[ale] OT: ADSL modem bottleneck

Dow Hurst dhurst at kennesaw.edu
Mon Mar 1 14:45:41 EST 2004


How expensive are the ADSL cards to put in a Linux box? 
I've seen them in Sysadmin magazine now and LinuxFormat from 
some hardware provider.  I've thought that building up the 
whole single purpose device under Linux would be nice for 
the control of the connection.  The little ADSL routers 
available never seem to be able to keep the connection from 
hanging which then requires recycling the power on the them.

Also, we use Linux router/fw's based on Slackware from 
Fly-By-Day for hooking up to the ADSL ethernet based modems 
from Bellsouth, Earthlink, and the cable modems from 
CharterCable.  I've also got a SMC Barricade wifi ADSL 
router/fw box that works fine with Earthlink, but I've put 
the Fly-By-Day fw behind it to protect the research based 
home network.  I don't trust the wifi or home network in 
that case at all.

The SMC Barricade series and the 2Wire series of 
multifunction router/wifi/HPNA/fw/ADSL devices seem to be 
able to be updated remotely by the respective companies for 
OS and IDS patches.

Bob is always on top of the Fly-By-Day fw's so I don't have 
to worry about them.  He has some nice packages for email 
with spam control, and VPN solutions too.

The most robust solution we have so far for uptime is the 
Charter cable setup where the cable modem gets a static IP 
and the Fly-by-Day fw router protects the home network.  The 
PPPoe stuff with BellSouth and Earthlink tends to have PPP 
downtime.  However, the Fly-By-Day fw/routers give us enough 
control to be able to troubleshoot effectively when stuff 
dies.  It is always the provider, never the Linux box now.
Dow


Mike Millson wrote:
> On Mon, 2004-03-01 at 09:39, Bjorn Dittmer-Roche wrote:
> 
>>On Sun, 29 Feb 2004, Mike Millson wrote:
>>
>>
>>>On Sun, 2004-02-29 at 09:41, Bjorn Dittmer-Roche wrote:
>>>
>>>>But DSL is only half duplex, so would a half duplex 10BaseT actually slow
>>>>you down?
>>>
>>>Are you saying that DSL and ADSL in and of itself is only capable of
>>>half duplex? It's not just a pipe between the router and the central
>>>office? You can only be uploading or downloading at a given time? Or are
>>>you saying that the router itself, like a hub, is half duplex?
>>
>>That's what I read, but I'm having trouble varifying that now. Some sites
>>seem to think that duplex means symetric. Anyway, I will just say that I
>>*think* DSL is half duplex and leave it at that. Someone else know better?
>>
> 
> I did some searching around, and I'm convinced that the ADSL that I have
> is full duplex.
> 
> I'm not so sure about IFITL. It may be half duplex.
> 
> And I found this in the Linux DSL HowTo:
> "Most DSL modems and routers typically are set to half duplex."
> 
> No doubt the 10BaseT connection on my ADSL router is half duplex.
> 
> It seems to me that the Alcatel 1000 router itself is the bottleneck.
> The ADSL connection my only be 256 kbps, but it is full duplex. The
> router can do 10 Mbps, but it's only half duplex.
> 
> Anyone know of a full duplex ADSL router that they would recommend using
> w/ BellSouth ADSL?
> 
> Mike
> 
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> http://www.ale.org/mailman/listinfo/ale
> 

-- 
__________________________________________________________
Dow Hurst                  Office: 770-499-3428            *
Systems Support Specialist    Fax: 770-423-6744            *
1000 Chastain Rd. Bldg. 12                                 *
Chemistry Department SC428  Email:   dhurst at kennesaw.edu   *
Kennesaw State University         Dow.Hurst at mindspring.com *
Kennesaw, GA 30144                                         *
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