03-26-2017 03:14 PM - edited 03-05-2019 08:15 AM
We have a Cisco 3925e router and we have two different ISPs connected. We have three WAN links from which ISP1 has a primary and backup link and ISP2 has just one primary link.
We load balance traffic between ISP1 and ISP2 and we want to configure failover if ISP1 primary link goes down and ISP2 link should work regardless. When ISP1 primary link goes down, the ISP1 backup link default route does not get injected in the routing table.
Please help us resolve this issue.
track 1 ip sla 1 reachability
!
track 2 ip sla 2 reachability
!
track 3 ip sla 3 reachability
!
interface GigabitEthernet0/0 (ISP1 Primary Link)
ip address 1.1.1.2 255.255.255.252
no ip redirects
no ip unreachables
no ip proxy-arp
ip flow ingress
ip virtual-reassembly in
ip verify unicast reverse-path
load-interval 30
duplex auto
speed auto
no cdp enable
no mop enabled
!
interface GigabitEthernet0/1 (ISP1 Backup Link)
ip address 2.2.2.2 255.255.255.252
no ip redirects
no ip unreachables
no ip proxy-arp
ip flow ingress
ip virtual-reassembly in
ip verify unicast reverse-path
load-interval 30
duplex auto
speed auto
no cdp enable
no mop enabled
!
interface GigabitEthernet0/2 (ISP2 Primary Link)
ip address 3.3.3.2 255.255.255.252
no ip redirects
no ip unreachables
no ip proxy-arp
ip flow ingress
ip virtual-reassembly in
ip verify unicast reverse-path
load-interval 30
duplex auto
speed auto
no cdp enable
no mop enabled
!
interface GigabitEthernet0/3
ip address 192.168.0.1 255.255.255.0
no ip redirects
no ip unreachables
no ip proxy-arp
ip flow ingress
ip virtual-reassembly in
ip verify unicast reverse-path
load-interval 30
duplex auto
speed auto
no cdp enable
!
ip route 0.0.0.0 0.0.0.0 1.1.1.1 track 1
ip route 0.0.0.0 0.0.0.0 3.3.3.1 track 3
ip route 0.0.0.0 0.0.0.0 2.2.2.1 10
!
ip sla 1
icmp-echo 1.1.1.1 source-interface GigabitEthernet0/0
ip sla schedule 1 life forever start-time now
ip sla 2
icmp-echo 2.2.2.1 source-interface GigabitEthernet0/1
ip sla schedule 2 life forever start-time now
ip sla 3
icmp-echo 3.3.3.1 source-interface GigabitEthernet0/2
ip sla schedule 3 life forever start-time now
Solved! Go to Solution.
03-26-2017 06:09 PM
Hi
You could use an script (or many scripts) and adjust it to your requirements, the following script is just and example:
*If an response is not received from a specific destination, a script will be triggered automatically, removing the primary default route. I usually create an static routing pointing to the primary ISP and to a public IP as my destination for the SLA.
Example: ip route 8.8.8.8 255.255.255.255 1.1.1.1 (primary ISP)
track 10 ip sla 10 reachability
delay down 10
ip sla 10
icmp-echo 8.8.8.8 source-ip 10.0.1.1
timeout 10000
frequency 15
ip sla schedule 10 life forever start-time now
ip sla enable reaction-alerts
03-26-2017 06:09 PM
Hi
You could use an script (or many scripts) and adjust it to your requirements, the following script is just and example:
*If an response is not received from a specific destination, a script will be triggered automatically, removing the primary default route. I usually create an static routing pointing to the primary ISP and to a public IP as my destination for the SLA.
Example: ip route 8.8.8.8 255.255.255.255 1.1.1.1 (primary ISP)
track 10 ip sla 10 reachability
delay down 10
ip sla 10
icmp-echo 8.8.8.8 source-ip 10.0.1.1
timeout 10000
frequency 15
ip sla schedule 10 life forever start-time now
ip sla enable reaction-alerts
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