Scenario
EIGRP uses variance for load-balancing and distribute-lists (IOS) and route-policies (XR) for filtering. This section covers a simple setup with an EIGRP configured router filtering a couple of /30 transit links and with variance configured for load-balancing.
IOS Config
hostname R1 ! router eigrp 10 variance 2 network 10.10.12.0 0.0.0.3 network 10.10.42.0 0.0.0.3 network 192.168.50.0 passive interface GigabitEthernet1/0 distribute-list prefix BLOCK_TRANSIT_LINKS in no auto-summary eigrp router-id 2.2.2.2 ! ip prefix-list BLOCK_TRANSIT_LINKS seq 5 deny 10.10.13.0/30 ip prefix-list BLOCK_TRANSIT_LINKS seq 10 deny 10.10.43.0/30 ip prefix-list BLOCK_TRANSIT_LINKS seq 50 permit 0.0.0.0/0 le 32 ! interface GigabitEthernet0/0 description link to R2 ip address 10.10.12.2 255.255.255.252 speed 100 full-duplex ! interface GigabitEthernet0/1 description link to R4 ip address 10.10.42.2 255.255.255.252 speed 100 full-duplex ! interface GigabitEthernet0/2 description Local LAN ip address 192.168.50.1 255.255.255.0 speed 100 full-duplex |
XR Config
hostname R1 ! interface GigabitEthernet0/0/0/0 description link to R2 ipv4 address 10.10.12.2 255.255.255.252 speed 100 duplex full ! interface GigabitEthernet0/0/0/1 description link to R4 ipv4 address 10.10.42.2 255.255.255.252 speed 100 duplex full ! interface GigabitEthernet0/0/0/2 description Local LAN ipv4 address 192.168.50.1 255.255.255.0 speed 100 duplex full ! prefix-set BLOCK_TRANSIT_LINKS 10.10.13.0/30, 10.10.43.0/30 end-set ! route-policy TRANSIT_FILTER if destination in BLOCK_TRANSIT_LINKS then drop else pass endif end-policy ! router eigrp 10 address-family ipv4 router-id 2.2.2.2 variance 2 route-policy TRANSIT_FILTER in ! interface GigabitEthernet0/0/0/0 ! interface GigabitEthernet0/0/0/1 ! interface GigabitEthernet0/0/0/2 passive-interface ! ! ! |