These restoration mechanisms allow backup paths, onto which traffic can be quickly redirected upon failure detection, to be setup simultaneously with the active path thus ensuring that an U P if set-up is quickly restorable upon failure. The incorporation of restoration leads to a new QoS routing problem where it is necessary to dynamically route both an active path and a backup path in order to satisfy a request to set-up a restorable bandwidth guaranteed UP. Simultaneous routing of both paths ensures that sufficient resources will be available upon failure for succesful LSP restoration. Simultaneously established backup paths also aid fast restoration by elimination path computation and path set-up signaling delays. In this paper, we present new algorithms for the problem of setting up bandwidth guaranteed tunnels with backup. Since we are focusing on the MPLS application, we use the terms LSP and tunnels synonymously in the rest of the paper. We concentrate on bandwidth routing because this is the most likely traffic engineering use for setting up QoS guaranteed paths. If QoS constraints such as delays and losses are to be incorporated in service level agreements (SLA), one way of accomodating this, given the traffic descriptor and SLA, is to convert such an SLA into an effective bandwidth requirement for the U P S (with the queueing delays and losses primarily restricted to the network edges) which can then be routed through the MPLS network as a constant-bit-rate stream encountering only negligible or predictable queueing delays in the MPLS core network. Routing taking delay and loss metrics directly into account is difficult computationally and requires information difficult to acquire such 8s nodal load versus delay characteristics. The problem is further compounded when backup paths have to routed as well. Note that an approach essentially similar to routing of bandwidth guaranteed paths can be used for dynamic wavelengthpath set-up in optical networks @articularly when wavelength conversion is permitted at each optical crossconnect). Here a wavelength can be thought of as the outermost (non-stackable) label in the MPLS label stack. These functional similarities between setting-up wavelength switched paths and setting-up 0-7803-5880-5/0a/$10.00 ( c ) 2000 IEEE 902 IEEE INFOCOM 2000
Kodialam and Lakshman REF proposed bandwidth guaranteed dynamic routing algorithms.
Dynamic routing of bandwidth guaranteed tunnels with restoration
Proceedings IEEE INFOCOM 2000. Conference on Computer Communications. Nineteenth Annual Joint Conference of the IEEE Computer and Communications Societies (Cat. No.00CH37064)
Proceedings IEEE INFOCOM 2000. Conference on Computer Communications. Nineteenth Annual Joint Conference of the IEEE Computer and Communications Societies (Cat. No.00CH37064)
Computer Science