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Re: SNMP lockup
On 2009-05-09, Sergei Gavrikov <sergei.gavrikov@gmail.com> wrote:
> [snip]
>
>> What I'd like a pointer on is the interface numbering in SNMP
>> OIDs. Are the interfaces supposed to be numbered 1..N with
>> interface 0 being non-existent? Or are eCos interface numbers
>> off by one and they should really be 0,1 instead of 1,2? [I
>> tried looking through the OID/ASN.1 docs, but got lost rather
>> quickly.]
[...]
>> I looked at network traces for one customer site using, I
>> believe, HP Insight. It does read the interface attributes for
>> interfaces 1 and 2. I don't see it attempt to read attributes
>> for interface 3 (which doesn't exist). I do see it attempt to
>> read attributes for interface 0 (which also doesn't exist).
>>
>> If interface numbers are supposed to start at #0, will
>> renumbering the interfaces at this point (after product has
>> been shipping for 7 years) cause more problems that it will
>> solve?
>
> That's known SNMP "issue"
What is a known issue?
> -- ?get? might want that the OID ends in .0
>
> Example:
>
> snmpget -c public -O X -v2c bridge.local sysDescr
> SNMPv2-MIB::sysDescr = No Such Instance currently exists at this OID
>
> snmpget -c public -O X -v2c bridge.local sysDescr.0
> SNMPv2-MIB::sysDescr.0 = STRING: Foo bar baz
I'm afraid I don't understand your point.
> So, IMHO, it's better to fix the agent than to make managers
> work "properly".
I wasn't propsoing that we not fix the agent. What I was
asking was
* Which of two fixes is the "standards-correct" one:
1) Leave the interfaces numbered 1,2 and fix handling
for queries of interface <1.
2) Change the interface numbers to 0,1.
* If 2) is what the standards specify, are we still better off
with 1) to maintain some backwards-compatiblity with older
versions?
My posted fix that implements choice 1).
I misunderstanding OID sematics?
Is 1.3.6.1.2.1.2.2.1.6.0 supposed to refer to the physical
address of the first network interface?
Or is 1.3.6.1.2.1.2.2.1.6.1 the physical address of the first
interface and <...>.0 is something fundamentally different?
--
Grant
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