back up link for fast ethernet

[waqasashraf1]

hi,

the scenario is like this that i have 2 1841s one at the branch end an the other at the central office, both the routers are connected through DSL modem on fast ethernet ports, the problem is that i want to setup a redundant link for backup puropse using the bri 1/0 on the both the routers, i am not even running ppp on the fastethernet. thw questiion is how will the router tell the bri to initiate an isdn call in case of the failure of the fast ethernet link? Please reply with configurations if possible.

[lgijssel]

This issue calls for the use of floating static routes. Please check the URL below for an example:

http://www.cisco.com/en/US/tech/tk801/tk133/technologies_configuration_example09186a0080093d6e.shtml

Regards,

Leo

[waqasashraf1]

Thanks Leo, but i have already gone through this example on the weekend but if you obsereve,the primary link is on the serial interface, in which this simple solution would do butthe problem with my scenario is that the routers are connected through cable dsl on the fastethernet port, and when the fastethernet port goes down it doesnt show that it has gone down.

[lgijssel]

That makes little difference for it's operation.

Essetially the backup kicks in when the routing protocol loses the primary route.

So the basics are:

1: establish a routing protocol over the primary link.

2: configure static routes over the backup path with a higher distance than the primary routes.

This solution will work when an interface goes down but also when there is a disruption in connectivity.

Regards,

Leo

[waqasashraf1]

thanks, will i also need to configure ddr to activate the bri, or will it place the call to the remote site itself. what i think is ddr neccessary? can you comment on this?

[attrgautam]

You can also look at route tracking using object tracking. Yes you will need a ddr to trigger the bri.

[waqasashraf1]

can you provide me some sample configuration for enhanced object tracking, though i am working on it but it would help, also is DDR required for the floating static routes?

[attrgautam]

http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123newft/123limit/123x/123xe/dbackupx.htm

This should help. You need DDR with floating static routes. Let me know if it helps

[lgijssel]

You definitely need to set up DDR. Look at it as two different ways to connect sites. If the ethernet link fails, DDR takes over.

Regards,

Leo

[waqasashraf1]

thanks i did get that in the first instance but i ijust wanted to be sure before applying this in the real time scenario

[emadehsan]

Hello

I think of the best ways to determine the failure of etherlink is using SLA or SAA/RTR

if you need more information let me know

regards

[waqas.ashraf]

yeah if you can elaborate this with some examples and configurations, i will be thankful