The exchange of routing protocol updates is used to ensure that routers using an Internal Gateway Protocol (IGP) in an Autonomous System (AS), or routers using an External Gateway Protocol (EGP) to interconnect such ASes, have a common view of the internal and external internetworking topology. Incorrect routing protocol updates could be injected into an AS, thus causing loss of service to some or all of an organisation, its partners and clients, or even to the complete Internet. To prevent malicious updates being used in such denial of service attacks, routing protocols have addressed the issues of identification and authentication of the source of updates. In this paper the author seeks to examine the measures taken to secure the routing update exchange process of the more common protocols. Keywords routing protocol updates, autonomous system, external gateway protocol, internal gateway protocol, exchange process, security.