[SATLUG] Wifi (Bandera County)

[Brad Knowles]

On 9/2/07, Borries Demeler wrote:

>  Has anyone ever tried to channel-bond dialup modems?

Cisco routers can do this.  You just need multiple serial ports, to 
which multiple modems are connected.  Route over them using OSPF, and 
you're done.

>  I wonder what kind of bandwidth can be gotten by doing that.

The bandwidth is not the problem.  The problem is latency -- modems 
add on a minimum latency of about 250ms, on top of whatever you get 
from the upstream network.  To put that in perspective, I get ~150ms 
latency when pinging the python.org servers in Amsterdam 
(Netherlands) from my cablemodem here in Austin.  For ~200ms, I can 
hit Russia (allofmp3.com).

Keep in mind that TCP/IP is a bandwidth/latency product protocol, so 
as the latency increases, the maximum possible bandwidth over that 
connection falls.  You might have lots of excess bandwidth that is 
available for other connections, but on a per-connection basis, your 
bandwidth will drop precipitously as the latency goes up.

>  In areas where high-speed internet is not available multiple
>  phone lines may be an option?

A lot depends on your upstream.  Channel bonding of modems is 
something that was done many years ago, back before "real" upstream 
networks existed in most places.  But you don't hear about anyone 
doing that kind of thing anymore, because the latency was just so bad.

-- 
Brad Knowles <brad at shub-internet.org>
LinkedIn Profile: <http://tinyurl.com/y8kpxu>