From mboxrd@z Thu Jan 1 00:00:00 1970 From: Manish Kathuria Date: Fri, 21 Apr 2006 01:49:52 +0000 Subject: Re: [LARTC] Problems in Dead Gateway Detection / Failover - Multiple Message-Id: <44483A0A.50107@tuxspace.com> List-Id: References: <43D8CEAE.3010006@tuxspace.com> In-Reply-To: <43D8CEAE.3010006@tuxspace.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: lartc@vger.kernel.org Eduardo Fern=E1ndez wrote: > Hi! >=20 > Did you finally write a script for dead gateway detection beyond first > hop? Did you find any other solution to this problem? I'm quite > interested and I bet other multipath users here are interested too. >=20 > My linux router has 10 dsl links (adding 15 more in short), when one > of the dsl routers goes down the kernel does not always notice. Don't > know why. Also, if a dsl route is up but the internet link is down > dead gateway detection doesn't work either. >=20 > Thanks! >=20 > Edu >=20 >=20 If you follow the nano.txt procedure and apply the patches, it works=20 perfectly as long as the first hop is dead. But to ensure failover, when=20 connectivity goes down at any of the hops, you can use the nano.txt=20 for configuring the interfaces and multipath routes (call it default=20 configuration) and also run a script in the background to modify the=20 routes as described below. 1. Periodically keep on checking if a remote host is reachable from each=20 of the gateways by pinging it after every n seconds. 2. If the remote host is not reachable after a number of tries (which=20 you can decide according to your own specific situation) from a=20 particular gateway, remove that route. If you have just two internet=20 links, there would be only one gateway left. But if you have more than=20 two links alive you can again define multipath routes with appropriate=20 weights for the active gateways. The possible combinations will increase=20 exponentially with the increase in number of internet links so you will=20 have to factor is all the cases in the script. 3. Restore the default configuration when the remote host is reachable=20 from all the gateways. I am not too sure how its going to behave with 10 links because if the=20 links are not so stable it will result in very frequent changes. -- Manish Kathuria http://www.tuxspace.com / _______________________________________________ LARTC mailing list LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc