End To End Recovery (Ip-Layer); End To End Ecmp - Alcatel-Lucent 7450 Manual

Ethernet service switch

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The following subsections detail some example recovery options that are possible using either

GMPLS, or a combination of GMPLS mechanisms and mechanisms in the overlay IP network.

Note that some of the functionality shown in one of the scenarios can be used in combination with

functionality in another scenario, for example optical SRLG diversity.

The objective of GMPLS here is to minimize the disruption to the overlay IP network while

simultaneously maximizing the utilization of both the gLSPs and the resources in the underlying

optical network (or UNI links).

End to End Recovery (IP-layer)

End to end recovery applies to protection against failures at any point along the entire path

between a local UNI-C and a far end UNI-C. In the context of the GMPLS UNI, recovery can be

implemented in the overlay IP network either at Layer 3 or Layer 2, with assistance from the

underlay optical network, with optional additional protection and/or restoration of gLSPs by

UNI-C nodes. Each gLSP is bound to a separate IP network interface at the UNI-C. RSVP

signaling across the UNI is used to ensure that the gLSPs are SRLG diverse (by explicitly

signaling the SRLG list to avoid in an XRO for every gLSP, or automatically collecting the SRLG

list for a gLSP which does not have an XRO, and then signaling a subsequent gLSP including this

collected list in its XRO). Protection is provided at the IP layer by hashing across the IP network

interfaces associated with each gLSP. The operational state of each IP interface can be tied to the

operational state of its gLSP (controlled using RSVP) or using mechanisms in the IP overlay such

7450 ESS MPLS Guide

Optical Segment — Between 1830 PSS UNI-N nodes at each edge of the optical network.

illustrates the first model. Multiple gLSPs are established between a pair of remote