Re: [Isms] IsmsQuestions on TLSTM/TSM and RFC 5343

----- Original Message ----- 
From: "Frank Fock" <fock@agentpp.com>
To: "Wes Hardaker" <wjhns1@hardakers.net>
Cc: <isms@ietf.org>
Sent: Sunday, January 23, 2011 6:24 PM

> Hi Wes,
> 
> Thanks for your reply (and also those of Tom
> and Juergen).
> 
> I understand that RFC 5343 solves the
> contextEngineID discovery problem, but
> within the last 10 years with SNMPv3
> I learned, that most SNMPv3 users do not
> understand the authoritative and context engine
> ID concepts.
> 
> There are also a couple of companies
> creating SNMPv3 devices with identical
> authoritative engine ID for all instances
> of their device. We API developers are then
> asked to work around these problems :-(

That surprises me (and sounds like a potential disaster).

To quote RFC3411
" Within an administrative domain, an snmpEngineID is the unique and
   unambiguous identifier of an SNMP engine.  Since there is a one-to-
   one association between SNMP engines and SNMP entities, it also
   uniquely and unambiguously identifies the SNMP entity within that
   administrative domain.  Note that it is possible for SNMP entities in
   different administrative domains to have the same value for
   snmpEngineID.  Federation of administrative domains may necessitate
   assignment of new values."

which seems clear, unless the concept of an engine is unclear.

On the other hand, it is much easier to burn the same identifier into
everything, rather than using a MAC address type approach and
make each device unique. Perhaps we ask too much of those making
devices.

Tom Petch

> 
> That's why I thought about simplifying
> the SNMPv3 and making the discovery of
> a contextEngineID unnecessary if not
> required by the command generator.
> 
> Nevertheless, I agree that using a single
> magic contextEngineID for the local context,
> would interfere with proxy applications,
> for example.
> 
> I will now first finish my implementation
> and then make a complete report and analysis
> of the result. This will also include using
> contextEngineId discovery with USM.
> 
> Best regards,
> Frank
> 
> 
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