Farallon Communications 612 用户手册

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页码 162
5-10
Netopia ISDN Modem User’s Guide
B Channels 
The B Channels area lets you select options for your two ISDN 
B channels.
Data Rate. Choose the B-channel data rate you want from the Data 
Rate pop-up menu. The data rate options are 56 Kbps and 64 Kbps 
(the two data rates ISDN suppor ts). Not all telephone ser vices 
suppor t the 64 Kbps data rate. Select the data rate used by your 
telephone company.
Protocol. The Protocol pop-up menu lets you choose the transpor t 
protocol you want. The protocol options are QuickSelect, 
Async/Sync PPP Conver t, and V.120. In most cases, you should use 
the QuickSelect protocol. QuickSelect allows the Netopia ISDN 
Modem to automatically detect the protocol in use on the ISDN line 
and adapt to that protocol. Also, when QuickSelect is active, the 
modem conver ts asynchronous Point-to-Point (PPP) information into 
synchronous (HDLC-based) PPP information. If you select either the 
Async/Sync PPP Conver t or V.120 protocol, the Netopia ISDN 
Modem will only use the selected protocol.
Enable Compression. (This option is only available for the Netopia 
ISDN Modem Model 412.) Check the Enable Compression box to 
turn on data compression. Data compression is a method of 
reducing the size of data without losing any of the information. 
Models 412 and 612 of the Netopia ISDN Modem automatically use 
Stac data compression to compress data to improve data transfer 
times. To take advantage of data compression, the device you are 
dialing into must also suppor t data compression. Note that the 
Netopia ISDN Modem’s data compression will not be used if data 
compression is in use in your communications application. For more 
information about data compression, 
V.120 Max Frame Size. The V.120 Max Frame Size pop-up menu 
lets you specify the maximum number of bytes in a V.120 frame. 
V.120 is an alternative transpor t protocol to PPP. The available 
frame sizes range from 240 to 256 bytes. Leave this set at 256 
unless your system administrator or Internet Ser vice Provider (ISP) 
instructs you to specify a different value.