Solved

Failover for internet line through DNS

Posted on 2004-10-18
4
235 Views
Last Modified: 2013-12-14
Hi all,

let me first explain what we are trying to do:

We have one apache server and two netgear routers. Each router has it's own static external IP adress. Each router uses a different internet line (aka ISP) so if one ISP goes down, the other one should still operate (of course this depends on which backbones the ISPs are actually using, but let's assume that one line can be up while the other one being down).

The server should be available under the DNS entry server.mycompany.com. It is typically reached through router 1 / internet line 1. But when line 1 goes down, server.mycompany.com should be reached via router 2 / internet line 2.

example:
- router 1 is using a fast line and has IP address 100.1.1.1
- router 2 is using a slow (backup) line and has IP address 200.2.2.2
- DNS entry server.mycompany.com is pointing to 100.1.1.1

now, when the fast line is down, I want server.mycompany.com to be quickly updated to 200.2.2.2.

when talking to my ISP I was told that DNS updates from their side can take some time to propagate.

My questions are as follows
- how comes that services like dyndns.org see to propagate the updates within seconds ?
- can anybody think of another alternative to setup failover for internet lines ?

Thanks
Holsche

PS: just for the records - yes we have a backup server as cold stand-by :-)
0
Comment
Question by:Holsche
  • 2
  • 2
4 Comments
 
LVL 5

Expert Comment

by:AutoSponge
Comment Utility
Have both of your ISPs propigate the routes to the other ISP's network space that you lease.

ISP 1 - you lease 100.1.1.1 and 100.1.1.2 (your server)
ISP 2 - you lease 200..2.2.2 and 200.2.2.3 (your server second NIC)

Turn on bridging so the Apache will forward packets coming in on ISP 2 destined for 100.1.1.2 to the other interface instead of dropping them and visa versa.

Have each ISP add the following information to their routers.
ISP 1 - Static route to 200.2.2.3 next hop 100.1.1.2
ISP 2 - Static route to 100.1.1.2 next hop 200.2.2.3

0
 

Author Comment

by:Holsche
Comment Utility
AutoSponge - thanks for your suggestion, but - honestly, I don't understand how this suggestion works.
0
 
LVL 5

Accepted Solution

by:
AutoSponge earned 200 total points
Comment Utility
Well, each ISP's router needs to know about the other network address your server has.  This should then be re-distributed in BGP by those routers into the ISP's AS.  Now each ISP has a route to each NIC on your server.  Because of the way BGP works, people will be directed to the shortest path for them to your server (depending on which ISP's AS is closer).  Then, if one AS is unreachable or your router's connection to the network drops, the other link will continue to route to both addresses beacuse, while it may be a longer path, at least it will complete.

Just make sure that both ISPs are advertising both of your IP addresses and that your router or server will forward the traffic accordingly.  If you don't have a router of your own, you're going to have to test the bridging capabilities to make sure this works.  Best bet is to have a router in front of the server that is connected to both ISP routers and has two Eth ports that plug into the two NICs on the Apache.
0
 

Author Comment

by:Holsche
Comment Utility
thanks !!! now it's clear :-)
0

Featured Post

Maximize Your Threat Intelligence Reporting

Reporting is one of the most important and least talked about aspects of a world-class threat intelligence program. Here’s how to do it right.

Join & Write a Comment

Suggested Solutions

    Over the past few years, small business and home owners have become so dependent on internet that a need for redundancy has arisen.    What happens when your small business or home / home office loses its internet connection?  The results c…
Sometimes you have to pull out old tricks to get a new firewall to work… While we were installing a new Sonicwall at a customers site we found that sites they were able to visit before were not working.  It seemed random and we could not understa…
Sending a Secure fax is easy with eFax Corporate (http://www.enterprise.efax.com). First, Just open a new email message.  In the To field, type your recipient's fax number @efaxsend.com. You can even send a secure international fax — just include t…
You have products, that come in variants and want to set different prices for them? Watch this micro tutorial that describes how to configure prices for Magento super attributes. Assigning simple products to configurable: We assigned simple products…

744 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

Need Help in Real-Time?

Connect with top rated Experts

11 Experts available now in Live!

Get 1:1 Help Now