[c-nsp] Dual WAN on Cisco IOS 12.4(24)T

Luan Nguyen luan at netcraftsmen.net
Wed Apr 15 11:56:58 EDT 2009


Basically you should look for reliable static routing using object tracking
http://www.cisco.com/en/US/docs/ios/12_3/12_3x/12_3xe/feature/guide/dbackupx
.html

An ICMP echo probe is created to monitor the GW of the primary interface.
The probe sends an ICMP echo every 5 seconds, and runs indefinitely:

ip sla 2147483647
 icmp-echo x.x.x.x(GW) source-ip x.x.x.x1 [PRIMARY ADDRESS]
 timeout 1000
 frequency 5
ip sla schedule 2147483647 life forever start-time now

An object tracking rule is created to track the echo probe with a delay of
20 seconds - in case of just link flapping and not a real failure:
!
track 300 rtr 2147483647 reachability
 delay down 20
!
A route map is created to send the ICMP echo packets out the primary WAN
interface only when it is up but sends the packets to a null0 interface when
the primary interface fails.
!
ip access-list extended object-track
 permit icmp host x.x.x.x1 host x.x.x.x
!
route-map OT permit 300
 match ip address object-track
 set ip next-hop x.x.x.x
 set interface Null0
!
A default route is set out the primary interface. Another default route is
set out the secondary interface but at a higher cost.

ip route 0.0.0.0 0.0.0.0 x.x.x.x track 300
ip route 0.0.0.0 0.0.0.0 y.y.y.y 250
!

HTH.

Regards,

----------------------------------------------------------------------------
---------
Luan Nguyen
Chesapeake NetCraftsmen, LLC.
[Web] http://www.netcraftsmen.net
------------------------------------------------------------------------


-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of John Lange
Sent: Wednesday, April 15, 2009 11:02 AM
To: 'Cisco NSP'
Subject: Re: [c-nsp] Dual WAN on Cisco IOS 12.4(24)T

On Wed, 2009-04-15 at 10:24 -0400, Luan Nguyen wrote:
> You could put Fa0 into a VLAN and use that for the cable modem
> connection.

Ok, that's what I figured would work.

Any suggestions for how to make the dual-wan work in a type of fail-over
setup? All of my searching turns up plenty of hits for hardware failover
(dual-PIX setups) but I can't find any example configs for dual-wan on a
single device. I must be using the wrong search terms?

I'm fairly new to cisco and am not certified so any hints as to which
IOS commands/configs can be used to detect fail-over would be great.

Thanks,
-- 
John Lange
http://www.johnlange.ca

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