The default IS-IS network type is point-to-point so a DIS is not elected

A DIS is elected between the IS-IS neighbors and the elected DIS is pre-empted if router with a higher system ID is connected

The area, levels, and interface MTU parameters must match, and system MTU must be unique for two IS-IS routers to become adjacent

Faster IS-IS hello and dead timers increase bandwidth and CPU use, and may cause instability

The IS-IS hello and dead timers should be tuned to detect failures as quickly as possible

A DIS is elected between the IS-IS neighbors and the elected Dis is pre-empted if a router with a lower system ID is connected

The hello and dead timers must match for two IS-IS routers to become adjacent

It is dropped due to an unsuccessful RPF check against the multicast receiver

It is switched due to a successful RPF check against the routing table

It is switched given that no RPF check is performed

It is dropped due to an unsuccessful RPF check against the multicast source

Security

Time to deploy

Inefficiency

Reduced operational overhead

Resource consumption