Preserving Topology Confidentiality in Inter-Domain Path Computation using a key based mechanism

Document Type Replaced Internet-Draft (individual)
Last updated 2011-01-10 (latest revision 2007-01-05)
Replaced by draft-ietf-pce-path-key
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


Multiprotocol Label Switching (MPLS) Traffic Engineering (TE) Label Switched Paths (LSPs) may be computed by Path Computation Elements (PCEs). Where the TE LSP crosses multiple domains, such as Autonomous Systems (ASs), the path may be computed by multiple PCEs that cooperate, with each responsible for computing a segment of the path. However, in some cases (e.g. when ASs are administered by separate Service Providers), it would break confidentiality rules for a PCE to supply a path segment to a PCE in another domain, thus disclosing internal topology information. This issue may be circumvented by returning a loose hop and by invoking a new path computation from the domain boundary LSR during TE LSP setup as the LSP enters the second domain, but this technique has several issues including the problem of maintaining path diversity. This document defines a mechanism to hide the contents of a segment of a path, called the Confidential Path Segment (CPS). The CPS may be replaced by a path-key that can be conveyed in the PCE Communication Protocol (PCEP) and signaled within in a Resource Reservation Protocol (RSVP) explicit route object.


Richard Bradford (

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