administrator has decided that it is beneficial for his customers to reach one
another. These peers advertise their customers' routes to one another. This
does not mean that they exchange their full Internet routing tables.
belong to the same autonomous system. These routers may use loopback
interfaces to provide greater reachability in the AS. This is possible because
an IGP can provide multiple routes to any given destination address if the
network has redundant or multiple links to each router. If one interface on
a router goes down, the TCP connection to the loopback address can be
maintained by using redundant interfaces.
other than BGP can be used to establish the TCP connection. The TCP con-
nection is made by a three-way handshake using a SYN, ACK, SYN
sequence. Once a TCP connection has been established, route information
can be exchanged.
loops in the network. To share route information among all iBGP routers,
you must establish a logical mesh, as shown in Figure 7.5. Routing informa-
tion is then exchanged only between routers who are members of this mesh.
RouterB can learn BGP networks only from RouterA. When RouterC sends
its BGP information, only its own information is sent. Routing information
learned from RouterA is not included.