nanog mailing list archives
RE: Default route with object tracking
From: "Brad Tarratt" <btarratt () clearrate com>
Date: Mon, 1 Feb 2010 10:46:05 -0500
Make sure you source your icmp-echos from the address on the interface facing your primary ISP, otherwise your routing table will oscillate continually until your primary ISP comes back up. Here's how I did it with a cable ISP (note my event manager stuff uses no email body to get around the bug in previous versions of IOS, this may no longer be necessary): ip sla 1 icmp-echo <random root dns server> source-interface <internet-facing interface> timeout 3000 frequency 10 ip sla schedule 1 life forever start-time now ip sla 2 icmp-echo <random root dns server> source-interface <internet-facing interface> timeout 3000 frequency 10 ip sla schedule 2 life forever start-time now ip sla 3 icmp-echo <random root dns server> source-interface <internet-facing interface> timeout 3000 frequency 10 ip sla schedule 3 life forever start-time now track 1 rtr 1 reachability delay down 30 up 30 track 2 rtr 2 reachability delay down 30 up 30 track 3 rtr 3 reachability delay down 30 up 30 track 4 list boolean or object 1 object 2 object 3 interface <internet-facing interface> ip dhcp client route track 4 ip address dhcp ip nat outside end ip dhcp-client default-router distance 5 ip route 0.0.0.0 0.0.0.0 somewhereelse 10 event manager applet ISPDown event syslog pattern "%TRACKING-5-STATE: 4 list boolean or Up->Down" action ISPDown.1 mail server "<cellprovidersmx>" to "<mynumber>@<mycellprovider>" from "routers@<mydomain>" subject "ISP Service Down" event manager applet ISPUp event syslog pattern "%TRACKING-5-STATE: 4 list boolean or Down->Up" action ISPUp.1 mail server "<cellprovidersmx>" to "<mynumber>@<mycellprovider>" from "routers@<mydomain>" subject "ISP Service Up" -----Original Message----- From: Andrey Gordon [mailto:andrey.gordon () gmail com] Sent: Monday, February 01, 2010 10:14 AM To: Nanog Subject: Default route with object tracking Hi list. I'd like to setup my default routes to the Interwebz to be conditional on reachability of something on the Interwebz. I got two different ISPs (no BGP). I'm trying to figure out what would be a reliable object to track? Meaning, it's probably not reasonable to track my ISPs default gateway, since it does not protect me from someone on the ISP side screwing up. I'm thinking of tracking something like google.com, but am not sure if after I resolve google.com for the first time, it will be simply tracking an arbitrary server (or some load balancer). I wanted to see what experienced folks think is a reliable tracking target. Any comments are much appreciated. thank you, ----- Andrey Gordon [andrey.gordon () gmail com]
Current thread:
- Default route with object tracking Andrey Gordon (Feb 01)
- Re: Default route with object tracking Dan White (Feb 01)
- Re: Default route with object tracking Curtis Maurand (Feb 01)
- RE: Default route with object tracking Stefan Fouant (Feb 01)
- Re: Default route with object tracking Andrey Gordon (Feb 01)
- Re: Default route with object tracking Christopher Morrow (Feb 01)
- Re: Default route with object tracking Steven Bellovin (Feb 01)
- Re: Default route with object tracking Curtis Maurand (Feb 01)
- Re: Default route with object tracking Scott Morris (Feb 01)
- Re: Default route with object tracking Dan White (Feb 01)