[MUD-Dev] Mud Network Setup

Joe Andrieu joe at andrieu.net
Sat Mar 4 05:50:09 New Zealand Daylight Time 2000


> -----Original Message-----
> From: mud-dev-admin at kanga.nu=20
> [mailto:mud-dev-admin at kanga.nu]On Behalf Of
> Steve Boleware
> Sent: Friday, March 03, 2000 11:14 PM
> To: mud-dev at kanga.nu
> Subject: Re: [MUD-Dev] Mud Network Setup
>=20
>=20
> hello, i was under the impression that the bandwidth that=20
> you got from DSL
> depended on the package that you got from the phone company..
> I.E. i myself am getting what they call the "Bronze Plus"=20
> package which
> gives me
> up to 768 up/128 down. but at no time does it promise that=20
> the "minimum"
> will be there at all..
> ie can go down to 0 at bad times.. i seem to average around=20
> 240k (lousy i
> know)
>=20
> --
> Steve (rest of sig lost ^_^ )
>=20

Steve's right. There really isn't "gauranteed bandwidth" anywhere.  The =
Internet "backbone" is just a bunch of shared switches: NAPs (Network =
Access Points) or MAEs (Metropolitan Access Exchanges?). At every =
connection after that, each smaller ISP or company or individual buys =
from the ISP "upstream"*  Pretty much all of these downstream services =
are bundled together by their upstream provider, agregating bandwidth, =
so that a 45 Mbps upstream might service twenty to fifty or more 10 mbps =
downstream connections. And those 10 Mbps often provide T1 service =
(~1Mbps) to twenty to 100 or more downstream customers. =20

       MAE East ------------------------------------            MAE West
           |   \                                    \            /  | \
           | /--\------------------------------------\--- ------/   |  \
           |/    \                     /--------------\-------------    =
\
          BBN     \--------------Sprint               UUNET-------------
         / | \                    / | \                   / | \
        /  |  \                  /  |  \                 /  |  \
       /   |   \                /   |   \               /   |   \
      /    |    \              /    |    \             /    |    \
     /     |     \            /     |     \           /     |     \
 Phone    ISP   Ford      Earthlink
  Co.    / | \  Motors     / | \              =20
        /  |  \           /  |  \             =20
       /   |   \         /   |   \          =20
      /    |    \       /    |    \         =20
     /     |     \    Fred  Mary  JQ Public
        /  |  \         =20
       /   |   \        =20
      /    |    \       =20
     /     |     \      =20
  Random  Local  etc.
   Co.     ISP
          / | \ =20
         /  |  \         =20
        /   |   \        =20
       /    |    \       =20
      /     |     \      =20
   Bob's   Local  Colocation
  Bait &    Co.
  Tackle

[*This is mostly true. Some companies, like InterNAP route around the =
public NAPs, but the model still works for understanding bandwidth.  And =
it is possible to pay for preferential routing so that into a particular =
network you can get gauranteed bandwidth. But for the most part...]


[Egads!  Does insomnia have no cure?!?]


Because most internet traffic is "bursty", this works. Net traffic is =
uncoordinated and predictably inconsistent. So when you add it all up, =
most users get most of their bandwidth most of the time, even though at =
no point can any amount of throughput be guaranteed (because there is no =
"there" to which to gaurantee such throughput).  This is different than =
dedicated WAN connections such as Frame Relay or ATM networks. These can =
in fact gaurantee bandwidth. And as a result, they are notoriously =
inefficient, which is why IP is the world standard for large networks.

As for DSL vs. Cable Modems, it's a matter of _where_ the agregation =
happens.  With Cable Modems, everyone in your neighborhood is physically =
on the same link. You immediately share bandwidth as soon as the line =
leaves your home.  DSL has a dedicated link to the phone company, but no =
real gaurantee of how many DSL lines the phone company might combine to =
share the upstream bandwidth.  A cable company could connect 45 Mbps =
upstream spread across 50 households (unlikely)--while a DSL provider =
agregates 1,000 households to the same 45 Mbps.

Therefore, the only certain difference is that cable companies have a =
harder time upgrading bandwidth because they have to go out to the =
physical infrastructure, where DSL providers can just buy more upstream =
connectivity and bigger switches. You can ask about ratios for =
agregation upstream, but I'd be surprised if they'll tell you.

A long answer to a short question.

-j





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