Ip Sla Configuration For Failover

Icmp-echo source-ip Ip sla schedule 1 life forever start-time now! Icmp-echo source-ip Ip sla schedule 2 life forever start-time now! Track 1 ip sla 1 reachability! Track 2 ip sla 2 reachability! IP SLA setup for WAN links failover. Configure IP SLA to test the Primary connection by pinging a remote IP that should normally be reachable, e.g. Google's public DNS server at or the ISP's gateway address (in this example If you are using a remote address other than the ISP's gateway, ensure you also add a static route to the remote IP via the gateway.


Cisco Load Balancing with Failover setup example


ASA(config)# sla monitor 10 Configure the SLA monitor with ID 10 ASA(config-sla-monitor)# type echo protocol ipIcmpEcho interface outside Configure the monitoring protocol, the target IP for the probe and the interface use SLA monitor will keep probing the IP we define here and report if its unreachable via the given interface.

There is Cisco router of 7200 series with four FastEthernet interfaces (FE) and a pair of serial ports. It ought to act as load balancer and failover for square measurea network LAN computer network} connected thereto via one atomic number 26 1/0 interface whereas 2 identical web connections are reaching to atomic number 26 0/0 and atomic number 26 0/1 (let’s name these connections as ISP_1 and ISP_2).
No dynamic routing protocols square measure utilized by ISPs however solely static routing. the first task is to make sure fast failover between 2 web connections thus square measurea network LAN computer network} users are mechanically switched to ISP_2 if ISP_1 fails and the other way around. once each ISP_1 and ISP_2 square measure on-line the traffic of computer network users ought to be shared between 2 links to double offered information measure on transmission (Tx) and downlink (Rx), in different words the router ought to be organized for load equalization between the links.

Load equalization setup description


There are 2 basic choices available: per-destination or per-packet load equalization. Since ISP_1 and ISP_2 connections have virtually constant link characteristics as well as delay, interference and information measure, it’s affordable plan to select per-packet possibility. compared to per-destination load equalization approach per-packet uses additional router’s hardware resources however makes it attainable to share traffic between connections additional equally. For higher forwarding performance the router are organized for Cisco specific Forwarding or just CEF per-packet load equalization.

Ip Configuration Failure

Failover description
Every thirty seconds the router can ping 2 informatics addresses through ISP_1 and 2 alternative informatics addresses via ISP_2. If each IPs via ISP_1 becomes unapproachable (we assume that ISP_1 association fails during this case) the router can delete ISP_1’s route from its routing table therefore ISP_2 becomes the sole net association for computer network users. in the meantime the router still continues pinging 2 ISP_1’s informatics addresses and once they become accessible back ISP_1 is more to ISP_2 as a vigorous net association link. Such failover situation works in completely constant manner for ISP_2. typically this can be affordable plan to ping informatics addresses of every provider’s DNS servers once watching convenience of every ISP.

Miscellaneous details
Notice that CEF per-packet load balancing requires IOS version of 12.0+ while failover setup described above needs 12.4+ IOS version so you have to make sure your Cisco router runs at least 12.4 version of operating system. E.g. c7200-ik9o3s-mz.124-12c.bin would be ok.

Cisco Router Failover Configuration

Cisco router’s configuration with comments