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Faster method for recovery using global protection in MPLS networks

IP.com Disclosure Number: IPCOM000131943D
Original Publication Date: 2005-Dec-25
Included in the Prior Art Database: 2005-Dec-25
Document File: 2 page(s) / 28K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

Since MPLS (Multi Protocol Label Switching) has become on of the major techniques for provisioning and managing core networks, special emphasis has to be put on the questions of protection and recovery of these types of networks. In general, a network has to deal with the problem of finding a backup path, if the originally supposed network path failed in forwarding the message. Local Protection and Global Protection are the two types in which MPLS based protection can be categorized. In case of local protection, the switch over to the backup path is performed by the Label Switch Router (LSR) that will immediately upstream of the point of failure. The global protection will perform the switch over by the pre-determined LSR which is known as Path Switch LSR (PSL). The PSL is usually distant from the point of failure. So far, in Global Protection protocol implementations over Ethernet networks, no failure propagation method has been used. This leads to the case that connection failure will only be detected after a TE-RSVP (TE, Traffic Engineering; RSVP, Resource Reservation Protocol) path message is sent and no reservation message is received from the end Label Edge Router (LER). Depending on the configuration of the system, the detection could take seconds or possibly minutes before recovery actions can be initiated at the end nodes of the affected LSP (Label Switch Path).

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Faster method for recovery using global protection in MPLS networks

Idea: Paulo Ferreira, PT-Lisbon; Carlos Silva, PT-Lisbon

Since MPLS (Multi Protocol Label Switching) has become on of the major techniques for provisioning and managing core networks, special emphasis has to be put on the questions of protection and recovery of these types of networks. In general, a network has to deal with the problem of finding a backup path, if the originally supposed network path failed in forwarding the message. Local Protection and Global Protection are the two types in which MPLS based protection can be categorized. In case of local protection, the switch over to the backup path is performed by the Label Switch Router (LSR) that will immediately upstream of the point of failure. The global protection will perform the switch over by the pre-determined LSR which is known as Path Switch LSR (PSL). The PSL is usually distant from the point of failure. So far, in Global Protection protocol implementations over Ethernet networks, no failure propagation method has been used. This leads to the case that connection failure will only be detected after a TE-RSVP (TE, Traffic Engineering; RSVP, Resource Reservation Protocol) path message is sent and no reservation message is received from the end Label Edge Router (LER). Depending on the configuration of the system, the detection could take seconds or possibly minutes before recovery actions can be initiated at the end nodes of the affected LSP (Label Switch Path).

Up to now, the most used mechanisms for providing fast recovery on MPLS networks has been the Fast Reroute (FRR) technology which provides a function that protects the users' traffic by rapidly switching (several milliseconds) to a preset alternate route when link or node failures occur in the backbone network. To achieve this, a local protection approach is used, in which each node or link has a reserved protection. With this, no propagation of the failure to the LER is needed.

The basic idea to solve the time and complexity problems arising from the existing techniques is to provide the LSRs with the ability to propagate a failure on its nodes back to the LER. This can be done by sending a RSVP message from the detecting LSR to the LER. In "Resource Reservation Protocol" (Internet Engineering Task Force: RFC2205, Univ. of Michigan, September 1997) the functioning and classification of RSVP messages is described, in detail. The RSVP message is a path error message that has an object type like ERROR_SPEC Class (class = 6 and C-type = 1 or 2, depending if we are using IPv4 or IPv6; see Appendix A of RFC2205). This message also contains an error code that ranges from 1 to 23 and determines what kind of error has occurred (see Appendix B of RFC2205 for error codes and values). This invention proposes a new error code = 24: Global Path Error. The message will be sent in an IP packet to the LER. The IP address of the LER for a specific LSP has...