Path Computation in Multiple Autonomous Systems Networks with Path Computation Element
draft-xia-pce-hybrid-network-00

Abstract

The Path Computation Element (PCE) provides functions of path computation in support of traffic engineering in Multi-Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS) networks. One key application of the PCE-based architecture is the computation of inter-domain Traffic Engineering Label Switched Path (TE-LSP) paths(i.e. inter-area, inter-AS, inter-provider, etc.). In this case, cooperation between PCEs is desirable due to the partial topology visibility available to each separate PCE. Per-domain path computation is another method that can be used to determine paths for inter-domain TE-LSPs when PCE cooperation is not applied in the network. In practice, some Service Providers may choose not to implement PCEs within their network that can cooperate with PCEs that are outside their network. In this case, a scenario may exist where an LSP spans multiple autonomous systems (ASes), some of which have PCEs capable of cooperation with external PCEs and some of which do not. For example, some ASes may be PCE-enabled, while others consist of just normal LSRs. Another scenario arises if a PCE fails or becomes unreachable. This gives rise to the same lack of inter-PCE cooperation. Both cases are named Hybrid PCE Networks in this document. This document describes the specific issues introduced for end-to-end path computation in Hybrid PCE Networks and defines extensions to the PCE Communication Protocol (PCEP) to perform inter-domain LSP computation in Hybrid PCE Networks.

Authors

Hongmiao Xia
Dan Li

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