Whether an autonomous system (AS) needs packets routed within itself or to and from another AS, the quality of the information exchange is vital. Communicating edge routers need to have a crystal-clear window of insight into one another’s full reachability and routing information, and that process depends on Border Gateway Protocol (BGP).
Through BGP management, every essential bit of packaged information that needs to be transmitted from Point A to Point B can reach its destination and be interpreted successfully. Depending on whether the pathway that information packages travel involves just one or a pair of autonomous systems, the protocol is distinctly classified as either “internal” (iBGP) or “external” (eBGP).
The potential for different BGP configurations is vast, and the most ideal will depend on the specific needs of the system administrator.
Process of Operation
In a similar fashion to TCP/IP, BGP routing information relay is based in a client-server model of operation. Before the BGP transmission sequence can begin, the green light must first be given by a request from the client-server. After the server has received and recognized the client-server’s request, a line of communication can be established.
Every traveling packet is put through the standard routing table built into its BGP router of origin. In addition to the router table of the BGP router itself, there is also a matching router table on the router’s server that works in tandem with it; this separate table is called the routing information base (RIB).
Every time that there is an event in the network that affects its information, BGP records the occurrence and develops a newly refreshed routing table with the change taken into account.
Potential Benefits of BGP
Whatever settings have been established by the system administrator will determine BGP’s routing behavior. Through precise programming, the administrator can assign specific pathways for routing information to travel through the network with pinpoint precision.
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Well-configured BGP topology adheres to all of the rules that the network is built upon. In addition to its flexible adherence to diverse network rules, BGP also contributes to higher system stability.
Even in the event that one of the active pathways temporarily goes offline due to a sudden outage, a network with BGP management can quickly adapt to the outage and instantly delegate the task to another pathway with an active Internet connection. When every pathway is clear for transmission, BGP assures adherence to whatever traffic-traveling pattern should be undergone as specified by the administrator’s preferences.
Depending on the needs of the administrator, they may be especially appreciative of the fact that the RIB is capable of transmitting information from both internal and external peers. With its capability of communicating with both externally connected and internal peers, the RIB can continually update the routing table in accordance to any changes that may occur throughout the system.
Utility and Limitations
While it is versatile, Border Gateway Protocol is not programmed with any function that gives it the ability to run automatic discoveries. Before it can be fully operational, all peer-to-peer connections need to be manually programmed and established with matching codes.
BGP normally works with a default assignment scheme for a certain number of designated IP address, but with the optional use of classless interdomain routing (CIDR), additional IP addresses can be included in the network.