The Path Computation Element (PCE) provides path computation
functions in support of traffic engineering in Multi-Protocol Label
Switching (MPLS) and Generalized MPLS (GMPLS) networks. A limited
form of statefulness is useful to improve PCE functionality in
situations in which the local TED might not be up to date, or in the
case of concurrent requests where most of the LSPs are computed
before the end of the set-up of the LSPs when the TED is updated. The
PCE can retain some context from the resources assigned to Path
Requests during a certain period of time, so that it avoids
suggesting the use of the same resources for subsequent TE LSPs.
This document proposes an extension to the PCEP protocol to allow the
PCC to request the PCE to block or reserve the resources computed in
a path request of a TE LSP for subsequent requests for a certain
time.