The Cost of Loop Free Alternates in IP-over-WDM Networks
Date: Wed, December 18, 2013
Time: 10:30 - 11:30am
Location: Holmes Hall 389
Speaker: Ciril Rozic, PhD student, University of Hawaii, Department of Electrical Engineering
Loop-free Alternates (LFA) is a method for protecting traffic in the IP layer. With LFAs, for each primary route, the router also has an alternate, which is used after a failure such as a fiber-link cut or an IP link failure. This ensures that traffic can resume in less than 50 ms after a failure is detected. This is unnecessary for traditional services such as FTP and e-mail, but it is useful for applications that are very delay-sensitive. The LFA routing may require extra link capacity in the network, which in turn results in extra network cost. We show algorithms to design IP-over-WDM networks that eventually restore all, and fast-protect a fraction of the original traffic after a failure, while minimizing the cost. The results show that 50% of the original traffic between every pair of routers can be protected by LFAs at almost no additional cost.