Consider the entries shown below in the forwarding table of an IP router. Each entry consists of an IP prefix and the corresponding next hop router for packets whose destination IP address matches the prefix. The notation “/N” in a prefix indicates a subnet mask with the most significant N bits set to 1. This router forwards 20 packets each to 5 hosts. The IP addresses of the hosts are 10.1.1.16, 10.1.1.72, 10.1.1.132, 10.1.1.191, and 10.1.1.205 . The number of packets forwarded via the next hop router R2 is ________

To determine the next hop for each host IP address, we use the Longest Prefix Match (LPM) rule among the routing table entries:

• Prefix $10.1.1.0/24$: covers addresses $10.1.1.0$ to $10.1.1.255$ $\rightarrow$ Next hop: R1

• Prefix $10.1.1.128/25$: covers addresses $10.1.1.128$ to $10.1.1.255$ $\rightarrow$ Next hop: R2

• Prefix $10.1.1.64/26$: covers addresses $10.1.1.64$ to $10.1.1.127$ $\rightarrow$ Next hop: R3

• Prefix $10.1.1.192/26$: covers addresses $10.1.1.192$ to $10.1.1.255$ $\rightarrow$ Next hop: R4

Now, evaluate each destination host IP:

1. $10.1.1.16$:

   • Matches: $/24$

   • Longest match: $/24 \rightarrow$ R1

2. $10.1.1.72$:

   • Matches: $/24$, $/26$ ($10.1.1.64/26$)

   • Longest match: $/26 \rightarrow$ R3

3. $10.1.1.132$:

   • Matches: $/24$, $/25$ ($10.1.1.128/25$)

   • Does not match $10.1.1.192/26$

   • Longest match: $/25 \rightarrow$ R2

4. $10.1.1.191$:

   • Matches: $/24$, $/25$ ($10.1.1.128/25$)

   • Does not match $10.1.1.192/26$

   • Longest match: $/25 \rightarrow$ R2

5. $10.1.1.205$:

   • Matches: $/24$, $/25$, $/26$ ($10.1.1.192/26$)

   • Longest match: $/26 \rightarrow$ R4

Hosts forwarded via R2 are $10.1.1.132$ and $10.1.1.191$ (a total of $2$ hosts).

Since $20$ packets are sent to each host: