From: "Gáspár Lajos" <swifty@freemail.hu>
To: "Usuário do Sistema" <maiconlp@ig.com.br>
Cc: Lloyd Standish <lloyd@crnatural.net>,
Andrew Beverley <andy@andybev.com>,
Mail List - Netfilter <netfilter@vger.kernel.org>
Subject: Re: redundancy with Adsl modem
Date: Fri, 06 Jan 2012 18:12:03 +0100 [thread overview]
Message-ID: <4F072B63.7060609@freemail.hu> (raw)
In-Reply-To: <CAMTjHrw4Rrb7c4h5Sv2jRctiUcqWD8O-xZx54M9Dp5jc8qZYdQ@mail.gmail.com>
Hi,
> yes, I need redundancy. when an line adsl come down all traffic go to
> other line adsl. I couldn't have done this on linux machine. if you
> has any how to about please post here.
How do you want to do that???
If you have two connections then you have two external IP-s...
If one goes down then you can not simply use the other one...
Just think about these steps:
In normal connection:
1. a local host (A - 192.168.1.1) sends a packet from LAN to an external
host (C - 8.8.8.8)
2. the firewall applies source NAT to the packet and sends it out as if
it were coming from the firewall's first external IP (B1 - 1.1.1.1)
3. C sends back a reply to B1
4. B1 forwards it with destination NAT to A.
5. go to step 1. or close the connection
If the line goes down between step 2 and step 3 then the reply packet
will never get back to B1 and A (because the line is down) !!!
If the line goes down after step 4 then you can send it out on the
second extrenal IP (B2 - 2.2.2.2) but C will see it as a NEW connection !!!
So I think that your request is impossible on IP level.
However you can use a proxy or a mail server, etc. etc. etc.
Swifty
next prev parent reply other threads:[~2012-01-06 17:12 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-03 1:54 redundancy with Adsl modem Usuário do Sistema
2012-01-03 7:14 ` Andrew Beverley
2012-01-03 15:18 ` Usuário do Sistema
2012-01-03 23:58 ` Andrew Beverley
2012-01-04 0:17 ` Usuário do Sistema
2012-01-04 1:58 ` Lloyd Standish
2012-01-04 9:09 ` Gáspár Lajos
2012-01-04 11:16 ` Usuário do Sistema
2012-01-04 14:08 ` Lloyd Standish
2012-01-04 18:00 ` Gáspár Lajos
2012-01-04 20:15 ` Usuário do Sistema
2012-01-04 20:55 ` Lloyd Standish
2012-01-06 17:12 ` Gáspár Lajos [this message]
2012-01-06 18:16 ` Lloyd Standish
2012-01-10 0:20 ` Usuário do Sistema
2012-01-17 16:09 ` Gáspár Lajos
2012-01-17 17:08 ` Usuário do Sistema
2012-01-04 20:55 ` Lloyd Standish
2012-01-04 21:01 ` Lloyd Standish
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