Re: 56k on PM from Alex Henthorn

Alex (alex@livingston.com)
Wed, 30 Oct 1996 16:11:17 -0800

At 06:24 PM 10/30/96 -0500, you wrote:
>So if I understand this correctly, any PM Communications Server can be
>used as a multiport router with ports set for hard-wired operation at
>57,600 kbps connected to the Adtran DSU 5600 as an asynchronous DTE using
>RTS CTS handshaking, thence being converted to synchronous transmission
>across a telco 56/64 kbps DDS/ADN to any CSU/DSU with matching
>characteristics for a head end cost of about $400 per dedicated line.

Thats how I understand it. Remember, the async ports are rated for
115.2Kbps--and are tested to support 30 hardwired connections. Just don't
try hooking all 30 ports this way, hard wired, on a PM2ER--the sync port
will be draggy, due to DMA (sync) vs. Interrupt controlled (async) CPU access.

>Overhead would consist of asynchronous start and stop bits (80%) and
>synchronous framing recognizing that the data will not arrive at the
>receiver contiguously. This apparantly results in an observed rate at
>about 75% of the 56k theoretical value.

Sounds about right to me.

Please correct me, anyone, if this sounds wrong.

alex
Alex Henthorn Livingston Enterprises
Senior Technical Product Manager 6920 Koll Center Parkway #220
Product Marketing Engineer Pleasanton, CA 94566
alex@livingston.com Voice 510-485-6787 Fax 510-244-1903