LARTC - Feb 2005 - Redundant Links Routing

I have two LANS connected by two different pipes:

            -------------                -------------
   LAN 1 --|--eth0  eth1-|-- VPN link --|-eth1  eth0--|-- LAN 2
           |             |              |             |
           |             |              |             |
           |             |              |             |
           |        eth2-|-- T1  Link --|-eth2        |
            -------------                -------------

VPN - Link over the Internet 3mb Fiber
T1 - Fractional - equaling 256k bandwidth
                       
I am looking to have a dominant route between LANS over the VPN link. The T1
Link is a backup. My questions are the following: 

If I do a split access between the VPN and T1 links giving weight of a 1 to
the VPN and a weight of 2 to the T1 link and I should loose either
connection am I correct to say that I will still suffer loss of connections.
I am assuming that the weighting option being round robin is not ideal for
redundant setups. Is it primarily for load balancing? Am I wrong here?

Second question, would it be a better solution to tie the links together for
load sharing as chapter 10 states in the Adv-Routing-HOWTO? 

My problem is not load, but routing for unlike redundant lines. I could care
less if anything goes across the T1 link unless the VPN link goes down. The
idea is to have the Linux boxes eliminate manual re-routing in the event of
a link failure. Maybe I have missed the ideal setup altogether.

Any point in the right direction would be a great help.

Thanks much in advance,
Doug  
_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/

Maybe a better way of asking this question is if I use link load balancing
and one of the links fail would the remaining link continue to function
normally without interruption to service. The second question is concerning
the differences in link speeds will it degrade performance in comparison to
only using the high speed link? Looking through the HOWTO and searching the
archives I have not found the "what if" answers.

Thanks in advance,
Doug

-----Original Message-----
From: Doug Johnson [mailto:doug.johnson@vifanusa.com]
Sent: Thursday, February 10, 2005 5:29 PM
To: ''lartc@mailman.ds9a.nl''
Subject: [LARTC] Redundant Links Routing


I have two LANS connected by two different pipes:

            -------------                -------------
   LAN 1 --|--eth0  eth1-|-- VPN link --|-eth1  eth0--|-- LAN 2
           |             |              |             |
           |             |              |             |
           |             |              |             |
           |        eth2-|-- T1  Link --|-eth2        |
            -------------                -------------

VPN - Link over the Internet 3mb Fiber
T1 - Fractional - equaling 256k bandwidth
                       
I am looking to have a dominant route between LANS over the VPN link. The T1
Link is a backup. My questions are the following: 

If I do a split access between the VPN and T1 links giving weight of a 1 to
the VPN and a weight of 2 to the T1 link and I should loose either
connection am I correct to say that I will still suffer loss of connections.
I am assuming that the weighting option being round robin is not ideal for
redundant setups. Is it primarily for load balancing? Am I wrong here?

Second question, would it be a better solution to tie the links together for
load sharing as chapter 10 states in the Adv-Routing-HOWTO? 

My problem is not load, but routing for unlike redundant lines. I could care
less if anything goes across the T1 link unless the VPN link goes down. The
idea is to have the Linux boxes eliminate manual re-routing in the event of
a link failure. Maybe I have missed the ideal setup altogether.

Any point in the right direction would be a great help.

Thanks much in advance,
Doug  
_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/