Constrained Shortest Path First (CSPF) is an extension of shortest path algorithms. The path computed using CSPF is a shortest path fulfilling a set of constraints. It simply means that it runs shortest path algorithm after pruning those links that violate a given set of constraints. A constraint could be minimum bandwidth required per link (also known as bandwidth guaranteed constraint), end-to-end delay, maximum number of links traversed, include/exclude nodes. CSPF is widely used in MPLSTraffic Engineering[citation needed]. The routing using CSPF is known as Constraint Based Routing (CBR).
The path computed using CSPF could be exactly same as that of computed from OSPF and IS-IS, or it could be completely different depending on the set of constraints to be met.
Example with bandwidth constraintedit
An Example network
Consider the network to the right, where a route has to be computed from router-A to the router-C satisfying bandwidth constrained of x- units, and link cost for each link is based on hop-count (i.e., 1).
If x = 50 units then CSPF will give path A → B → C.
If x = 55 units then CSPF will give path A → D → E → C.
If x = 90 units then CSPF will give path A → D → E → F → C.
In all of these cases OSPF and IS-IS will result in path A → B → C.
However, if the link costs in this topology are different, CSPF may accordingly determine a different path. For example, suppose that as before, hop count is used as link cost for all links but A → B and B → C, for which the cost is 4. In this case:
If x = 50 units then CSPF will give path A → D → E → C.
If x = 55 units then CSPF will give path A → D → E → C.
If x = 90 units then CSPF will give path A → D → E → F → C.
constrained, shortest, path, first, this, article, multiple, issues, please, help, improve, discuss, these, issues, talk, page, learn, when, remove, these, template, messages, this, article, includes, list, references, related, reading, external, links, source. This article has multiple issues Please help improve it or discuss these issues on the talk page Learn how and when to remove these template messages This article includes a list of references related reading or external links but its sources remain unclear because it lacks inline citations Please help improve this article by introducing more precise citations December 2022 Learn how and when to remove this template message This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Constrained Shortest Path First news newspapers books scholar JSTOR December 2022 Learn how and when to remove this template message Learn how and when to remove this template message Constrained Shortest Path First CSPF is an extension of shortest path algorithms The path computed using CSPF is a shortest path fulfilling a set of constraints It simply means that it runs shortest path algorithm after pruning those links that violate a given set of constraints A constraint could be minimum bandwidth required per link also known as bandwidth guaranteed constraint end to end delay maximum number of links traversed include exclude nodes CSPF is widely used in MPLS Traffic Engineering citation needed The routing using CSPF is known as Constraint Based Routing CBR The path computed using CSPF could be exactly same as that of computed from OSPF and IS IS or it could be completely different depending on the set of constraints to be met Example with bandwidth constraint edit nbsp An Example networkConsider the network to the right where a route has to be computed from router A to the router C satisfying bandwidth constrained of x units and link cost for each link is based on hop count i e 1 If x 50 units then CSPF will give path A B C If x 55 units then CSPF will give path A D E C If x 90 units then CSPF will give path A D E F C In all of these cases OSPF and IS IS will result in path A B C However if the link costs in this topology are different CSPF may accordingly determine a different path For example suppose that as before hop count is used as link cost for all links but A B and B C for which the cost is 4 In this case If x 50 units then CSPF will give path A D E C If x 55 units then CSPF will give path A D E C If x 90 units then CSPF will give path A D E F C References editZiegelmann Mark 2007 Constrained Shortest Path and Related Problems Constrained Network Optimization VDM Verlag Dr Muller ISBN 978 3 8364 4633 4 Retrieved from https en wikipedia org w index php title Constrained Shortest Path First amp oldid 1130571593, wikipedia, wiki, book, books, library,
