Redundant or Backup ISP Links

Pravin Phadte · ‎11-04-2008

there a doc in cisco which speaks of configuration of backup links.

question;

sla monitor 123

type echo protocol ipIcmpEcho "IP address" interface outside

num-packets 3

frequency 10

The ip address can be any ipaddres on the internet ?

What happens if i specify the ip address like 4.2.2.2 ?

if the ping responce stops to this ip will it switch to the backup link ?

Do i need to specify only the next hop ?

husycisco · ‎11-04-2008

Hello Pravin,

"if the ping responce stops to this ip will it switch to the backup link ?"

Thats correct

"The ip address can be any ipaddres on the internet ?"

Yes it can. But since the purpose of this sla monitor is tracking the connectivity of your ISP connection, the best practise is tracking the gateway of your connection, which is your ISP, the next hop. Your gateway down means your ISP is down for you, but we can not say the same thing for any host on internet. A failure in 4.2.2.2 itself or on its path will cause an sla loop between your sla monitors.

Regards

Pravin Phadte · ‎11-04-2008

I will be checking this and let u knw.

so if i keep a sla to the ip for 4.2.2.2 and then disconnect the primary line. Will it switch to backup ?