Mailing List Message #14866
From: Bill Cole <>
Subject: Re: Wandering off-topic: Speedstream 5861 (was Re: Authentication Attempts)
Date: Wed, 1 Dec 2004 22:39:57 -0500
To: SIMS Discussions <>
At 6:33 PM -0700 12/1/04, Warren Michelsen  imposed structure on a stream of electrons, yielding:
At 7:40 PM -0500 12/1/04, Bill Cole issued a series of ones and zeros which decoded as:

When a device says it's a 'DSL' router, that's just Ethernet, right?

No, it usually means it has some form of actual DSL support.

But what's DSL? Digital Subscriber Line, yeah, but what IS it? I
thought it was just Ethernet over phone lines, essentially.


It's a system for using high-frequencies over standard 2-wire phone lines (in the 3MHz range, as I recall... ) to carry digital signals. It is a bit like a different sort of modem standard that uses frequencies far outside of the audible ones used for voice, so you can have both voice and data on the same old-fashioned simple copper telephone pair. DSL  is even lower-level than the stack of standards we generally refer to as 'Ethernet' and is more like the slices of the Ethernet standard that defines how to put a signals on a piece of CAT-5 or ThinNet coax cable.

In addition, DSL is purely a point-to-point serial model: where Ethernet is premised on having many peers hooked into what amounts to a broadcast medium, with a complex system for traffic control, DSL is defined for 2 partners talking to each other in defined frequency ranges on one end-to-end pair of copper wires.

 If it's
not, then I really don't want a Speedstream, right?

Right. If your upstream link is not DSL, you do not want any DSL-oriented device.

My 5861 has 4 Ethernet ports, but that's really just a simple dumb hub. The other side of the router is a DSL port: standard phone wire and it literally plugs straight into the same jack on the wall where an identical port goes to a perfectly normal phone (with a low-pass filter on the phone wire so that the gross electronics of the phone don't screw with the DSL signal.)

I thought a DLS
modem just output Ethernet. Or are you saying that the Speedstream
5861 interfaces between the phone line and an Ethernet network?


For example, the Speedstream 5861 has a direct interface to my DSL
link and handles all of the DSL connection setup from DMT up
through PPPoE.

Reading the spec sheets is always mandatory...

Of course, but since I'm unaware (apparently) of what DSL is, the
spec sheet does me no good.

I have plain vanilla 10/100 Ethernet coming in as my Internet
connection. I want to install a router/firewall device to keep out
spammers and such persons as I may come to despise for annoying my

I'd like to be able to block all traffic from specific IPs or just
selected ports from specific IPs. Will a Speedstream do that for me?

No, because it has the wrong sort of interface. It also would be a fair bit pricier than you need.

Will a LinkSys BEFSR41 or BEFSX41 do it?

This is where things get screwy. I am not familiar with either of those so I went to the Linksys site, and I see things they give names like "Cable/DSL Router" which is simply confusing. From what I can tell, those particular devices look to be more oriented towards protecting a home network from the miscreants inside rather than from known miscreants outside. It looks like you'd have to hack something up like adding static routes to their address space with bogus gateways, which is a nice functional traditional way to do IP blocking, but it a bit of an unobvious hack.

Bill Cole

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