IGP advanced task #2. ISIS

Topology:

 

Requirements:

1. Routers R1, R2 and R4 are on the same broadcast segment 10.0.0/24.
2. All routers are configure for ISIS area 49.0001 and system-is is 0000.0000.000X where X is the router number.
3. Configure the routers, such that only routers R1 and R2 form ISIS neighbor relationship.
4. Do not use authentication.

Solution:

Configuring ISIS adjacency-filter on routers R1 and R2 can achieve the required result.
Note that you need to make sure that either R1 or R2 are elected DIS on the segment.

R1:

!
clns filter-set FILTER permit 49.0001.0000.0000.0002.00
!
router isis TASK2
 net 49.0001.0000.0000.0001.00
!
interface Ethernet0/0
 ip address 10.0.0.1 255.255.255.0
 ip router isis TASK2
 isis priority 125
 isis adjacency-filter FILTER
!

R2:

!
clns filter-set FILTER permit 49.0001.0000.0000.0001.00
!
router isis TASK2
 net 49.0001.0000.0000.0002.00
!
interface Ethernet0/1
 ip address 10.0.0.2 255.255.255.0
 ip router isis TASK2
 ip ospf network point-to-point
 isis adjacency-filter FILTER
!