Here is a good document with regards to Cisco's implementation: http://www.cisco.com/web/SK/expo2011/pdfs/IP_Fast_reroute_PeterPsenk.pdf
Per the way LFAs are calculated in the RFC per-link doesn't guarantee node protection but depending on the topology it can provide it. However a vendor may choose to calculate the per-link backup path to be a node-protecting one if they choose and the topology allows it. Per-prefix may result in different backup paths based on your topology for two prefixes which take the same next-hop during normal conditions. By default Cisco will try to make a per-prefix LFA bypass the next-hop node resulting in node protection. Juniper uses a more efficient implementation and only does per-prefix, but you can pick and choose whether or not you want link or node-link protection. Node-link just adds another step in making sure the path. Not sure abou the ALU implementation. Phil On 6/4/13 2:43 AM, "Dhamija Amit" <[email protected]> wrote: > > Hi > >Can some one help me in understanding the exact difference in IP FRR Per >Link and Per Prefix option , It's mention in some docs that coverage of >protected prefixes will be more in per prefix option , If we have per >link then all the prefixes learned through same link will be covered in >LFA computation then what else is left for any router the IGP prefixes >will be learned through some link and if link is protected means all >prefixes are protected then how can we say coverage is more in per prefix. > >I see some vendors Juniper , ALU doesn't supports per prefix option.Could >you please elaborate more on this. > >Thanks for help > >Regards >Amit Dhamija > >_______________________________________________ >cisco-nsp mailing list [email protected] >https://puck.nether.net/mailman/listinfo/cisco-nsp >archive at http://puck.nether.net/pipermail/cisco-nsp/ _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
