Implementing SLA

Hi All,

I have a lab I’m trying to work out where there is a router connected to an ISP with 2 links (10.20.30.0/24 10.20.40.0/24) over serial connection. The ISP has 3 loopbacks, 1 which is simulating a webserver, the other 2 simulating DNS servers. What the question is:

SLA probes should be implemented to monitor DNS servers (simulated by loopbacks on the ISP router, with addresses 200.100.0.1/24 and 200.200.0.1/24) to maintain connectivity to a web server (simulated by a loopback with address 200.150.0.1/24).

I assume that is a DNS server goes down then it will change from 10.20.30.0 to 10.20.40.0 but how do I monitor 1 loopback and change the link of the ISP?

Hi Jerry,

Did you see this example?

https://networklessons.com/ip-routing/reliable-static-routing-with-ip-sla/

I guess that’s pretty much what you are looking for. You can track an IP address and when it doesn’t respond, the route gets removed. You can modify it so it uses DNS queries/replies.

Rene