[wplug] Dual Ethernet Ports - One routing table

Andrew Fisk andy at spitcomp.com
Tue Aug 25 14:15:25 EDT 2009


how about a cron job that fires off a ping every couple of minutes,  
while not elegant, it's simple and will keep the network connection  
alive.




Andy
Spitfire Computer Services
Suite 19
2301 Duss Ave.
Ambridge, PA 15003
Phone (412) 749-0162
andy at spitcomp.com
www.spitcomp.com






On Aug 25, 2009, at Tuesday, August 25, 20092:03 PM, Weber, Lawrence A  
wrote:

> I have the need to interface a Linux system to two separate  
> subnets.  I have run into a problem when one of the ports goes down  
> due to either being disconnected for a minute or due to no network  
> traffic for approximately 3 minutes.  When the port goes down it  
> routes the down-port's output to localhost.  When a valid message is  
> then received from a gateway, the system looks into the routing  
> table and gets confused because it finds two default gateways (one  
> for each subnet).  The confusion occurs even though the default  
> gateways are assigned to individual interfaces (eth0 - eth1).  If it  
> picks the wrong default gateway, it cannot reach the gateway, so it  
> assumes that the network is still down and sends the response to  
> itself.  There must be a timer involved here too because after 4 to  
> 5 minutes the interface re-establishes itself and works fine.  As  
> long as there is regular traffic through the gateway the interface  
> never goes down.
>
> I have heard that there can be multiple routing tables, one for each  
> port and that a priority routing database is used to assign tables  
> to ports.  Has anyone had to implement multiple routing tables?   
> Does the database need to know the subnet address for every message  
> received through its gateway?
>
> I really want to keep the configuration of this system as simple as  
> possible, as people who know less about networking than I do (if  
> that is possible) will have to set up the port parameters.  Ports  
> will have fixed address, no DHCP.
>
>
> L. A. Weber
> _______________________________________________
> wplug mailing list
> wplug at wplug.org
> http://www.wplug.org/mailman/listinfo/wplug

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