02-23-2006 10:45 AM - edited 03-03-2019 01:59 AM
I have a Cisco 1721 router. The S0 int. connects to my intranet 192.168.104.1
The Fa0 int, connects to the internet. Is it possible to get the router to detect if the internet goes down to redirect the traffic back out the S0 port to another router in the network that has a separate internet connection?
Any suggestions and configs would be greatly appreciated.
Thanks
Dale
02-23-2006 01:01 PM
You mean when the interface goes down, right? Or the device connecting to the fa0 goes down? You can do floating static route pointing the serial interface with a slighty higher distance metric than the route to fa0 if and when the interface fa0/1 ever goes down.
something like:
ip route 0.0.0.0 0.0.0.0 interface serial
02-23-2006 03:55 PM
Thanks, I will try this and let you know
02-24-2006 12:19 PM
Ok that didn't work for some reason. I put in the route
ip route 0.0.0.0 0.0.0.0 interface serial0 254
and when I shut down the fa0 interface I never regained internet activety.
I can ping the router I need to get to from this router, but when the interface went down nothing happened.
The router I'm on has the following int configs
fa0 69.146.108.59 255.255.255.248
S0 192.168.104.1 255.255.255.0
the router that points at this
S0 192.168.104.2 255.255.255.0
fa0 10.6.18.8 255.255.255.0
The other internet router is
fa0 10.6.18.4
How do I get the first router to get to this router should the first routers internat connection go down?
Thanks Dale
ip route 0.0.0.0 0.0.0.0 69.146.108.57
The router I'm trying to get to
02-23-2006 01:04 PM
Hi Dale,
To make that work, you will need to use the reliable static route backup feature...
Try something like this...
Replace
interface FastEthernet 0
description Primary Link
ip address 10.1.1.1 255.0.0.0
!
interface Serial0:1
ip address 192.168.104.1 255.0.0.0
!
rtr 1
type echo protocol ipIcmpEcho
timeout 1000
frequency 3
threshold 2
!
rtr schedule 1 life forever start-time now
!
track 100 rtr 1 reachability
!
access list 101 permit icmp any host
!
route map LOCAL_POLICY permit 10
set ip next-hop 10.1.1.254 ! set this to the ISP side address of your WAN link
set interface null0
!
ip local policy route-map LOCAL_POLICY
!
ip route 0.0.0.0 0.0.0.0 10.1.1.254 track 100
ip route 0.0.0.0 0.0.0.0 Serial0 254
Hope that helps - pls rate the post if it does.
Paresh
02-23-2006 03:56 PM
Thanks, I won't get to run this until tomorrow. But if it works I will rate your post asap.
02-24-2006 11:03 AM
Paresh,
Apparently my router isn't capable of this. It's a 1721 running version 12.3<6>.
I'm not able to do anything with the rtr 1,,type echo... etc.
any other ideas for a simpler IOS
Thanks
Dale
02-24-2006 01:31 PM
So your fast-E interface is on the outside and your Serial is on the inside? Hmmm...perhaps turning on keepalives and simple interface line protocol tracking might work; something like:
interface fa0
keepalive
!
track 1 int fa0 line-protocol
...then run HSRP between your two routers' inside interfaces; I've never done it across serial interfaces, but as long as they are layer-2 adjacent, I would think it would work; something like:
interface s0
ip address
standby 1
standby 1 priority 105
standby 1 track 1 decrement 10
...the other router would look similar, except for the real IP of course. You can choose to track its outside interface or not. Better yet, if both links are available, asymmetric routing is of no concern and there are many inside hosts going out to the Internet, look into GLBP instead of HSRP.
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