At the end of this task, any router loopback interface should have connectivity to any other router loopback in the topology.
Only use ISIS routing protocol. No other protocols, including static routing are allowed.
R1 and R4 should be configured in ISIS area 49.0013.
R3 should be configured in ISIS area 49.0004.
Configure R2 to allow full connectivity between all devices in the topology
The solution is to configure R2 for ISIS Multihoming. Multihoming allows merging two ISIS areas into single area, by configuring multiple NET values under same ISIS process. Note that System-ID should be identical.