LAB: EIGRP Filtering with Offset Lists

Requirements:

- Configure an offset-list on SW1 so traffic destined for R3’s Loopback0
network is sent to R6.
- If the link to R6 is down traffic should be rerouted directly to R3.

SW1:
router eigrp 100
offset-list 1 in 2147483647 FastEthernet0/3
!
access-list 1 permit 150.1.3.0


- offset parameter will both add up to the FD/AD metrics ( this is additive in nature)

tip: if you want 2 different metrics to be in the routing table you can use this method, subtract the higher metric with lower metric and use the result as the offset value. to make it equal.

Note:

Like in RIP, the offset-list feature in EIGRP is used to modify the metric on a perroute basis or a per-interface basis. Before any metric modifications we can see that SW1 is routing directly to R3 to reach 150.1.3.0/24. There are no additional entries in the EIGRP topology table for this prefix since both R6 and SW3 are routing through SW1 to reach it.

before:

Rack1SW1#show ip route 150.1.3.3
Routing entry for 150.1.3.0/24
Known via "eigrp 100", distance 90, metric 130560, type internal
Redistributing via eigrp 100
Last update from 155.1.37.3 on FastEthernet0/3, 02:16:47 ago
Routing Descriptor Blocks:
* 155.1.37.3, from 155.1.37.3, 02:16:47 ago, via FastEthernet0/3
Route metric is 130560, 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
Rack1SW1#show ip eigrp topology 150.1.3.0 255.255.255.0
IP-EIGRP (AS 100): Topology entry for 150.1.3.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 130560
Routing Descriptor Blocks:
155.1.37.3 (FastEthernet0/3), from 155.1.37.3, Send flag is 0x0
Composite metric is (130560/128000), Route is Internal
Vector metric:
Minimum bandwidth is 100000 Kbit
Total delay is 5100 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 1

after:

Rack1SW1#show ip eigrp topology 150.1.3.0 255.255.255.0
IP-EIGRP (AS 100): Topology entry for 150.1.3.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is
25742592
Routing Descriptor Blocks:
155.1.67.6 (Vlan67), from 155.1.67.6, Send flag is 0x0
Composite metric is (25742592/142592), Route is Internal
Vector metric:
Minimum bandwidth is 1544 Kbit
Total delay is 1005570 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 3
155.1.37.3 (FastEthernet0/3), from 155.1.37.3, Send flag is 0x0
Composite metric is (2147614207/2147611647), Route is Internal
Vector metric:
Minimum bandwidth is 100000 Kbit
Total delay is 83891179 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 1