Subject: Re: IPCP Option Required?

From: [email-masked]
Date: Fri, 12 Jan 2001 15:59:30 -0500

There are some DSL providers giving static IP addresses.
If they use PPPoE to negotiate a session, and authentication determines
a user, probably IPCP IP-Address could be avoided.
But in this case the client and server have (though ppp does
not have a client-server relationship, PPPoE has a client-server
relationship, so I just use that way), apriori has an understanding of
a common IP address.

Maybe this be could a valid scenario of not using IPCP-IP address option
or even if a static address is used, are the peers expected to negotiate it
?

Thanks
Naga

James Carlson <[email-masked]>@merit.edu on 01/12/2001 02:43:53 PM

Sent by:  [email-masked]

To:   "Michael Koller" <[email-masked]>
cc:   [email-masked]
Subject:  Re: IPCP Option Required?

There are folks doing things with Mobile IP (see IS-835) where the
IPCP IP-Address option isn't used, but in general I think you need a
*really* compelling reason before you decide not to implement it.
(And I'm not sure I believe the aforementioned folks are necessarily
correct.)

---

From: James Carlson <[email-masked]>
Date: Fri, 12 Jan 2001 16:09:52 -0500 (EST)

> There are some DSL providers giving static IP addresses.

OK.

> a user, probably IPCP IP-Address could be avoided.

Why should it be?  If it is avoided, then you are requiring that user
to statically configure his IP address, and you're not checking for
errors.  Is that a good thing?  Are the DSL customers all savvy enough
to do this right every time?

> relationship, so I just use that way), apriori has an understanding of

Yes, as I said before, that's how things were done in the past with
SLIP.  That isn't a good thing.

> or even if a static address is used, are the peers expected to negotiate it

I would strongly recommend that the peers still negotiate the endpoint
addresses using the IPCP IP-Address option, even if the addresses are
well known.  And even if the addresses are configured on both ends of
the link.

The intent of the IPCP IP-Address option is *not* to assign addresses,
though that's certainly the way it's commonly used.  The intent is to
avoid the kinds of broken configurations (and horrible text-based
kludges) that were once common with SLIP.

If you want to avoid IPCP IP-Address, you really should have a
*compelling* need to do so.  The only one I can think of is that you
simply do not have access to any address because you're doing some
kind of funky bridging.  (Even then, I'd strongly recommend sending
IPCP IP-Address with 0.0.0.0 just to see if the peer knows your
address and will be so polite as to inform you.)

-- 
James Carlson                                  <[email-masked]>
"PPP Design and Debugging" --- http://people.ne.mediaone.net/carlson/ppp