HP MSR2000/3000/4000 Router Series Layer 2 - WAN Configuration Guide

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Figure 27 shows that the ISDN D channel protocol stack has three layers:
• Q.921—A data link layer protocol of the D channel. It defines the rule for Layer 2 information
interchange through D channel from the user to a network interface and supports the access of a
Layer-3 entity Q.931.
• Q.931—A network layer protocol of the D channel. It provides a method of establishing,
maintaining, and terminating network connections between communication application entities.
• Call control (CC)—A further encapsulation of Q.931, which forwards the message from the network
side to CC, and CC then performs information interchange with higher layer applications such as
DDR and voice.
Figure 27 ISDN D channel protocol stack
ISDN network diagrams
Figure 28 and Figure 29 show ISDN network diagrams for data services and voice services, respectively.
Figure 28 Data ISDN network diagram
Figure 29 Voice ISDN network diagram
ISDN configuration task list
This document describes ISDN configurations on a BRI or PRI. For more information about BRIs and PRIs,
see Interface Configuration Guide.