ISDN Ref points: uses 4 Ref points to define logical interfaces. R : defines the ref point between non ISDN eqpt & TA,

S : defines the ref point between user terminals & an NT2, T : defines the ref point between NTI & NT2 devices,

U : defines the ref point between NTI devices and line term eqpmt in a carrier net (only in N. America)

ISDN protocols: E-series specifies ISDN on existing tel network, Basic telephone services.

I-series specifies Concepts, terminology and services, Q-series specifies switching and signaling.

Basic Rate Interface (BRI) : 2B+1D Chl. 2x64kb B Chl. carries Data, 16kb D chl. carries cntrl & signaling info.(tot 144kb). D chl signaling proto spans phy, dll, Net layers. Config BRI: Need SPID (Service Profile Identifiers), one for each B chl.

Its like Tel no. for each B chl. ISDN Device can access BRI service only after giving SPID no. to the ISDN switch.

# config t, # isdn switch-type basic-dms100, # int bri0, # encap ppp, # isdn spid1 77545, # isdn spid2 77546

Primary Rate Interface (PRI): 23B+1D64 chl. (1.544mb-T1), 30B+ 1D64 (2 mb-E1)

Config PRI: for each ISDN PRI int, need to specify Data link specific info for the T1 controller, this way PRI commtes with ISDN switch, Framing & line coding info is essential. # config t, # controller T1 1/0, # int pri0, # framing esf,

# linecode b8zs, # pri-group timeslots 1-24, Extended Superframe Framing (ESF) is used in T1 ckts, consists 24 frames of 192 data bits each, with bit 193 provides timing & other functions. B8ZS is a binary eight-zero substitution line-coding mechanism guarantees delivery of data of 8 cont. zeros. Time slots 1-24 defines ISDN PRI time slots 1 to 24.

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