IP Router Alert Considerations and Usage

The IP Router Alert Option is an IP option that alerts transit routers to more closely examine the contents of an IP packet. RSVP, PGM, IGMP/MLD, MRD and GIST are some of the protocols that make use of the IP Router Alert option. This document discusses security aspects and usage guidelines around the use of the current IP Router Alert option. Specifically, it provides recommendation against using the Router Alert in the end-to-end open Internet as well as identify controlled environments where protocols depending on Router Alert can be used safely. It also provides recommendation about protection approaches for Service Providers. Finally it provides brief guidelines for Router Alert implementation on routers.