Скачать или смотреть How to configure Cisco router for dual ISP with ISP1 primary and ISP2 backup

Hello everyone!

Today we can learn how to configure Cisco router for dual ISP with ISP1 primary and ISP2 backup.

We have ip address 100.100.100.2/30 on interface FastEthernet0/0 to ISP1

and ip address 200.200.200.2/30 on interface FastEthernet0/1 to ISP2.

Local network with 192.168.1.0/24 subnet connecting to GigabitEthernet1/0 interface of router.

For the local network running DHCP server on Cisco router. (DHCP preconfigured)

Remote server for checking has ip address 5.5.5.5

So let's go!

1. Router#configure terminal

Router(config)#interface gigabitethernet1/0

Router(config-if)#ip address 192.168.1.1 255.255.255.0

Router(config-if)#ip nat inside

Router(config-if)#no shutdown

Router(config-if)#exit

Router(config)#interface fastethernet0/0

Router(config-if)#ip address 100.100.100.2 255.255.255.252

Router(config-if)#ip nat outside

Router(config-if)#no shutdown

Router(config-if)#exit

Router(config)#interface fastethernet0/1

Router(config-if)#ip address 200.200.200.2 255.255.255.252

Router(config-if)#ip nat outside

Router(config-if)#no shutdown

Router(config-if)#exit

2. Router(config)#route-map FOR_ISP1 permit 10 --this route-maps define interface for particular ISP

Router(config-route-map)#match interface fastethernet 0/0

Router(config-route-map)#exit

Router(config)#route-map FOR_ISP2 permit 10

Router(config-route-map)#match interface fastethernet 0/1

Router(config-route-map)#exit

3. Router(config)#ip sla 10

Router(config-ip-sla)#icmp-echo 5.5.5.5 source ip 100.100.100.2 --it's pings for checking reachability ISP1

Router(config-ip-sla-echo)#frequency 10 --define interval of pings

Router(config-ip-sla-echo)#exit

Router(config)#ip sla schedule 10 start-time now life forever --it starts our sla now and will be running forever

Router(config)#track 1 ip sla 10 --starting tracking of our sla 10

Router(config-track)#delay up 10 down 10 --timeout intervals for tracking

Router(config-track)#exit

4. Router(config)#ip route 0.0.0.0 0.0.0.0 100.100.100.1 track 1 --this route will be in route table when ip sla is working

Router(config)#ip route 0.0.0.0 0.0.0.0 200.200.200.1 2 --this route when ISP1 is unreachable

5. Router(config)#ip nat inside source route-map FOR_ISP1 interface FastEthernet0/0 overload

Router(config)#ip nat inside source route-map FOR_ISP2 interface FastEthernet0/1 overload

Router(config)#ip nat translation timeout 10 -- clearing nat translation table in 10 seconds

Router(config)#end

Router#write

Thank you. See you around.