How to configure Async as a backup for E1

[mmozanen]

Dear all,

I've been assigned a task to install a new E1 line between remote and central site.

We have a running Async connectino which connect the remote site using 1720 router and USRobotics modems. It's working fine (with some miss-understood configuration done by a previous system eng.).

Any way I'm about to install a new E1 interface in both site and connect both sites.

What I want to do, Is to make the E1 the primary connection. And use the Dial line, as a backup.

What do yo suggest. About routing and line configuration.

Is it better to make it dynamic, or static ??

And what is the best for my situation.

With regards

[makchitale]

If I understand you have a new E1 lease line that you want to backup with the existing analog lines, which means we already have the analog part working but just want to utilize when the backup functionality is required.

The below configuration should help (note instead of LL we have a frame ckt):

http://www.cisco.com/en/US/tech/tk801/tk36/technologies_configuration_example09186a0080094555.shtml

The below link has lots of good info on which backup scheme to use floating static or backup command or dialer watch:

http://www.cisco.com/pcgi-bin/Support/browse/psp_view.pl?p=Technologies:DDR&s=Implementation_and_Configuration

Thanks, Mak

[spremkumar]

Hi

few questions before getting into implementation..

1.r u connecting both E1 and async on the same router ??

if yes then better run static routes instead of dynamic but do clear whether u r running any dynamic protocol in central site ?

2.Speed - theres a big lot of diff between E1 and Async connecitivity u wont get whtever the perf u were getting in E1 once u connect with aysnc.

Better would suggest to go for an isdn backup in future instead of async.

do chek this link ..

http://www.cisco.com/en/US/tech/tk801/tk379/technologies_configuration_example09186a0080093fc4.shtml

regs

prem

[vcjones]

Assuming you have a working async link today which recovers well from hangups and other link failures...

You _could_ simply set up the leased line and add the statement "backup interface " to the leased line interface configuration.

But you really should develop an understanding of your requirements, the range of dial backup options available, and the limitations of your selected solution first. There are some significant trade offs required, from the downtime allowable before backup is available and acceptable levels of performance while on backup to the probability that whatever takes down your primary link will also take down your backup link.

When making the choice, keep in mind not just today's applications, but also those that will be added to take advantage of the T1 bandwidth becoming available. Also take into account not only the cost of downtime, but also the cost of maintaining and testing the backup configuration to ensure that by the time it is needed, it is still working.

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com