Solved

ISDN backup for xDSL line

Posted on 2004-10-20
6
240 Views
Last Modified: 2013-12-14
Currently I have a primary 1M primary DSL link going to internet. I'm using DSL modem and a Cisco 1721 router as my gateway. I have BRI S/T interface and need to use my ISDN line as a backup link.

How do i make my ethernet interface go down when my sdsl link goes down? At the moment at my router i have put 'backup interface dialer 1' on my ethernet interface, however the ethernet wont go down when the sdsl line goes down.

Another method i tried was setting the default route going to internet with the ISDN link having an AD of 2 as shown below;-

ip route 0.0.0.0 0.0.0.0 BVI1
ip route 0.0.0.0 0.0.0.0 Dialer1 2

When i disconnected the line, the router wont go through the ISDN even after sometimes. If  I remove the line 'ip route 0.0.0.0 0.0.0.0 BVI1' then the router goes through the ISDN link. Any way for me to make this automated.


0
Comment
Question by:ason
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
6 Comments
 
LVL 43

Accepted Solution

by:
JFrederick29 earned 500 total points
ID: 12368667
This Cisco document explains exactly what you need to do when dealing with an ethernet based connection to your ISP.  The second route is never used because as far as the router is concerned, the ethernet interface connected to the DSL modem is still up/up.  The router will never know a failure exists upstream.  This article explains how to send an ICMP packet to verify the next-hop-address is reachable before using the route.  If the DSL line is down, the router will attempt to ping the next hop via the DSL line, since the line is down, the next hop is unreachable.  The backup line will be verified and if the next hop is reachable, it will be used.

http://www.cisco.com/en/US/tech/tk364/tk871/technologies_configuration_example09186a0080211f5c.shtml
0
 
LVL 5

Expert Comment

by:AutoSponge
ID: 12380778
0
 

Author Comment

by:ason
ID: 12407455
Sorry forgot to mention earlier, apparently the SDSL modem used is capable of routing and it is the router next hop before going to the ISP network. So basically the route will never get removed since the link between the router and the modem never goes down. So unless i unplug the ethernet cable between router and modem, the router primary route will still point to the modem.

The modem is provide by the broadband provider, so i have no control over it. Any other method apart from backup interface, floating static routes and dialer watch?

0
 
LVL 43

Expert Comment

by:JFrederick29
ID: 12409600
Did you read my post?

Give the link a read, it is exactly what you need to do...
0

Featured Post

What is SQL Server and how does it work?

The purpose of this paper is to provide you background on SQL Server. It’s your self-study guide for learning fundamentals. It includes both the history of SQL and its technical basics. Concepts and definitions will form the solid foundation of your future DBA expertise.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This solves the problem of diagnosing why an internet connection is no longer working. It also helps identify the likely cause of the lost connection if the procedure fails to re-establish your internet connection. It helps to pinpoint the likely co…
Cable Modem Provisioning from DPoE compliant server  This Article is to support CMTS administrators to provide an overview of DOCSIS compliance configuration file, and to provision a cable modem located at customer place from a Back office serve…
There's a multitude of different network monitoring solutions out there, and you're probably wondering what makes NetCrunch so special. It's completely agentless, but does let you create an agent, if you desire. It offers powerful scalability …
In this video we outline the Physical Segments view of NetCrunch network monitor. By following this brief how-to video, you will be able to learn how NetCrunch visualizes your network, how granular is the information collected, as well as where to f…

705 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question