2811 Router - Routing out switch ports

[cwshannon]

I have a 2811 router with a 9 port switch module and a four port ISDN module.  The ISDN Module is our connection to the outside world.  FE 0/0 and FE 0/1 are connected to separate networks and both route our the ISDN connections.

We are getting a new satcom system that consists of a modem, antenna control unit (ACU), and an antenna.  The ACU and the modem communicate accross Ethernet and are generally hooked to a switch.  Anything computer hooked to the switch can simply use the modem IP as it's gateway and be surfing the Internet without much hassle (just need the correct DNS addresses).

I'd like the networks behind FE 0/0 and FE 0/1 to be able to route out the satellite modem for their Internet connection -- when the satellite is available.  Is it possible to put two switch ports in a VLAN (one for the modem and one for the ACU), give the VLAN an IP in the same subnet as the modem and ACU, and then tell the router to route traffic out the modem IP address?

Ultimately I'd like to "failover" to ISDN should we not have a satellite connection, but I wanted to vet my basic concept first before I get ahead of myself.

[meperuma]

Hi,

I am still not clear on your setup, but to me your ISDN and Sat system is a exit point to Internet right? How about floating static route? or ipsla with object tracking

Do you need to change anything on the LAN side when switchover happens? If yes, how about EEM scripting. Monitor the syslog and let EEM to do the config modification.

Just an idea only. moe info will help to understand ur req.

Sent from Cisco Technical Support iPhone App

[sujinair]

Hi Chris,

In your setup, you may put two switch ports in the same vlan and connect your Modem and ACU to that. Next step would be to create a VLAN interface as you have mentioned and put that in the same subnet as that of your modem. To route the internet traffic out of the modem all you need is to configure a default route pointing towards the modem IP and configure NAT accordingly (if required).

To configure a failover scenario you may use floating static routes and IP SLA tracking. Also you will have to make some modifications in your NAT statements. You may check the following links for more info:

Reliable Static Routing Backup Using Object Tracking

http://www.cisco.com/en/US/docs/ios/dial/configuration/guide/dia_rel_stc_rtg_bckup_ps10591_TSD_Products_Configuration_Guide_Chapter.html

IOS NAT Load-Balancing for Two ISP Connections

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_configuration_example09186a0080950834.shtml

Regards,

Sujit

[cwshannon]

Thanks for the help.

I'll research the guides you've linked.  This sounds like exactly what I need.

Chris

[sujinair]

Great! lemme know if you have any further queries. You may also check my article on IP SLA, it has a small config example.

http://www.firewall.cx/tk-cisco-ipsla.php

Cheers!

Sujit