ADSL Modem terminology

[Tempest]

Please can someone clarify the difference between an ADSL modem and an ADSL router, and all the different kinds (like "over POTS" and "over ISDN" etc.)

I am still just learning about ADSL, and so any help would be appreciated

 

[Tharaxis]

ADSL Modem:

This is very similar to your standard dial-up modem, it's a piece of hardware which connects to a single machine which then allows that machine access to the internet, any form of internet connection sharing must be done on the machine accessing the internet.

ADSL Router:

This is effectively a network switch with a built-in ADSL modem, the switch does all the dialling in and sharing of the internet connection to those machines connected to it, ADSL Routers also tend to come with a firewall (stateful packet inspection or NAT) and allow you to configure them via either Telnet or a web interface. There's no need to set up anything on any of the PC's on the network (other than telling them to look for an internet gateway on the network), the Router handles it all.

Over POTS:

POTS - Plain Old Telephone System - this is what you, me, Telkom, whoever uses as a telephone network, it consists of copper cabling and all the other funny telephone system stuff that Telkom doesn't want you to know about - This just means that your ADSL connection functions over a standard telephone line, much like most ADSL installations Telkom does.

Over ISDN - This I may be wrong with, correct me if it is, I'm taking a stab in the dark.

This, similar to Over POTS, utilizes any ISDN technology you may have - this is most useful for those who have ISDN and are now looking into "upgrading" to ADSL instead of having to have everything removed and replaced (thereby being costly to the end user), other than that, there's little in the way of added benefit.

 

[Tempest]

thanks, i was just confused about whether or not routers have modems built in or not (cos some sites can be misleading)

 

[kaspaas]

Hi,

I've only worked with ADSL modem/routers in the office environment, and know nothing about the standalone modem.

Do they also offer built-in firewalling?

It is something I like about most modem/router combo's - you don't need to worry about attacks from outside - provided you set your router up correctly.

 

[Tharaxis]

Tempest: I suggest you DO still keep an eye on the specs when it comes to "ADSL Routers", some seem to classify themselves as ADSL routers but do NOT include an ADSL modem, instead requiring you purchase a separate modem to hook up to the router, so make sure you're buying an all-in-one package.

kaspaas: No, ADSL modems, much like any other standard dial-up modem rely on the PC they are connected to to offer firewalling services, connection sharing, port address translation, etc. in the case of an ADSL router with a built in modem, the router itself assumes the responsibility your computer would have had.