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Re: [oc] help!!

Aloha!

mayank digvijay bindal wrote:
> i want implement the PPP(point to point protocol)using HDL & FPGA.i know 
> its a stack of protocol,so i  want to implement some protocols of it 
> only.someone know how to approach for this problem.
> thank u 4 giving response

I don't want to come off as a negative or anything, but I have a hard time to 
see what are to be gained by implementing PPP in HW. Unless of course it's a 
school/academic or recreational activity.

PPP is basically just a giant hairball of a FSM with tons of states, events 
and trasitions. There are few things in the control machine that can be gained 
by moving to HW and little parallelism to be extracted.

Whet I see that you can do in terms of HW-support are:
(1) Frame reception. and decoding. A buffer that receives the incoming packet 
(containing the PPP traffic), extract fields and pointers to where fields and 
data are in the buffer.

(2) Predecoding of commands. Like most IETF-protocols, PPP uses ASCII-strings 
for command and response communication. Create a preprosseor/parser that 
handle these commands so that the FSM simply can check a HEX value.

(3) Postprocessing. Pack stuff for transission and handle signalling towards 
MAC layer.

(4) Magic number calculation and detection. PPP uses a magic number for 
detection of loopback, collisions etc. The actual calculation, checking can be 
supported in HW leaving the decision of what to do for the control machine.

But, of course, for curiosity, entertainment purposes, experimenting with 
state encodings, switching activity analysis etc, implementing PPP might very 
well be a fun thing to do.


For more info, check out RFC 1661:
http://www.ietf.org/rfc/rfc1661.txt

Good luck!
-- 
Med vänlig hälsning, Yours

Joachim Strömbergson - Alltid i harmonisk svängning.
VP, Research & Development
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