The Creation of Border Gateway Protocol

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Border Gateway Protocol (BGP), being a dynamic routing protocol, exchanges routes between BGP neighbors, which is sometimes called “peers”. The main aim behind the creation of this protocol was to expand and replace Exterior Gateway Protocol (EGP).
Occasionally, BGP is described as a reachability protocol rather than a routing protocol.
BGP is a Path Vector Protocol (PVP), which aims at maintaining paths to different hosts, networks and gateway routers and determines the routing decision based on that. It does not use Interior Gateway Protocol (IGP) metrics for routing decisions, but only decides the route based on path, network policies and rule sets. Actually, BGP was intended to route within an Autonomous System (AS), but rather to route between AS’s. In opposition to popular opinion, when multiple connections to the Internet are required, BGP is not a necessity. IGP can easily handle fault tolerance and redundancy of outbound traffic, such as OSPF or EIGRP. BGP is also totally unnecessary if there is only one connection to an external AS (such as the Internet). There are over 100,000 routes on the Internet, though interior routers should not be needlessly burdened. BGP should be used under the following circumstances:
• Multiple connections exist to external AS’s (such as the Internet) via different providers.
• Multiple connections exist to external AS’s through the same provider, but connect via a separate CO or routing policy.
• The existing routing equipment can handle the additional demands.
BGP’s true advantage is in managing how traffic enters the local AS, rather than how traffic exits it. Network security wasn't an issue, when BGP was developed. When it started really taking hold among the varying ISPs around the worl...

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...n IP prefix, it would be easy to verify in case it had the right to do so. The solution would authenticate only the first hop in a route to prevent unintentional hijacks, like Pakistan Telecom’s, but wouldn’t stop an eavesdropper from hijacking the second or third hop. In order to prevent preceding hops it requires BGP routers to digitally sign with a private key any prefix advertisement they propagated. An
ISP would give peer routers certificates authorizing them to route its traffic; each peer on a route would sign a route advertisement, forwarding it to the next authorized hop. The drawback of this solution is that current routers lack the memory and processing power to generate and validate signatures. And router vendors have resisted upgrading them because their clients, ISPs, haven’t demanded it, due to the cost and the hours involved in swapping out routers.

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