add its AS number and to replace the next router entry with its identification. | ||
''[[Exterior Gateway Protocol]]'' (EGP) does not use path vectors. | ''[[Exterior Gateway Protocol]]'' (EGP) does not use path vectors. | ||
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# Updating | # Updating | ||
BGP is commonly referred to as an Exterior Gateway Protocol (EGP) given its role in connecting Autonomous Systems (AS). | |||
Communication protocols within AS are therefore referred to as | Communication protocols within AS are therefore referred to as Interior Gateway Protocols (IGP) which contain [[Open Shortest Path First|OSPF]] and [[IS-IS]] among others. | ||
This being said, BGP can be used within an AS, which typically occurs within very large organizations such as Facebook or Microsoft. | This being said, BGP can be used within an AS, which typically occurs within very large organizations such as Facebook or Microsoft. | ||
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==See also== | ==See also== | ||
* [[Link-state routing protocol]] | * [[Link-state routing protocol]] | ||
==References== | |||
{{reflist}} | |||
{{DEFAULTSORT:Path Vector Protocol}} | {{DEFAULTSORT:Path Vector Protocol}} | ||
[[Category:Routing protocols]] | [[Category:Routing protocols]] | ||
{{Sourceattribution|Path-vector routing protocol}} | {{Sourceattribution|Path-vector routing protocol}} | ||
Latest revision as of 13:35, 14 April 2026
A path-vector routing protocol is a network routing protocol which maintains the path information that gets updated dynamically. Updates that have looped through the network and returned to the same node are easily detected and discarded. This algorithm is sometimes used in Bellman–Ford routing algorithms to avoid "Count to Infinity" problems.[1]
It is different from the distance vector routing and link state routing. Each entry in the routing table contains the destination network, the next router and the path to reach the destination.
Border Gateway Protocol (BGP) is an example of a path vector protocol.[2] In BGP, the autonomous system boundary routers (ASBR) send path-vector messages to advertise the reachability of networks. Each router that receives a path vector message must verify the advertised path according to its policy. If the message complies with its policy, the router modifies its routing table and the message before sending the message to the next neighbor. It modifies the routing table to maintain the autonomous systems that are traversed in order to reach the destination system. It modifies the message to add its AS number and to replace the next router entry with its identification.
Exterior Gateway Protocol (EGP) does not use path vectors.
It has three phases:
- Initiation
- Sharing
- Updating
BGP is commonly referred to as an Exterior Gateway Protocol (EGP) given its role in connecting Autonomous Systems (AS).
Communication protocols within AS are therefore referred to as Interior Gateway Protocols (IGP) which contain OSPF and IS-IS among others.
This being said, BGP can be used within an AS, which typically occurs within very large organizations such as Facebook or Microsoft.
See also
References
- ↑ "Lecture 04". https://www.cse.iitb.ac.in/~br/webpage/courses/cs625-fall2003/lec-notes/lec-notes04-2.html.
- ↑ Goralski, Walter (25 November 2008). The Illustrated Network: How TCP/IP Works in a Modern Network. Morgan Kaufmann. pp. 418-419. ISBN 978-0128110270.
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