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Re: [lwip-users] Interfacing LwIP for a radio communication

From: Sylvain Rochet
Subject: Re: [lwip-users] Interfacing LwIP for a radio communication
Date: Wed, 4 Feb 2015 22:31:30 +0100
User-agent: Mutt/1.5.21 (2010-09-15)

Hello Sergio,

On Wed, Feb 04, 2015 at 05:53:52PM -0300, Sergio R. Caprile wrote:
> Something is not clear to me here...
> "PPPoS" might be confused with PPP over SONET/SDH
> You guys are talking about plain old PPP, RFC-1661, Point-to-Point
> Protocol, 

Exactly, I known it's a little bit confusing, we are using PPPoS on lwIP 
as a meaning for PPPoSerial, you are right PPPoS is oftenly used for 
PPPoSONET elsewhere.

> which (by definition) works over any point-to-point link, as long as 
> it is full-duplex and can carry bytes (octets).

Full-duplex or half-duplex actually, radio links are mostly working in 
half-duplex condition.

> I guess "point-to-point" and "peer-to-peer" can be considered 
> equivalent in this aspect. So... Please forgive my ignorance, I don't 
> know what a SwMi is (even less a centralized one) ;^) PPP runs on 
> telephone modems and serial ports, although, as Sylvain cleverly 
> points out, SLIP will have way less overhead, both in bandwidth and 
> code size.
> Perhaps confusion comes from the way cell modems capture 
> PPP by "dialing" a fake number ? Or because of authentication with 
> PAP/CHAP ? As long as the two end points can see each other, you can 
> establish a PPP link or a SLIP link. You don't need to "dial" or 
> "login" to have PPP working. Authentication is not mandatory, you can 
> bypass it.

Indeed !, thanks for pointing that out, this is obvious for me but I 
guess this isn't actually obvious at first sight on PPP.


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