Content











4.2



ISDN Protocol Layers
 



 


4.2.1



ISDN Layer 1
 







ISDN at Layer 1 is responsible for
switching the carriers circuits to build a
connection. ISDN Layer 1 also supports the attachment of various ISDN
functional devices. Both the B and the D channels share this physical
layer. Layer 1 ISDN standards include the following:

I.430 for BRI, which defines the
communication across the S/T reference point
I.431 for PRI, which is a
full-duplex, point-to-point, serial, synchronous connection

ANSI T1.601 for BRI, which defines
the communication across the U interface for North America



















 



Web Links

Integrated Services Digital Network



http://www.cisco.com/univercd/cc/td/ doc/cisintwk/ito_doc/
isdn.htm