[plug] 2 modems, eql etc

[Leon Brooks]

Leon Brooks wrote:
> 
> "Shackleton, Kevin" wrote:
> > I've looked around for something in the LDP about putting together a couple
> > of modems and eql for extra bandwidth, without success (except in a general
> > sense).  I have to set up a proxy for the local business expo and hope to
> > offer 2 * 56K.  If it doesn't work they'll only get 1 * 56K!
> 
> I've done it. It's not pretty, but it works.

Now, researching the site that used to be two-modems-plus-EQL...

I think I had to set a kernel onfiguration parameter, but cannot
certainly remember. I also had to find (and compile, because the binary
was expecting libraries that I didn't have) a small program called
eql_enslave. This was then used as follows:

1. dial first link, ppp0, get assigned an IP (hereinafter, $PPP0_IP)
2. dial second link, ppp1, get assigned $PPP0_IP again
3. ifconfig eql $PPP0_IP mtu 1500 up
4. eql_enslave eql ppp0 $PPP0_CONNECT_RATE
5. eql_enslave eql ppp1 $PPP1_CONNECT_RATE
6. manually fix the routing to use the eql device instead of ppp0
   (route del default; route add default gw $PPP0_IP dev eql; etc)

I presume that the other end of the deal is pretty much the same. If a
link goes down, the eql device keep working with less links until you
re-"eql_enslave" another one back into the collection. The rate is used
for load balancing, and for this system we rate-limited the modems (to
44kb/s) for more reliable connections, and just assumed that they'd
connect at 44000, but EQL's load balancing appears to get a bit extreme
if the actual rate of the two modems is different, and winds up all
lopsided (although this may have been the fault of the Lincoln
PortMaster 3 at the other end).

I've put a copy of the binary (compiled under Mandrake 6.1, should work
for RedHat 6.[0-2] and Mandrake [67].[01], will probably work for any
other recent distro) at http://servers.with.a.smile.fdns.net/eql_enslave
and the original package at
http://servers.with.a.smile.fdns.net/eql-1.2.tar.gz in case you can't
find it elsewhere.

-- 
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