[clue-tech] DSL providers

[Hex Star]

On 2/15/07, William <wwcluetech1 at kimballstuff.com> wrote:
>
> Hex Star wrote:
> > I find it funny how people constantly point out that neighbors share
> > the same pipe, while the same is true for any other broadband
> > connection except instead of it being shared at the neighborhood area,
> > you're sharing the data center connection...so no matter what there's
> > still a bottleneck...
> This very topic is the basis for many debates.  In the hopes of avoiding
> a religious fight while helping you understand why this is "constantly"
> pointed out, I'll explain in the easiest way I can (taking liberties to
> avoid as much complexity as possible, and being verbose in the hope that
> I can head-off any anticipated questions).  For reference, I will be
> expanding the examples set forth in [Computer Networking, A Top-Down
> Approach Featuring the Internet; 3rd Edition; pages 26-28].  To brief
> the point, HFC/Cable lines are clearly defined as being "shared" while
> DSL lines are clearly defined as being "dedicated".  I'll illustrate
> why, after some definitions that will be used to draw an analogy between
> Cable and DSL.
>
> I don't know whether you already understand the fundamental difference
> between a "network hub" and a "network switch", so I'll give a
> rudimentary contrast.  Please jump ahead if you're already clear on the
> distinction.  First, both a hub and a switch are (generally speaking)
> repeaters that enable several network devices to communicate with one
> another by repeating packets received on one line to one or more other
> lines.  They handle the repeating task differently, however:
>
> * A hub repeats every packet it receives onto every connected line,
> verbatim.  Consequently, every network device that is connected to the
> hub must receive every single packet that is sent to/through the hub.
> Each network device simply disregards packets not destined for
> themselves.  Note that there is a time cost when disregarding undesired
> packets.  Because of this mass-broadcasting-like behavior, it is very
> easy to snoop network traffic at a hub.
>
> * A switch however, repeats each packet only to the specific destination
> line.  Each network device connected to the switch receives only those
> packets that are sent to that specific device.  Consequently, network
> traffic is far more efficient on networks using switches than those
> using hubs.  While possible for certain types of traffic, snooping
> network traffic at a switch is not nearly as easy as snooping at a hub.
>
> Given these definitions, I'll draw the relevant analogy to Cable and DSL
> (very loosely speaking -- this is an analogy).
>
> * A Cable user is (effectively) connected via a hub that is shared with
> all their neighbors.  When using Cable at home, all of your neighbors
> can snoop your traffic because every packet that you send and receive is
> bounced off all of your neighbors.  The obvious consequence of this is
> that every "active" user is sending traffic to your home (doubly so when
> you consider that their output packets are hitting you *and* their input
> packets are hitting you), reducing your bandwidth capacity for as long
> as they are active.  This is why the cable line is considered "shared".
>
> * A DSL user is (effectively) connected via a switch that is discrete to
> the line provider.  When using DSL at home, your neighbors cannot snoop
> your traffic.  Packets that you send or receive are piped strictly
> between you and your ISP.  Your neighbor's packets never hit your home,
> so they never directly affect your bandwidth capacity.  This is why the
> DSL line is considered "dedicated".
>
> Note that the "bottleneck" to which you refer occurs at the ISP's
> internal and perimeter routers (or even higher as dictated by network
> health) where many network are combined.  These routers are massive and
> handle incredible amounts of traffic each day.  The likelihood of any
> single user significantly affecting other same-ISP users in either the
> Cable or the DSL case is negligible.  Consequently, a DSL user simply
> does not affect neighbor DSL users as much as a Cable user affects their
> Cable neighbors.
>
> > and heh, just looked at FRII and they're a DSL provider...that IMO
> > means they're even less flexible then a cable broadband ISP like
> > Comcast because the farther away you are from their central office the
> > slower your connection which is not the case with cable broadband...
> While what you say is true about DSL bandwidth rates dropping
> significantly as the end-user is positioned further and further away
> from the nearest DSL Point-of-Presence, make no mistake.  Distance
> affects the propagation rate of every line, generally manifesting as
> round-trip latency for everyone as they move further from their
> respective Points-of-Presence.  Cable is no exception.  While the
> effective bandwidth fall-off rate is slower for Cable than for DSL, the
> DSL rate is guaranteed once determined. Cable makes no such guarantee of
> bandwidth because it cannot (don't let the marketers fool you).  As soon
> as a Cable user starts downloading, their neighbors' download rate
> suffers immediately and sometimes, significantly.  Additionally, Cable
> users are faced with the question, "Do I really want my neighbors to see
> what I'm downloading?"  :)  [Yes, I'm trying to inject some humor after
> all that technical dialog.]
>
> Hope this helps,
>
> William
>
>
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Is it really true that all broadband modems in a neighborhood receive the
packets from every other user in the neighborhood? I've also heard that if
you directly connect to the cable modem that if you use windows or some
other smb compatible browser you can see al the computers that are on in
your neighborhood? I'd assume a router, like I use is a good measure to
protect against anyone being able to access my computers without my
permission right (since it assigns internal dynamic IPs and requires port
forwarding for outside requests to reach any inside computer)?

As for the neighbor issue...true it may be closer...but still todays ISPs
with todays technology are able to provide a ton of bandwidth for each
neighborhood so this is rarely a issue..it sure hasn't ever been a issue for
me
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