Imagine WAN connections of an enterprise network running on the AT&T's PSDN as follows.

-What IP address-Virtual Circuit mapping information would R1 need to maintain to deliver packets to R2 and R3?
$\begin{array}{|ll|c|}
\hline &{\text { IP address of }} & \text {Virtual circuit} \

&{\text { Destination Routers }} & \text { Identifier } \
\hline \text { (1) } & 10.10 .10 .2 & \text { VC1 } \
\text { (2) } & 10.10 .10 .2 & \text { VC2 } \
\text { (3) } & 172.16 .10 .2 & \text { VC3 } \
\text { (4) } & 172.16 .10 .2 & \text { VC4 } \
\text { (5) } & 192.168 .10 .1 & \text { VC5 } \
\text { (6) } & 192.168 .10 .1 & \text { VC6 } \
\hline
\end{array}$
A) (1) and (2)
B) (1) and (3)
C) (1), (3), and (5)
D) (1), (2), (3), and (4)
E) (1), (2), (3), (4), (5) and (6)

Question

Imagine WAN connections of an enterprise network running on the AT&T's PSDN as follows.
 
-What IP address-Virtual Circuit mapping information would R1 need to maintain to deliver packets to R2 and R3?
$\begin{array}{|ll|c|}
\hline &{\text { IP address of }} & \text {Virtual circuit} \

&{\text { Destination Routers }} & \text { Identifier } \
\hline \text { (1) } & 10.10 .10 .2 & \text { VC1 } \
\text { (2) } & 10.10 .10 .2 & \text { VC2 } \
\text { (3) } & 172.16 .10 .2 & \text { VC3 } \
\text { (4) } & 172.16 .10 .2 & \text { VC4 } \
\text { (5) } & 192.168 .10 .1 & \text { VC5 } \
\text { (6) } & 192.168 .10 .1 & \text { VC6 } \
\hline
\end{array}$
A) (1) and (2) 
B) (1) and (3) 
C) (1), (3), and (5) 
D) (1), (2), (3), and (4) 
E) (1), (2), (3), (4), (5) and (6)

Quizplus · Accepted Answer

R1 only needs to maintain the IP address-Virtual Circuit mapping information for the routers that are directly connected to it. In this case, R2 and R3 are directly connected to R1 through Virtual Circuits VC1, VC2, VC3, and VC4. Therefore, R1 only needs to maintain the IP address-Virtual Circuit mapping information for (1) and (3).

Imagine WAN Connections of an Enterprise Network Running on the AT&T's