An Architecture for splicing TE-LSPs in Hierarchical CsC scenarios
draft-balaji-mpls-csc-te-lsp-splice-02

Abstract

Hierarchical Carrier Supporting Carrier deployments involve a Carrier Core which hereinafter is called the Tier-1 provider and two or more VPN sites that are carriers themselves hereinafter called Tier-2 providers that offer MPLS VPN services to their own customers. In such cases normally LDP is used to distribute labels amongst the routers (P and PE devices) in the Tier-2 provider's sites. When RSVP based TE-LSPs are constructed to explicitly route traffic for Tier-2 ISP's customers from the Tier-2 PEs to the CE of the Tier-1 provider and such TE-LSPs exist on multiple sites of the Tier-2 provider, the Tier-2 ISP may require splicing together through an "auto-match-and- splice-together" facility such that traffic flows from the PE of the Tier-2 ISP through the TE-LSP onto the CE of the Tier-1 ISP and then onto the other site and takes a path through a specific TE-LSP from the CE of the other site to the destination Tier-2 PE and then onto the final customer. This solution offers a lot of advantages such as providing adequate assurance that the bandwidth for the traffic flowing through these spliced TE-LSPs is met. It also provides a explicit routing of the traffic rather than through the regular LDP (which follows IGP) scenarios. Such explicitly routed TE-LSPs would have been constructed taking into account factors such as using under-utilized links for example. Splicing together these TE-LSPs in various sites and doing the splicing on an auto-match based on bandwidth or delay metrics would be a good service to offer to the Tier-2 ISPs customers. This draft outlines a scheme that offers such a feature and service to the Tier-2 ISPs through the addition of certain additional label exchanges and some additional labels such as the RSVP-stitch label and the RSVP-splicing-LDP label in the label stack which can be used to splice together these tunnels. In case of re-optimization of the LSP end-to-end there is a wide variety of choices for the near-end PE to hook up with a suitable far-end tunnel in the other Tier-2 site. Explicit tunnel setup can be obviated by merely choosing from a set of already constructed tunnels based on criterion that may involve various parameters. Also fast-reroute in case of remote tunnel failure is taken care of.

Authors

Bhargav Bhikkaji
Balaji Venkat Venkataswami
Shankar Raman
Gaurav Raina

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)