PCEP Extension for Stateful Inter-Domain Tunnels
Orange
Orange
The Path Computation Element (PCE) working group (WG) has produced a set of RFCs to standardize the behavior of the Path Computation Element as a tool to help MPLS-TE, GMPLS LSP tunnels and Segment Routing paths placement. This also include the ability to compute inter-domain LSPs or Segment Routing path following a distributed or hierarchical approach. In complement to the original stateless mode, a stateful mode has been added. In particular, the new PCInitiate message allows a PCE to directly ask a PCC to setup an MPLS-TE, GMPLS LSP tunnel or a Segment Routing path. However, once computed, the inter-domain LSPs or Segment Routing path are hard to setup in the underlying network. Especially, in operational network, RSVP-TE signaling is not enable between AS border routers. But, such RSVP-TE signaling is mandatory to setup contiguous LSP tunnels or to stitch or nest independent LSP tunnels to form the end-to-end inter-domain paths. This document proposes to combine a Backward Recursive or Hierarchical method with PCInitiate message to setup independent paths per domain, and combine these different paths together in order to operated them as end-to-end inter-domain paths without the need of signaling session between AS border routers. A new Stitching Label is defined and new LSP-TYPE code points are considered for that purpose.