Chapter 5, Problem P15P

a)

Explanation of Solution

Path selected by “I”:

The “I” will be equal to “I₁” because this interface leads the least cost path form the 1d towards the gateway router “1c”...

b)

Explanation of Solution

Usage of AS-PATH:

Routers utilize AS-PATH attribute to identify and inhibit looping advertisements. It has a list of AS which helps in selecting among multiple paths available to the same prefix. In order to generate the AS-PATH, a prefix is passed to an AS. After passing the prefix, the AS adds its ASN to the existing list in the AS-PATH.

Usage of NEXT-HOP:

The NEXT-HOP attribute specifies the IP address of the first router which includes the advertised path to a given prefix...

c)

Explanation of Solution

Path selected by “I”:

Let us consider that another “AS” named AS5 is attached in between the path “AS2” and “AS4”.

• The router “1d” can accessible “x” thro...