Re: Help explaining the (apparent) extra index seen in atPhysAddress?

On Wed, Apr 8, 2009 at 5:34 PM, Dave Shield <[email protected]>wrote:

> 2009/4/8 Fulko Hew <[email protected]>:
> > RFC1213-MIB::atPhysAddress.2.1.10.23.0.1 = Hex-STRING: 00 13 C3 9A 0E E0
> >
> > Decoding the response I see 3 (?) elements of indexing:
>
> No - that table has two indexes - atIfIndex and atNetAddress
> (See the RFC1213-MIB for the definitions).
>
>
> > atPhysAddress.2.1.10.23.0.1
>
> '2' is the interface index - atIfIndex
> "1.10.23.0.1" is the atNetAddress value
>
>
> > a) I don't understand why the 'extra' element is in the indexing, and
> what
> >    is in the MIB definition for this index variable that tells me to
> expect it?
>
> "10.23.0.1" is the IP(v4) address, as you've spotted.
> the extra element is actually a consequence of how the "NetworkAddress"
> syntax type is defined.   From RFC1155
>
>       NetworkAddress ::=
>           CHOICE {
>               internet
>                   IpAddress
>           }
>
> It's actually that CHOICE that introduces the .1 subidentifier.
>

OK, thats what I thought, but, is it a '1', because:

a) only one instance of the CHOICE was being returned, or
b) because ipAddress is the first enumeration in the CHOICE?

> b) Are there any other situations where this occurs?
>
> No.
> The atTable is the only place where NetworkAddress is used.
> Note that this table is a hangover from the original MIB-I, and was
> deprecated in MIB-II (RFC1213), being effectively replaced by
> ipNetToMediaTable (which doesn't use the NetworkAddress
> type, and hence omits this .1 subidentifier).
>
> It's obsolete - don't worry about it.


That may very well be, but when I browse a system, both my OpenServer
and Linux boxes respond with content... so I have to be able to cope with
that.
(just in case)

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