network's routers
Consider the three-node network below, that uses flow-based generalized forwarding (e.g., as in OpenFlow) in the network's routers. In the question below, we'll want to create match+action entries in the flow table at router r2, with three ports labelled 1,2,3 (in black). In the question, matches are constrained to be over only four fields: the IP source address, the IP destination address, the upper-layer protocol field of the IP datagram, and the destination port number of the transport-layer segment. The actions are either to drop or to forward(i), that is, to forward a matching packet on port i. The default action (unless stated otherwise) is that if a packet doesn't match a rule, it will be dropped.
Question: Suppose we want to implement the following rule: r2 should act as a firewall, only allowing TCP traffic into the 22.33/16 network from any network. Specify a single flow table row entry to implement this rule, indicating the column entries for the row below. The * is a wildcard match, which matches everything.
![In the "source IP" column, the flow table entry should be:
In the "dest. IP" column, the flow table entry should be:
In the "protocol" column, the flow table entry should be:
In the "action" column, the flow table entry should be:
[Choose ]
[Choose]
TCP
UDP
forward(2)
*
forward(3)
22.33/16
128.119/16
drop
53.106/16
forward(1)](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F10e465a6-7588-4fdb-8c02-7922f29b53b5%2Fada47be1-be5f-4870-8fc4-201a3c9c0135%2Ffwvskzj_processed.png&w=3840&q=75)
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for the 'action' column, why it is 'forward(2)' but not 'forward(3)'? Could you explain it for me?
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