Subject: PPP

From: "Bill Cunningham" <[email-masked]>
Date: Thu, 28 Feb 2002 06:55:08 -0500

In what layer is PPP in the TCP/IP suite?

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From: Paul Day <[email-masked]>
Date: Thu, 28 Feb 2002 20:24:52 +0800 (WST)

> In what layer is PPP in the TCP/IP suite?

The top of Layer 1 - it's part of the "Network Interface" layer of the
TCP/IP conceptual model.

PD

-- 
Paul Day     Web: www.bur.st/~bonfire

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From: Lloyd Wood <[email-masked]>
Date: Thu, 28 Feb 2002 16:38:24 +0000 (GMT)

> In what layer is PPP in the TCP/IP suite?

It's _everywhere_.

What started out as a roughly HDLC-equivalent framing encap for IP
with a checksum, intended for point-to-point links, has become deeply
embedded in network stacks for e.g. mobile operators, tied in with
AAA... anything PPP over L2TP (over UDP) over IP...

As the protocol that can tunnel everything (not just IP) over
everything, PPP forms the new waists in the overblown multi-tiered
hourglasses. PPP is the ubiquitous encapsulation that mpls or AAL5
always wanted to be.

L.

is waiting for someone to notice that ubiquitous PPP means that
multicast is doomed. Oh, and PPPoE dooms broadcast, too.

<[email-masked]>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>

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From: Matt Crawford <[email-masked]>
Date: Thu, 28 Feb 2002 11:20:44 -0600

> <DIV><FONT face=3DArial size=3D2>In what layer is PPP in the TCP/IP=
> =20suite?</FONT></DIV></BODY></HTML>

Layer 2.71828

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From: Brian Lloyd <[email-masked]>
Date: Thu, 28 Feb 2002 08:52:49 -0800

>In what layer is PPP in the TCP/IP suite?

I have read some of the other responses and it reinforces my belief that 
most people don't understand PPP's relationship to IP and either the 
5-layer (internet) or 7-layer (ISO) models.

PPP is really both the link and lower network layers. (The ISORMites 
discovered that layer three was really several layers in itself but found 
it difficult to say that the 7-layer model was really a 9-layer model so 
they created sublayers, i.e. layers 3A, 3B, and 3C.  Something about 
Padlipsky comes to mind here.) The best way to think of PPP is a degenerate 
network of two nodes, not a link between two devices.  If you think of it 
in this way, things like multilink and L2TP begin to make some sense.  The 
problem occurs when people forget this.

The way that I think of it is that the LCP negotiation represents 
configuration of the link layer while the NCP negotiation configuration at 
the network layer.

And I continue to kick myself for allowing negotiation of multilink as part 
of LCP instead of doing it after authentication.  I fear that this helped 
screw up L2TP too.  I admit I caved to people who were worried about how 
long it took PPP to complete negotiation, something that just isn't very 
important.

Brian Lloyd
[email-masked]
+1.530.676.1113 - voice
+1.360.838.9669 - fax

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From: Frank Solensky <[email-masked]>
Date: 28 Feb 2002 16:20:56 -0500

> > =20suite?</FONT></DIV></BODY></HTML>

I should have exp()ected that..

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From: Brian Lloyd <[email-masked]>
Date: Thu, 28 Feb 2002 10:32:34 -0800

>hourglasses. PPP is the ubiquitous encapsulation that mpls or AAL5

When all you have is a hammer, everything looks like a nail.

>multicast is doomed. Oh, and PPPoE dooms broadcast, too.

It is ugly, isn't it.  But in a world where it is much easier to 
authenticate and account for a circuit instead of a bunch of random 
datagrams, are you surprised?

I must admit, we all laughed when Karl Fox indicated that he had 
implemented PPP over TELNET back in 1993 or so.  We thought it a hilarious 
joke.  I guess my blood should have run cold back then.

And to think that, the reason for PPP was a response to the limitations 
of  SLIP and, oh by the way, we can use it to encapsulate IP over T1 lines 
between dissimilar routers.

Brian Lloyd
[email-masked]
+1.530.676.1113 - voice
+1.360.838.9669 - fax

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From: "John Buda" <[email-masked]>
Date: Thu, 28 Feb 2002 21:54:07 -0500

I think Matt really meant PiPiPi

which is layer 3.1415926535897932384626433832795(and just keeps on going)

John Buda

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of Matt
Crawford
Sent: Thursday, February 28, 2002 12:21 PM
To: Bill Cunningham
Cc: [email-masked]
Subject: Re: PPP

Layer 2.71828