PBR with SLA track

jmprats · ‎05-04-2010

Hi, I have 2 ISPs and I would like to navigate through one of them (ISP1) until the performance of the line is falling down (for example, I can test an Internet DNS server for icmp-echo > 200 ms), then I have to route to ISP2 until the perfomance on ISP1 is back

I have done this configuration:

ip sla 1

icmp-echo ip_internet

timeout 200

frecuency 30

ip sla schedule 1 start-time now life forever

track 1 rtr 1 reachability

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 Dialer1 10

My problem is that when track fails the router changes the route to ISP2, but in this moment the icmp-echo to an internet server its ok again through the new ISP2, so it changes the route again to ISP1, then track fails and changes to ISP 2, and so on.

How can I avoid that? I would like to track the Internet Server always through ISP1, not through the default route in that moment. Is this possible?

Is there a solution

Thanks

Giuseppe Larosa · ‎05-04-2010

Hello Jmprats,

I would consider to track IP reachability of an ISP1 public address, rather then checking a public DNS server somewhere in the Internet

The way you have built the test causes this bouncing effect

Hope to help

Giuseppe

jmprats · ‎05-04-2010

Yes, but ISP1 public Ip addressess are available from ISP2 too

, so when I'm tracking them from ISP2 I will have the same effect (a continous change of the default route)

Thanks

paul.basford · ‎05-04-2010

Also, I would add a static route to the IP address you are monitoring with the SLA to make sure it always goes

via ISP1. e.g -

ip route ip_internet 255.255.255.255 1.1.1.1 (i'm assuming this is ISP1 from your config)

jmprats · ‎05-04-2010

Very good idea. Thanks, I will try