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

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
`$C$`.