Re: Internet connection redundancy (DSL and 4GLTE)

[Niels Dettenbach <nd%syndicat.com@localhost>]

Am Mittwoch, 8. Juni 2022, 09:38:30 CEST schrieb BERTRAND Joël:
>         Now, I'm trying to automatically change default route (from
> 192.168.15.20 to 192.168.15.19 and reciprocally) when DSL connection is
> down.
there are lot of different ways to implement such a "automatic failover" with 
different pros and cons.

The "simplest" but hacky way may be to use ppps ip-up/down / pre-up/down or 
similiar parameters / scripts with simple shell scripts to switch forth/back 
the default route when the ppp interface goes down or up. To get this work 
well, ppp has to be cofigured to check the link "health".

NetBSD allows many standard routing protocols which - in parts - may provide 
similiar solutions.

One problem is, that all these solutions does not recognize if your ISP has 
some "uplink" down, because it only checks the health of the DSL connection. 
In such cases your failover would not switch as you might want that. Some ppl 
write scripts which ping some "highly available" IP somewhere in the internet 
to check if "internet connectivity" really works and let switch over by shell 
if a ping series goes to nirvana.


hth,
cheers,


niels.


-- 
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 Niels Dettenbach
 Syndicat IT & Internet
 https://www.syndicat.com
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