Good Morning People,
I am writing to get some advice and best practices on putting IP SLA's up. Here is my configuration:
I have one 2911 ISR 2 router with two internet lines- One is a cable line (which is connected via ethernet to the providers onsite 1800 router) and the other is a standard ADSL line.
I have a route-map which looks at the source of the traffic (determines whether its staff traffic or server traffic) and splits them accordingly. The Staff go through the ADSL and the servers go through the Cable.
I am trying to get to a position where if one line fails, all traffic goes through the other and vice versa. I have got the route-maps set up to do this using track objects:
route-map r01 permit 20
match ip address SERVERTRAFFIC
set ip next-hop verify-availability x.x.x.x(Cable Gateway) 10 track 1
set ip next-hop verify-availability x.x.x.x(ADSL Gateway) 20 track 2
!
route-map r01 permit 30
match ip address STAFFTRAFFIC
set ip next-hop verify-availability x.x.x.x(ADSL Gateway) 10 track 2
set ip next-hop verify-availability x.x.x.x(Cable Gateway) 20 track 1
This works as I want it to. The problem I am having is the IP SLA's - I have noticed that the IP SLA gets reported down every so often for roughly 5 seconds at a time then comes back up. This is going to cause a big problem when I start setting up the corporate Site-Site VPNS. Here is my config for the IP SLA
ip sla 1 (This tracks the cable connection)
icmp-echo 4.2.2.1
timeout 2500
threshold 2000
frequency 10
ip sla schedule 1 life forever start-time now
ip sla 2 (This tracks the ADSL connection)
icmp-echo 4.2.2.2
timeout 2500
threshold 2000
frequency 10
ip sla schedule 2 life forever start-time now
The way I have currently done it is to ping the DNS servers of a major ISP and force the ping through the appropriate connection by using a static route. So for example, 4.2.2.1 is forced through the Cable connection by a route in my routing table: S 4.2.2.1 [1/0] via x.x.x.x(Cable Gateway)
So, looking at my logs I see the connection dip:
1
4/1/11
9:05:20.000 AM
Apr 1 09:05:20 192.168.50.1 1000: Apr 1 08:05:19.610: %TRACKING-5-STATE: 2 ip sla 2 reachability Down->Up
host=192.168.50.1 Options| sourcetype=udp:514 Options| source=udp:514 Options
2
4/1/11
9:05:10.000 AM
Apr 1 09:05:10 192.168.50.1 999: Apr 1 08:05:09.610: %TRACKING-5-STATE: 2 ip sla 2 reachability Up->Down
host=192.168.50.1 Options| sourcetype=udp:514 Options| source=udp:514 Options
3
4/1/11
8:28:51.000 AM
Apr 1 08:28:51 192.168.50.1 970: Apr 1 07:28:50.426: %TRACKING-5-STATE: 1 ip sla 1 reachability Down->Up
host=192.168.50.1 Options| sourcetype=udp:514 Options| source=udp:514 Options
4
4/1/11
8:28:41.000 AM
Apr 1 08:28:41 192.168.50.1 968: Apr 1 07:28:40.426: %TRACKING-5-STATE: 1 ip sla 1 reachability Up->Down
host=192.168.50.1 Options| sourcetype=udp:514 Options| source=udp:514 Options
5
3/31/11
10:41:10.000 PM
Mar 31 22:41:10 192.168.50.1 943: Mar 31 21:41:10.032: %TRACKING-5-STATE: 1 ip sla 1 reachability Down->Up
host=192.168.50.1 Options| sourcetype=udp:514 Options| source=udp:514 Options
6
3/31/11
10:41:00.000 PM
Mar 31 22:41:00 192.168.50.1 942: Mar 31 21:41:00.032: %TRACKING-5-STATE: 1 ip sla 1 reachability Up->Down
host=192.168.50.1 Options| sourcetype=udp:514 Options| source=udp:514 Options
7
3/31/11
10:12:47.000 PM
Mar 31 22:12:47 192.168.50.1 941: Mar 31 21:12:46.791: %TRACKING-5-STATE: 1 ip sla 1 reachability Down->Up
host=192.168.50.1 Options| sourcetype=udp:514 Options| source=udp:514 Options
8
3/31/11
10:12:42.000 PM
Mar 31 22:12:42 192.168.50.1 940: Mar 31 21:12:41.791: %TRACKING-5-STATE: 1 ip sla 1 reachability Up->Down
host=192.168.50.1 Options| sourcetype=udp:514 Options| source=udp:514 Options
As you can see, this is for 10 seconds and 5 seconds at a time.
Is there a better way of doing what I am wanting to do? I wouldn't have thought it was the DNS servers that are dissapearing for a few seconds now and then but is there a more stable remote host to ping? Any help would be magic as I need to get this problem sorted.
I appreciate any input.
Thank you very much
Tim
