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Solano Donado, Fernando
Fabregat Gesa, Ramon Marzo i LÃ¡zaro, Josep LluÃs 

Most network operators have considered reducing Label Switched Routers (LSR) label spaces (i.e. the number of labels that can be used) as a means of simplifying management of underlaying Virtual Private Networks (VPNs) and, hence, reducing operational expenditure (OPEX). This letter discusses the problem of reducing the label spaces in Multiprotocol Label Switched (MPLS) networks using label merging  better known as MultiPointtoPoint (MP2P) connections. Because of its origins in IP, MP2P connections have been considered to have tree shapes with Label Switched Paths (LSP) as branches. Due to this fact, previous works by many authors affirm that the problem of minimizing the label space using MP2P in MPLS  the Merging Problem  cannot be solved optimally with a polynomial algorithm (NPcomplete), since it involves a hard decision problem. However, in this letter, the Merging Problem is analyzed, from the perspective of MPLS, and it is deduced that treeshapes in MP2P connections are irrelevant. By overriding this treeshape consideration, it is possible to perform label merging in polynomial time. Based on how MPLS signaling works, this letter proposes an algorithm to compute the minimum number of labels using label merging: the Full Label Merging algorithm. As conclusion, we reclassify the Merging Problem as Polynomialsolvable, instead of NPcomplete. In addition, simulation experiments confirm that without the treebranch selection problem, more labels can be reduced  
http://hdl.handle.net/2072/59033  
eng  
IEEE  
Tots els drets reservats  
Arbres (Teoria de grafs)
MPLS (Norma) Protocols de xarxes dâ€™ordinadors Computer network protocols MPLS standard Trees (Graph theory) Virtual Private Network 

On optimal computation of MPLS label binding for multipointtopoint connections  
info:eurepo/semantics/article  
Recercat 