Chapter 6. Configuration61200051L1-1D ISU 2x64 Dual Port ISDN Service Unit User Manual 61When originating calls to unknown units, the ISU begins its pro-tocol selection based on its local Call Type. (Data 64k is used forFALLBACK when selected from the Quick Setup menu.) Uponconnection at 64k Call Type, BONDING, V.120, and PPP areattempted. If connection is not made at 64k, the ISU attemptsanother call at 56k Call Type. If the protocol cannot be negoti-ated, the ISU hangs up the call.Point-to-Point (PPP) Async-to-SyncPPP provides a standard method for transporting multi-protocoldatagrams over point-to-point links. The ADTRAN PPP async-sync protocol allows the ISU 2X64 and a PC or Macintosh® run-ning PPP software, to communicate with a PPP-compatiblebridge or router. The PPP async-sync protocol complies withInternet Engineering Task Force (IETF) RFC 1662. The menu pathto select PPP is shown in Figure 6-23.The asynchronous control character map (ACCM) option isscanned during the negotiation. When the ACCM option is seenin a configure ACK link control packet, it is adopted by the ISU2x64. In addition, when the ACCM option is not seen in the con-figure-request packet from the network, the ISU 2x64 will add itto the packet.Figure 6-23PPP Menu Tree3=CONFIG1=Netw. options2=DTE options3=Protocol4=Quick setup5=Security6=Remote Config1=Clear Channel2=BONDING mode 13=V.1204=V.1105=DSU 57.6 ASYNC6=T-LINK7=SAP8=FALLBACK9=PPP async-sync 1=PPP2=Multilink PPP3=PPP w/Comp
