| 摘要 |
PURPOSE: A network interface apparatus of the remote access system is provided to interface the frame relay network and the ISDN network by an identical hardware in the remote access system to connect a network and a network. CONSTITUTION: A line interface and framer unit(221) interfaces networks by an E1 link. A PLL(222), synchronized with a clock received from the line interface and framer unit(221), provides a system clock. A time switch(223) separates a D channel from an E1 frame, outputs it to a main processor(225) and divides the data channels of 30 channels in case of interfacing with an ISDN network. In case of interfacing with a frame relay network, the time switch(223) provides 31 channels without separating the D channel. An HDLC processing unit(224) processes the 30 channels from the time switch into a channelized HDLC protocol in case of interfacing with the ISDN network and, in case of interfacing with the frame relay network, processes the 31 channels into an unchannelized HDLC protocol. The main processor(225) carries out a required signaling procedure, receiving the D channel data from the time switch(223). |
