[LARTC] Re: Load Balancing 4 cable modems, followed nano.txt

[Julian Anastasov]

	Hello,

On Mon, 17 May 2004, Charles-Etienne.Dube wrote:

> I did some tests with 2 cable modems, but now it is installed in a production
> environment with 4 cable modems.  At first, everything seemed to work  fine..
> But now I had a couple of users tell me that some web pages were
> not available while others were, and it semms to be a masquerading problem
> since when I downgraded the system to one cable modem and normal routing
> table with only one default gateway everything started working fine again (like
> before). I am sure that the non-working URLs were valid sites that were available
> at the time (ex: www.yahoo.com; www.google.com; www.hotmail.com).
>
>
> Here are my questions :
>
>
> 1 - Did I use to right patch ? I used "routes-2.4.20-9.diff"

	It is the right one

> I tried to apply "05_nf_reroute-2.4.20-9.diff" Even if I'm used to
> patching kernels, I don't understand that much about this process, and
> the patch programm was giving error messages, while the one I use was applying
> without any error messages.

	Stick with "routes-*.diff" because it is not enough to apply
05_nf* patch, there are two diffs to apply before it.

> 2- Should I  use :
>
> iptables -t nat -A POSTROUTING -o IFE1 -s NWI/NMI -j SNAT --to IPE1
> iptables -t nat -A POSTROUTING -o IFE2 -s NWI/NMI -j SNAT --to IPE2
>
> instead of :
>
> iptables --table nat --append POSTROUTING --out-interface eth1 -j MASQUERADE

	-j MASQUERADE works for dynamic IPs and is recommended
for complex routing situations when using the "routes-*" patches

> Can anybody elaborate on the difference between these 2 commands.
>
> 3 -  The 4 cable modems have a different IP, but two of them obtained an
> ip in the same address class so they both have the same gateway. In my
> script I treated them as if they were each on different gateways and I see
> traffic going on the 4 modems so I don't think this is an issue but I'd
> like to have some advice about this.  What happens if all the IPs
> are renewed at the same time and all 4 modems obtain an IP in the same
> class with same gateway... will it still work ?

	If the gateways are same I assume they are on different
interfaces.

> 4 - do you think 4 cable modems is too much, has it been tested ?

	I do not remember how many nexthops allows the ip utility for
multipath routes but 16 should be possible.

> Help with this case would really be appreaciated,  I am ready to give
> any details that would be necessary for you to guide me further..

ip addr
ip rule
ip route list table all

> Thank You
>
> Charles-Etienne Dube

Regards

--
Julian Anastasov <ja@ssi.bg>