ISDN Question (Spawned from Article)

I read the article on the basics of ISDN however there is one thing that has me confused. Everyday I work with clients who are having all data T1's install for general Internet access. They are usually terminated on routers that we support however I am curious if you would consider these types of products we are receiving has PRI T1's . They terminate into regular Cisco Internal CSU/DSU WICS.. are these technically PRI's ?

Looking that the interface configuration there is nothing specific for ISDN, just HDLC ..etc to the provider

Are there two types of "T1" products ? I have heard of "CAS" and ISDN "PRI" difference?


Can someone shed some light here for me? and help me visualize the differences.

Thanks!

Kenny

Hi,

Well T1/E1 is basically a type of a link. E1 is the European/Asian kind and the T1 is the North American and the Japanese type. The E1 has a bandwidth of 2 Mbps and the T1 has around 1.5 Mbps. PRIs can be both E1 or T1 depending where you are located. If you have a T1 line then the number of channels are 23 and if you have a E1 line then you get 30 channels.

Hope that clears something,

Hi,

CAS and ISDN refer to the signalling protocols used to carry call state & feature information.

CAS = Channel Asociated Signalling

ISDN = Intgrated Service Digital Network

CAS is very basic and can be thought of as the first digital signalling protocol to be used in Telecommunicatons

Hope this helps.

R

thats what i thought but wasn't 100% sure. The thing that confused me with this post was

Looking that the interface configuration there is nothing specific for ISDN,

Seemed a little odd. Do you know if CAS still uses the ISDN commands to configure the serial link ?

As the Article states, it can use PPP or HDLC as its encapsulation protocal so the fact its using hdlc isn't that odd as this is just the point-to-point encapsulation thats being used.

It does have me curious if no ISDN commands are in use though.

Hi,

CAS predates ISDN by approx 5-10yrs. So CAS doesn't use ISDN commands at all.

CAS signalling is related to basic call setup & clear down commands and really doesn't have any in built capability for call features (i.e. channel bonding).

I guess in a data network as you are using the CAS circuit for bandwidth then this is all that is needed.

br

R

Cheers fella, that makes more sense