IP Router Alert Considerations and Usage

The IP Router Alert Option is an IP option that alerts transit routersto 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 theIP Router Alert option. This document discusses security aspects andusage guidelines around the use of the current IP Router Alert option.Specifically, it provides recommendation against using the RouterAlert in the end-to-end open Internet as well as identify controlledenvironments where protocols depending on Router Alert can be usedsafely. It also provides recommendation about protection approachesfor Service Providers. Finally it provides brief guidelines for RouterAlert implementation on routers.