The exhibit shows the configuration of RSTP on EX-4, which has the command  force-version stp .  This command forces the switch to use the legacy STP protocol instead of RSTP, even though the switch supports RSTP 1 .  This means that EX-4 will not be able to take advantage of the faster convergence and enhanced features of RSTP, such as edge ports, link type, and proposal/agreement sequence 2 .

The other switches in the network are likely to be running RSTP, as it is the default protocol for EX Series switches 3 . Therefore, there will be a compatibility issue between EX-4 and the other switches, which will result in longer convergence times and suboptimal performance.  The switch will also generate a warning message that says “Warning: STP version mismatch with neighbor” when it receives a BPDU from a RSTP neighbor 1 .

To solve this problem, the force-version command must be removed from EX-4, so that it can run RSTP natively and interoperate with the other switches in the network. This will enable faster convergence and better stability for the network topology.  To remove the command, you can use the  delete protocols rstp force-version  command in configuration mode 1 .

A. On R1, enable Level 1 on the ge-0/0/1 interface.  In IS-IS, both levels (Level 1 and Level 2) are enabled by default when you enable IS-IS on an interface 1 .  Level 1 systems route within an area 2 .  If the destination is outside an area, Level 1 systems route toward a Level 2 system 2 . Therefore, enabling Level 1 on the ge-0/0/1 interface on R1 would allow packets to reach from R1 to R3.

D. On R3 enable Level 1 on the ge-0/0/4 interface Similarly, enabling Level 1 on the ge-0/0/4 interface on R3 would allow packets to reach from R1 to R3.

These explanations are based on the IS-IS configuration documents and learning resources available at Juniper Networks 1  and Cisco 3 4 .

Option A is correct. Creating multiple areas in OSPF can help to reduce the convergence time . This is because changes in one area do not affect other areas, so fewer routers need to run the SPF algorithm in response to a change.

Option D is correct. Creating multiple areas in OSPF can help to reduce Link State Advertisement (LSA) flooding across the network. This is because LSAs are not flooded out of their area of origin.