Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. The proposed extensions present no backward compatibility issues. Such an approach reduces computational complexity and the associated signalling overhead. Referring to Figure 1, there is an MPLS network consisting of 7 interconnected switches.
Arrows indicate direction of the data traffic.
The dashed line between switches 5 and 1 illustrates such a segment of the alternative path. The initial and final segments of the alternative path are linked to form an entire alternative path from the last hop switch to the destination switch. As soon as a link failure or congestion along the protected path is detected an operational switch at ingress of failed link reroutes incoming traffic around of the failure or congestion by linking upstream portion of the primary path to the downstream portion of the alternative path. Procedures similar to the creation of the primary LSP can be used to establish this disjoint segment. When this flag is set, all transit LSRs set up an alternate LSP based on the mechanism specified in this document.