RE: Problems in Dead Gateway Detection / Failover- MultipleISP Links

Linux Advanced Routing and Traffic Control

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Hi,

I've some similar:

I croned a perl script that every 2 minutes check via ICMP
some referential host ( for each "default route").

If some route is down , I take off it from "default routes table".

But I think that make it by TCP connect at 80 port is better.

bests.

andres



-----Mensaje original-----
De: lartc-bounces@xxxxxxxxxxxxxxx [mailto:lartc-bounces@xxxxxxxxxxxxxxx]En
nombre de Alessandro Ren
Enviado el: Lunes, 17 de Abril de 2006 12:17 p.m.
Para: smundlik@xxxxxxxxxxxxxx
CC: lartc@xxxxxxxxxxxxxxx
Asunto: Re:  Problems in Dead Gateway Detection / Failover-
MultipleISP Links



    I bind to the interface IP and connect to 20 different sites or more,
the sites are listed in a text file, using the TCP connect in perl.
    Off course, the ip rule tables the the marks in the firewall must be set
correcly so you know that the connections are going through the right
interface.
    I can share de script, it's a litle complex in its structus, as it
depends on some external scripts, but I will try the share and problably get
more and better ideas to do the fail over / multi path routing.
    I will prepare and sent a email with it shortly.

    []s.

Shashikant Mundlik wrote:
Hi Ren,

Thanks for your help. But how do you check that you reach less than 20 of
your sites. (do you mean 20 websites?).
Will you able to share the script?
That will be great help.

Thanks and regards,

Shashikant Mundlik

System Administrator
UBICS, Pune
Phone:  91 20 2729 1004  x 138
Mobile : 91 9372 044015

www.ubics.com
The UB Group
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From: Alessandro Ren [mailto:alessandro.ren@xxxxxxxxxxxxxxxxx]
Sent: Monday, April 17, 2006 7:31 PM
To: smundlik@xxxxxxxxxxxxxx
Cc: manish@xxxxxxxxxxxx; lartc@xxxxxxxxxxxxxxx
Subject: Re:  Problems in Dead Gateway Detection / Failover -
MultipleISP Links



    I have a script that connects to 20 diferent sites on the port 80 coming
from each link interface a have on my linux router.
    If I reach less than 20% of my sites, I assume the link is down and do
all the routing and firewall adjustments to make the traffic goes to other
routes, removing the problematic link out, setting ip rules, routes in
tables and the main multipath default route and commenting in the firewall
the MARKs the would go via the link thats down and it also sets QoS and
tries to bring the link that is down back UP.
    Althought I've tested with only 3 links, it supports any number of them.
    It's works very nice so far.

    []s.


Shashikant Mundlik wrote:
Hi There,

I am also trying to do the same for my network.
I have two links from different ISPs and I want to configure a failover and
load balancing Linux router.

I am facing same problem here, that how to detect link failure and let Linux
box switch the gateway.

I know it works when the first gateway is physically down and not reachable.
But what to do if my link is up but there is problem at nexthop level and
its not routing packets to destination.

Please tell me if this can be overcome by setting multipath routing.

Another way I can think of doing this is to use a script which will check if
the default route is alive every 15 mins and if not it will make changes in
routing table and route the packets through different link.

I don't know if this is the best way to do this. If any one know how to do
this better please share.

If you guys thinks this can work, lets help each other to write such scrip.

I am new to LARTC and just now started learning it to solve my network
problems.

Please help me to achieve this.

Thanks in advance.

Regards,

Shashikant Mundlik
Pune, India.

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--
__________________________________________________
Alessandro Ren
OpServices
Luciana de Abreu, 471 - Sala 403
Porto Alegre, RS - CEP 90570-060

(   phone 55(51)3061-3588
4    fax 55(51)3061-3588
Q   mobile 55(51)8151-8212
:   email alessandro.ren@xxxxxxxxxxxxxxxxx

__________________________________________________



--
__________________________________________________
Alessandro Ren
OpServices
Luciana de Abreu, 471 - Sala 403
Porto Alegre, RS - CEP 90570-060

(   phone 55(51)3061-3588
4    fax 55(51)3061-3588
Q   mobile 55(51)8151-8212
:   email alessandro.ren@xxxxxxxxxxxxxxxxx

__________________________________________________

_______________________________________________
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LARTC@xxxxxxxxxxxxxxx
http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc

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