Exploring the Trade-offs in Inter-AS LSPs Computation

Cristel Pelsser and Olivier Bonaventure

Technical Report 2005-13 November 2005

Abstract

MultiProtocol Label Switching (MPLS) is used inside large ISP networks to provide services with stringent Service Level Agreements such as Virtual Private Networks (VPNs). Customers are now urging ISPs to provide such services across interdomain boundaries. This requires the ability to establish interdomain MPLS Label Switched Paths (LSPs) with constraints. Up to now, the literature has mostly focused on mechanisms to compute LSPs inside a single AS. In this paper, we explore the fundamental trade-offs for the computation of interdomain LSPs with QoS guarantees. We first show how cooperative Path Computation Elements (PCE) can be used to establish such LSPs. Our simulations indicate that with cooperative PCEs, it is possible to find good paths, but this is at the cost of a large number of messages exchanged between PCEs. In addition, we observe that the routes known to BGP constitute the main limitation to obtain interdomain LSPs that compete in their QoS with those that could be found using the full topological information of the network. We then propose and evaluate two heuristics to select appropriate interdomain paths without requiring too many inter-PCE messages.

Publication Details

Publication Type
Technical Report
Publication Date
November 2005
Published In
Technical Report 2005-13

Suggested citation

Cristel Pelsser and Olivier Bonaventure. 2005. Exploring the Trade-offs in Inter-AS LSPs Computation. In Technical Report 2005-13.

BibTeX Citation

@techreport{Pelsser2005b,
	title        = {Exploring the Trade-offs in Inter-AS LSPs Computation},
	author       = {Pelsser, Cristel and Bonaventure, Olivier},
	year         = 2005,
	month        = nov,
	booktitle    = {Technical Report 2005-13},
	institution  = {Technical Report 2005-13},
	abstract     = {MultiProtocol Label Switching (MPLS) is used inside large ISP networks to provide services with stringent Service Level Agreements such as Virtual Private Networks (VPNs). Customers are now urging ISPs to provide such services across interdomain boundaries. This requires the ability to establish interdomain MPLS Label Switched Paths (LSPs) with constraints. Up to now, the literature has mostly focused on mechanisms to compute LSPs inside a single AS. In this paper, we explore the fundamental trade-offs for the computation of interdomain LSPs with QoS guarantees. We first show how cooperative Path Computation Elements (PCE) can be used to establish such LSPs. Our simulations indicate that with cooperative PCEs, it is possible to find good paths, but this is at the cost of a large number of messages exchanged between PCEs. In addition, we observe that the routes known to BGP constitute the main limitation to obtain interdomain LSPs that compete in their QoS with those that could be found using the full topological information of the network. We then propose and evaluate two heuristics to select appropriate interdomain paths without requiring too many inter-PCE messages.},
	groups       = {Technical reports},
	keywords     = {MPLS, interdomain routing, QoS}
}

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