LAB: EIGRP Filtering with Administrative Distance

Requirements:

Configure administrative distance filtering on R6 so that it does not install
the route to R4’s Loopback0 network.

R6:
access-list 4 permit 150.1.4.0
!
router eigrp 100
distance 255 0.0.0.0 255.255.255.255 4

- 0.0.0.0 255.255.255.255 - any source

notes:
Like in the other IGP protocols, administrative distance can be set on a per-prefix basis in EIGRP. In this example the source address of the route is ignored by matching an address of 0.0.0.0 with the wildcard 255.255.255.255, while accesslist 4 matches the route to change the distance for. Since the AD value of 255 is “infinite”, the route in question cannot be installed in the routing table or the EIGRP topology.

before:

Rack1R6#show ip route 150.1.4.4
Routing entry for 150.1.4.0/24
Known via "eigrp 100", distance 90, metric 156160, type internal
Redistributing via eigrp 10, eigrp 100
Advertised by eigrp 10
Last update from 155.1.146.4 on FastEthernet0/0.146, 00:27:44 ago
Routing Descriptor Blocks:
* 155.1.146.4, from 155.1.146.4, 00:27:44 ago, via FastEthernet0/0.146
Route metric is 156160, traffic share count is 1
Total delay is 5100 microseconds, minimum bandwidth is 100000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 1

after:


Rack1R6#show ip route 150.1.4.4
% Subnet not in table

Rack1R6#show ip eigrp 100 topology 150.1.4.0 255.255.255.0
% IP-EIGRP (AS 100): Route not in topology table