Assume host A and host B are connected with each other via two routers, and three links as illustrated below. Link$1$ and Link$3$ are each $1$ km$,$ Link$2$ is $100$ km $.$ The bandwidth of Link$1$ and Link$3$ are both $100$Mbps$,$ and the bandwidth of Link$2$ is $1$Gbps$.$ Both Router$1$ and Router$2$ are store$-$and$-$forward routers. The propagation speed over the three links is $3$x$108$ m$/$s$.$