Question

P16 Consider the following network. ISP B provides national backbone service to regional ISP A. ISP C provides national backbone service to regional ISP D. Each ISP consists of one AS. B and C peer with each other in two places using BGP. Consider traffic going from A to D. B would prefer to hand that traffic over to C on the West Coast (so that C would have to absorb the cost of carrying the traffic cross-country), while C would prefer to get the traffic via its East Coast peering point with B (so that B would have carried the traffic across the country). What BGP mechanism might C use, so that B would hand over A-to-D traffic at its East Coast peering point?

Answer 1

Solution :

Considering the following data :

$\text{ISP B}$ provides the national backbone to the regional $\text{ISP A}$.

$\text{ISP C}$ provides the national backbone to the regional $\text{ISP D}$.

Each of the ISP consists of one autonomous systems (AS).

$\text{ISP B}$ would like to hand over the traffic of C through the $\text{West}$ Coast.

The $\text{ISP C}$ would like to receive traffic from B's peering point via East Coast.

One way for $C$ to force $B$ to hand over all of $B$’s traffic to $D$ on the east coast is for $C$ to  only advertise its route to $D$ via its east coast peering point with $C$.