ISDN and LEASED LINE CONNECTION

[kaziasif78]

Hi all,
What is the difference between an ISDN and an leased line connection,And what all we need to install (components),Plz in brief.

Thanx

 

[scauffiel]

The difference? I dunno. I lease an ISDN line for one of my sites... So I'm not real sure what you're asking... You'll have to either buy or lease an ISDN modem that is 'compatible' with your service, and then set up a 'dial up connection to get online. If you're talking 'leased line' as in T1/T3 or something along those lines, I can't help you there becaue I've never done that.

Steve

 

[3DPhreak]

I install leased lines all the time for customers. A leased line is a dedicated point-to-point circuit (usually a DS1 (T1)) between two locations.

You will need a CSU/DSU to connect to it.

I am assuming you have a router that needs to connect to it?

If it is a Cisco access router like a 1700, 2600, etc series of router, you will need a WIC-1T with an external CSU/DSU. Or you can get a WIC-1DSU-T1-V2= (1-Port T1/Fractional T1 DSU/CSU WAN Interface Card: Ver. 2) that has a CSU/DSU built in - I recommend this option.

I will need to know more specifics before I can say anything for sure though. Your question was a little vague.

 

[Garion]

Think of ISDN as a "digital phone line." An ISDN line is made up of two unique 64Kb/s channels which can be combined together to form a single 128Kb/s circuit. There's also another channel on the ISDN that's used for signaling. ("Hey, line #2 is ringing" or "send a busy signal if you just called line #1 - It's in use" since there are no electrical signals like you have on a regular phone line that handle busy signals and rings. ISDN lines must be dialed and be answered by another ISDN line or a special circuit (called a PRI, a bundle of ~11 ISDN lines combined together) when used for data. In short, think of it as a special and faster dial-up modem.

A leased line is a dedicated circuit - An extension of your network that must be controlled by CSU/DSU's (which kind of act like modems but there's no dialing involved) and typically routers. They are always always connected. Common leased lines are old and slow 64Kb/s circuits, T1's (1.5Mb/s) and DS3's (also called T3's) at 45Mb/s. T1's and DS3's can also be "fractional" where you buy the circuit in chunks - A T1 is made up of 24 64Kb/s lines (Noticing a trend here?). You can buy a half of a T1 at 768Kb/s, a 256Kb/s fractional T1, a 1024Kb/s fractional T1, etc. A DS3 is made of 28 T1's, and it can also be purchased in fractions.

There are some other types of leased lines, and the definition is somewhat blurry. 64K/T1/DS3 are the "classic" ones, but DSL is definitely in the same general territory - Always on, dedicated connection, etc. A cable modem is different - It's more like an Ethernet network run over your cable system.

Because I can't stand to just dump this information on you without something to tie it all together..

A T1 is a "bundle" of 24 channels. These can either be used for data (Each channel is 64Kb/s) or a single normal voice line like you have at your house. A DS3 is a bundle of 28 T1's, meaning 45Mb/s or 672 voice lines. ISDN is similar. A PRI is just like a T1, except it only has 23 channels that are useable - The 24th is used for signaling.

Hope this helps!

- G