General discussion


Routing multiple networks via single port in cisco

By bhaskar_js ·
hi all

I have a router (1841) with 2FEs

Out of these two ports 1 is connected to my LAN ( with IP

I have two internet links. Each ISP has given me 1 static IP each which I need to configure in my router.

I have configured them, 1 as primary IP and the other as secondary IP in the remaining FE and connected it to a switch and the two internet links also I have connected to the same switch.

Now I need to configure route for Network Subnet in my router so that if 1 link goes down other 1 will automatically start working.

for that I have configured ip route XXX.XXX.XXX.XXX(gateway of first ISP) and ip route YYY.YYY.YYY.YYY(gateway of 2nd ISP)

But my problem is it works only through the primary IP.

Kindly help

Thanks in advance


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Repost as 'Q&A'

by HAL 9000 Moderator In reply to Routing multiple networks ...

Try reposting this in the 'Q&A' forum. The 'Discussion' forum is for matters of general discussion, not specific problems in search of a solution. The 'Water Cooler' is for non-technical discussions. You can submit a question to 'Q&A' here:;content

There are TR members who specifically seek out problems in need of a solution. Although there is some overlap between the forums, you'll find more of those members in 'Q&A' than in 'Discussions' or 'Water Cooler'.

Be sure to use the voting buttons to provide your feedback. Voting a '+' does not necessarily mean that a given response contained the complete solution to your problem, but that it served to guide you toward it. This is intended to serve as an aid to those who may in the future have a problem similar to yours. If they have a ready source of reference available, perhaps won't need to repeat questions previously asked and answered. If a post did contain the solution to your problem, you can also close the question by marking the helpful post as "The Answer".

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SLA feature

by Muhannad.Ali In reply to Routing multiple networks ...

The Cisco SLA feature is your saver
You need to define a SLA prob, which is in your case a PING operation that can keeps working for a pre-defined amount of time or you can configure it to work for good. this operation send a normal PING request to a pre-defined host which is in your case any pingable public IP address to check the connectivity/rechability of that host
The SLA operation must be bound to a TRACK object that report an up/down status according to last return code of the SLA prob... you can use this tracking object in conjunction with one of your default route to acheive an auto failover
So here is what you gonna do
Add a route to the host that you are going to ping for example you want to ping
IP ROUTE "your Primary Gateway"
from the sla sub-configuration mode choose the type of operation icmp-echo
and the host form the source ip address YOUR PRIMARY PUBLIC IP
and then you need to define a TRACK object using the global command
TRACK 1 rtr 1 reachability
the above command will bind the SLA to the track obj. , rtr means sla
then add your track to the default primary gateway
and then add your secondary deafult gateway with an administrative distance higher than the default 1
and that should do the trick
but first make sure your IOS version is capable of configuring the sla operation, if it is not then you need to upgrade your router's IOS to a security or data version because the IP-BASE won't do the trick
if you need more help just let me know...

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