BRI and PRI Interfaces
Table 4-2 compares the capabilities of BRI and PRI interfaces.
Table 4-2 BRI and PRI Interfaces
Capability BRI T1 PRI E1 PRI
B-Channels 2 ¥ 64 kbps 23 ¥ 64 kbps 30 ¥ 64 kbps
D-Channels 1 ¥ 16 kbps 1 ¥ 64 kbps 1 ¥ 64 kbps
Framing 16 kbps 8 kbps 64 kbps
Total Abstracts Rate 160 kbps 1.544 Mbps 2.048 Mbps
Framing NT, TE Frame SF, ESF Multiframe
Line Coding 2B1Q or 4B3T AMI or B8ZS HDB3
Country World North America, Japan Europe, Australia
Using ISDN for articulation cartage has these benefits:
■ ISDN is absolute for G.711 beating cipher accentuation (PCM) because anniversary B approach is a
full 64 kbps with no beggared bits.
■ ISDN has a congenital alarm ascendancy agreement accepted as ITU-T Q.931.
■ ISDN can back standards-based articulation features, such as acceleration dialing, automated
operator services, alarm waiting, alarm forwarding, and geographic assay of customer
databases.
■ ISDN supports standards-based added dial-up capabilities, such as Group 4 (G4)
fax and audio channels.
With ISDN, user abstracts is afar from signaling data. User data, such as the payload
from a digitized buzz call, goes to a 64-kbps B channel, and signaling data, such as a
call bureaucracy message, goes to a D channel. A distinct D approach supports assorted B channels,
which is why ISDN account is accepted as CCS.
The bead and admit adequacy allows for activating multiplexing of B channels between
different interfaces. This affection is accessible alone if all interfaces use a accepted clock
source, as is the case with Integrated Account Routers (ISRs).
Figure 4-6 shows an archetype of the bead and admit feature. The channels of an ISDN PRI
connection from an Internet account provider (ISP) are breach up. Twenty-one channels are
routed to addition PRI interface of the router affiliated to a PBX, and two channels are
routed to a BRI interface affiliated to an admission server.
Using ISDN for articulation cartage has these benefits:
■ ISDN is absolute for G.711 beating cipher accentuation (PCM) because anniversary B approach is a
full 64 kbps with no beggared bits.
■ ISDN has a congenital alarm ascendancy agreement accepted as ITU-T Q.931.
■ ISDN can back standards-based articulation features, such as acceleration dialing, automated
operator services, alarm waiting, alarm forwarding, and geographic assay of customer
databases.
■ ISDN supports standards-based added dial-up capabilities, such as Group 4 (G4)
fax and audio channels.
With ISDN, user abstracts is afar from signaling data. User data, such as the payload
from a digitized buzz call, goes to a 64-kbps B channel, and signaling data, such as a
call bureaucracy message, goes to a D channel. A distinct D approach supports assorted B channels,
which is why ISDN account is accepted as CCS.
The bead and admit adequacy allows for activating multiplexing of B channels between
different interfaces. This affection is accessible alone if all interfaces use a accepted clock
source, as is the case with Integrated Account Routers (ISRs).
Figure 4-6 shows an archetype of the bead and admit feature. The channels of an ISDN PRI
connection from an Internet account provider (ISP) are breach up. Twenty-one channels are
routed to addition PRI interface of the router affiliated to a PBX, and two channels are
routed to a BRI interface affiliated to an admission server.
194 Authorized Self-Study Guide: Cisco Articulation over IP (CVOICE)
PSTN
Si
T1 Connection to
ISP
23 B Channels
Connection to
PBX 21 B
Channels
BRI Connection
to Admission Server
2 B Channels
Access
Gateway
V
PBX
Channels
Split Up
Figure 4-6 Bead and Insert