Subject: Problem/question with the Tunnel MIB

From: "Peder Chr. Norgaard" <[email-masked]>
Date: Tue, 1 Jun 1999 19:57:29 +0200 (MET DST)

I have a problem understanding section 4.1.1, the layering model, of the
tunnel mib, draft-ietf-ifmib-tunnel-mib-03.txt.   So this is plea for
either clarification or modification.

I do not understand how a tunnel can be associated with a physical
interface.  The element that associates a tunnel with the rest of the
interface graph is the local IPv4 address.  And only in one specific case
(that of the Ethernet) is a local IPv4 address associated directly with a
physical interface.  In all other cases there are two or more intervening
layers.  (In the ATM case it is even more funny, with the switch fabric
isolating the SAR part of the interface graph from the line part).

I would suggest that the wording is changed to specify that the tunnel
interface indices are correlated using the ifStack directly with "those
interfaces on which the local IPv4 addresses of the tunnels are
configured".

(Of course, the current text could be interpreted that way; it does not
say "correlated *directly* to the physical interfaces".  But in that case
the text's emphasis on "physical interfaces" is misleading.)

Strictly spoken, a direct correlation to the address-carrying interfaces
would be redundant, as it could be derived by a manager application
combining the IF-MIB and tunnel MIB.  On the other hand, it does not hurt.

Otherwise, it seems like a very useful MIB. It is nice for once to see a
proposal for a standard MIB that makes a go at being useful for
configuration.

best regards

--
Peder Chr. Nørgaard                   System Developer, M. Sc.
Telebit Communications A/S            tel: +45 86 28 81 77 - 49
Fabrikvej 11                          fax: +45 86 28 81 86
DK-8260 Viby J   Denmark              e-mail: [email-masked]

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From: Dave Thaler <[email-masked]>
Date: Thu, 3 Jun 1999 12:54:34 -0700 (PDT)

> either clarification or modification.
[...]
> interfaces on which the local IPv4 addresses of the tunnels are

Peder, your wording suggestion sounds fine to me.

-Dave