BGP Connection Establishment

BC

BGP (Border Gateway Protocol) is a routing protocol used to exchange routing information between different Autonomous Systems (AS) on the Internet. It uses TCP (Transmission Control Protocol) as its underlying transport protocol and follows a TCP three-way handshake mechanism to establish a connection between BGP peers.

To establish a BGP connection, the following two conditions must be met:

1. AS number on local router: The local router must have a unique Autonomous System (AS) number assigned to it, which identifies it as a member of a specific AS. This number is configured on the local router using the "router bgp" command followed by the AS number.

For example, if the AS number of the local router is 100, the configuration command would be:

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router bgp 100 

2. AS number on remote router: The remote router must also have a unique Autonomous System (AS) number assigned to it, which identifies it as a member of a specific AS. This number is typically obtained from a Regional Internet Registry (RIR) or an Internet Service Provider (ISP).

The AS number of the remote router is configured on the local router using the "neighbor" command followed by the IP address of the remote router and its AS number.

For example, if the IP address of the remote router is 192.168.1.1 and its AS number is 200, the configuration command would be:

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neighbor 192.168.1.1 remote-as 200 

Note that the other answer choices listed in the question are not relevant to the establishment of a BGP connection:

• CDP ( Cisco Discovery Protocol) is a Cisco proprietary protocol used to discover information about directly connected Cisco equipment, and it is not required for BGP.
• IGP (Interior Gateway Protocol) is a routing protocol used to exchange routing information within a single Autonomous System, and it is not relevant to BGP, which is used to exchange routing information between different AS.
• EGP (Exterior Gateway Protocol) is an outdated routing protocol used to exchange routing information between different AS, and it has been replaced by BGP.