[LARTC] Problem with Load Balancing

Vladimir Burciaga Aguilar anakinv7 at hotmail.com
Mon Sep 18 18:09:29 CEST 2006


>We have also set up a somewhat similar method of load balancing.  Our
>traffic is never a 50-50 split (well 3:2 is how we have it set, but it
>doesn't always get close to that), but as the load picks up, it tends to be
>closer to the actual amount.

Well, then there is not much to do about this.

>Dead gateway detection has never worked for us, and one day I'll probably
>bother other members of the LARTC group to get some help, but the method
>that we use is to check the output of the ip neighbor command.  Basically,
>if our two ISPs are 10.1.1.254 and 10.2.2.254, we run a bash script via 
>cron
>every minute that does a call something like:
>
>ETH1 = ip neigh 10.1.1.254 | egrep "REACHABLE|DELAY|PROBE|STALE" -c
>ETH2 = ip neigh 10.2.2.254 | egrep "REACHABLE|DELAY|PROBE|STALE" -c
>
>The neighbor system basically monitors ARP and if it sees a message leave 
>an
>interface without a reply after something like 3-5 seconds, it moves the
>interface to DELAY, after another few seconds it moves to PROBE and does an
>active arp request, and if that fails to work in a few seconds, it becomes
>INCOMPLETE or FAILED or just simply isn't listed.  If no data is sent 
>either
>way for a while, the entry can be marked STALE or removed.
>
>With the above lines, we get a 1 in the ETH1 or ETH2 variables if the next
>neighbor is up, and a 0 if not.  From there you can use some if scripts to
>detect if both are up, or if only one is up, which one.  In our case, if
>both are up we clear the default route and then make it something like
>
>ip route add default nexthop via 10.1.1.254 dev eth1 weight 1 \
>nexthop via 10.2.2.254 dev eth2 weight 1
>
>and if only one is up we clear it and make it :
>
>ip route add default nexthop via 10.1.1.254 dev eth1
>or
>ip route add default nexthop via 10.2.2.254 dev eth2


Ok, William, this looks like what I'm looking for. I'm going to test it and 
tell you how it works for us. By the way, about the download of a single 
file between the two conections, do you know if there is a way to do it?

Thanks for your help and time and sorry for the delay!

_________________________________________________________________
Prodigy/MSN Spaces: Tu espacio en la red http://spaces.msn.com/



More information about the LARTC mailing list