[c-nsp] ios-xr asr9k ipv6IfAdminStatus does return next instance if it does not exist

Florian Lohoff f at zz.de
Mon Dec 22 14:33:38 EST 2014

On Tue, Dec 16, 2014 at 10:28:26AM +0100, Florian Lohoff wrote:
> After digging into this a bit more
> On Tue, Dec 16, 2014 at 05:40:43AM +0100, Florian Lohoff wrote:
> > 
> > Hi,
> > did anyone see something like this?
> > 
> > 	$ snmpget -c public -v 2c asr9k-corerouter ipv6IfAdminStatus.77
> > 	IPV6-MIB::ipv6IfAdminStatus.79 = INTEGER: up(1)
> > 
> > Asking for instance .77 and get .79.
> It seems this is a clear violation of the SNMPv2 RFC 1905
>     RFC1905 4.2.1. The GetRequest-PDU
>     [ ... ]
>     (1)  If the variable binding's name exactly matches the name of a
>          variable accessible by this request, then the variable binding's
>          value field is set to the value of the named variable.
>     (2)  Otherwise, if the variable binding's name does not have an OBJECT
>          IDENTIFIER prefix which exactly matches the OBJECT IDENTIFIER
>          prefix of any (potential) variable accessible by this request, then
>          its value field is set to `noSuchObject'.
>     (3)  Otherwise, the variable binding's value field is set to
>          `noSuchInstance'.
> So it should return with `noSuchInstance' not some other random interfaces
> IPv6 status.

Response from my TAC case: Cisco thinks not returning an exact match
by replying with the next instance for a GetRequest-PDU is valid behaviour.

I read the above VERY different - If (1) does not apply (as it doesnt
when asking for a non existant instance) you either are allowed
to return noSuchObject or noSuchInstance. 

There is no way i can see RFC1905 allows returning something else than
an exact match on a GetRequest-PDU.

The question i responded is that why the IF-MIB and the IPV6-MIB behave
differently and that i think its only ever valid to return a non exact
match when using GetNextRequest-PDU.

I am little bit angry by the so obviously wrong answer.

Florian Lohoff                                                 f at zz.de
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