The IESG has approved the following document: - 'Framework for Loop-free convergence using oFIB' (draft-ietf-rtgwg-ordered-fib-12.txt) as Informational RFC This document is the product of the Routing Area Working Group. The IESG contact persons are Adrian Farrel and Stewart Bryant. A URL of this Internet Draft is: http://datatracker.ietf.org/doc/draft-ietf-rtgwg-ordered-fib/ Technical Summary This document describes the framework of a mechanism for use in conjunction with link state routing protocols which prevents the transient loops which would otherwise occur during topology changes. It does this by correctly sequencing the forwarding information base (FIB) updates on the routers. This mechanism can be used in the case of non-urgent link or node shutdowns and restarts or link metric changes. It can also be used in conjunction with a fast re-route mechanism which converts a sudden link or node failure into a non-urgent topology change. This is possible where a complete repair path is provided for all affected destinations. After a non-urgent topology change, each router computes a rank that defines the time at which it can safely update its FIB. A method for accelerating this loop-free convergence process by the use of completion messages is also described. The technology described in this document has been subject to extensive simulation using real network topologies and costs, and pathological convergence behaviour. However mechanism described in this document are purely illustrative of the general approach and do not constitute a protocol specification. The document represents a snapshot of the work of the Routing Area Working Group at the time of publication and is published as a document of record. Further work is needed before implementation or deployment. Working Group Summary: No issues. There is consensus in the WG to proceed with publication. Document Quality: This document presents the general mechanism and operation of oFIB, it doesn't define routing protocol-specific extensions â?? which means that there are no implementations possible, but also no further work is planned at this time. The document has no substantive issues. Personnel: Alvaro Retana (aretana@cisco.com) is the Document Shepherd. Adrian Farrel (adrian@olddog.co.uk) is the Responsible Area Director. RFC Editor Note Please note that there are 6 authors on the front page. As noted in the Shepherd write-up, all six authors contributed substantially to the text and are active in the work of the document. There is no lead editor or editors. We would like to make an exception for this document and continue to list all 6 authors at the same level. --- In the Abstract s/the mechanism described/the mechanisms described/ --- Please insert a new paragraph as the second paragraph in Section 2... In this document, a distinction is made between urgent and non-urgent network events. Urgent events are those that arise from unpredictable network outages (such as node or link failures) that are traditionally resolved through the convergence of routing protocols or by protection mechanisms reliant on fault detection and reporting (such as through Operations, Administration, and Maintenance). Non-urgent events are those that arise from predictable events such as the controlled shut-down of network resources by a management system, or the modification of network parameters (such as routing metrics). Typically, non-urgent events can be planned around, while urgent events must be handled by dynamic systems. All network events, both urgent and non-urgent, may lead to transient packet loops and loss.
