Subject: Re: Interface specification in route(8)
To: None <,>
From: Ignatios Souvatzis <>
List: tech-net
Date: 02/23/1999 14:01:17
On Tue, Feb 23, 1999 at 02:19:43PM +0200, Lucio de Re wrote:
> According to Ignatios Souvatzis:
> > 
> > IP version 4 point to point links, be it PPP or SLIP, be it 4.3BSD or 4.4BSD
> > derived systems, semantically do not create a network of their own.
> > 
> Accepted, although, for example, my Novell MPR (which is admittedly 
> pretty ancient, but seems built to the most rigid standards) expects 
> the ppp link to be its own subnet - doesn't do unnumbered or any 
> approximations thereto.

The standards dont force you to waste addresses on this, with IPv4.
They just tell you how to encode the packets on the wire... 

Its just that some old networking stacks do NOT now hot to handle point to 
point links.

[Btw, for IPv6 the situation is different. But you dont ahve an address problem

> > The kernel routes by looking wether the single remote address matches, when
> > it finds an interface with the POINTTOPOINT bit on.
> > 
> Does a point-to-point link get treated exceptionally, in this respect, 


> > This is 99% of a real unnumbered interface: you can share the IP address of
> > your Ethernet as your local address.
> > 
> That really appealed to me, but then it is not clear from the 
> documentation that I need to specify a mask because 
> otherwise pppd adopts not only the Ethernet address, but also the 
> netmask (I'll SEND-PR that, if I can find a way to fix it).

I must check my old pPP setup at home... I dont remember whether I specified
that explicitly.

> Also, while I'm asking, I did ask once how to make sure that ppp0 was 
> associated with a particular tty and ppp1 with another, and suggestions 
> were made that I distractedly lost.  Is there an archive I can seek 
> these responses, has a link to mailing lists, and there you have a
link to both a searchable and a complete archive.