PPP features ?

PPP features ?

[Jean Lee]

Hello,

In order to write my own application, I would like to know where I can 
find information on the ppp stack features for linux 2.4.27. Does 
anybody know it ?

In particular, does the linux ppp stack implements the following 
protocols ? :
PAP, IPCP, IP header compression, CCP, LZS and NCP

Thank you for any help...

Jean Lee

Re: PPP features ?

[James Carlson]

Jean Lee writes:
> In order to write my own application, I would like to know where I can 
> find information on the ppp stack features for linux 2.4.27. Does 
> anybody know it ?
> 
> In particular, does the linux ppp stack implements the following 
> protocols ? :
> PAP, IPCP

Yes to both.

> IP header compression

It has VJ (RFC 1144) header compression, but nobody has worked on the
newer patent-laden ROHC things.

>, CCP

Yes.

>, LZS

No, not by default.  It's patent-encumbered.  There are patches
floating around the 'net that reportedly add this.  Use at your own
risk.

(Patents aren't like copyrights, at least in much of the world.  You
can get sued successfully even if you write the darned thing from
scratch.  You can even get sued if you happened to invent it on your
own purely by accident.  Not sure about the situation in France ...)

> and NCP

That's not really a protocol.  The "NCPs" in PPP are the network
control protocols.  One of these is IPCP, the Internet Protocol
Control Protocol, which is used to negotiate IP parameters.

Or are you asking about IPX support?  (One of the IPX-related
protocols is also called "NCP.")

-- 
James Carlson                                 <carlsonj@workingcode.com>

Re: PPP features ?

[Jean Lee]

Hello James,

Thank you very much for your answer.
For the patents in France, I think it is like what you said so I will 
forgot LZS
For the NCP protocol, I am not sure but I think that it is IPCP + IP 
header compression + software compression (LZS) + CCP because it is 
wrotten like this :

/Network Control Protocol (NCP), for the PPP protocol integration 
control in the IPv4 layer :/
    /- protocol IPC management (Internet Protocol Control)/ I think that 
there is a mistake and that he want to speek about IPCP because I don't 
know IPC.
    /- IP header compression support/
    /- software compression support (LZS) optional./
   / - Compression Control Protocol (CCP)/

Does it have a meaning ?
Is there another software compression protocol than LZS which is available ?
Where did you find all this information ?

Regards,

Jean Lee

James Carlson wrote:

>Jean Lee writes:
>  
>
>>In order to write my own application, I would like to know where I can 
>>find information on the ppp stack features for linux 2.4.27. Does 
>>anybody know it ?
>>
>>In particular, does the linux ppp stack implements the following 
>>protocols ? :
>>PAP, IPCP
>>    
>>
>
>Yes to both.
>
>  
>
>>IP header compression
>>    
>>
>
>It has VJ (RFC 1144) header compression, but nobody has worked on the
>newer patent-laden ROHC things.
>
>  
>
>>, CCP
>>    
>>
>
>Yes.
>
>  
>
>>, LZS
>>    
>>
>
>No, not by default.  It's patent-encumbered.  There are patches
>floating around the 'net that reportedly add this.  Use at your own
>risk.
>
>(Patents aren't like copyrights, at least in much of the world.  You
>can get sued successfully even if you write the darned thing from
>scratch.  You can even get sued if you happened to invent it on your
>own purely by accident.  Not sure about the situation in France ...)
>
>  
>
>>and NCP
>>    
>>
>
>That's not really a protocol.  The "NCPs" in PPP are the network
>control protocols.  One of these is IPCP, the Internet Protocol
>Control Protocol, which is used to negotiate IP parameters.
>
>Or are you asking about IPX support?  (One of the IPX-related
>protocols is also called "NCP.")
>
>  
>

Re: PPP features ?

[James Carlson]

Jean Lee writes:
> For the NCP protocol, I am not sure but I think that it is IPCP + IP 
> header compression + software compression (LZS) + CCP because it is 
> wrotten like this :

That looks like a misunderstanding.  "Network Control Protocol" in the
context of PPP is just a generic term.  It's like saying "a feature"
or "a program."  It doesn't define any particular protocol.  Requiring
support for it is just nonsense.

So, yeah, sure, pppd supports NCP.  ;-}

> /Network Control Protocol (NCP), for the PPP protocol integration 
> control in the IPv4 layer :/
>     /- protocol IPC management (Internet Protocol Control)/ I think that 
> there is a mistake and that he want to speek about IPCP because I don't 
> know IPC.

That does indeed look quite garbled.

There is no such thing as "protocol IPC management."  I don't know
what that would mean in this context.

IPCP (RFC 1332) is indeed one of the PPP NCPs, and is the one you want
if you want to run IPv4.  (If you want IPv6, you need IPV6CP, a
separate NCP, which is also supported by pppd.)

>     /- IP header compression support/
>     /- software compression support (LZS) optional./
>    / - Compression Control Protocol (CCP)/
> 
> Does it have a meaning ?
> Is there another software compression protocol than LZS which is available ?

There are *many* of them.

> Where did you find all this information ?

Which information?

If you want to know what pppd supports, looking at the code itself is
probably the best answer.  Looking at the documentation that comes
with it would likely also be productive.  You can get the source here:

	ftp://ftp.samba.org/pub/ppp/

As for the list of protocols, you can look here to find the list of
data compression (CCP) algorithms:

	http://www.iana.org/assignments/ppp-numbers

(Scroll down to "PPP CCP CONFIGURATION OPTION TYPES.")  And you can
look here to find references to the documents describing those
algorithms:

	http://www.ietf.org/rfc/rfc-index.txt

For example, LZS (commonly called "Stac") is defined here:

	http://www.ietf.org/rfc/rfc1974.txt

There's also a reasonably-available book on PPP design,
implementation, and debugging that I could recommend.

-- 
James Carlson                                 <carlsonj@workingcode.com>