Re: Multiple entities - snmpv3

David Spakes <[email protected]>
Newsgroups gmane.ietf.snmpv3
Message-ID <[email protected]>
On Fri, 25 Oct 2002, Tom Petch wrote:

> That to me is why I need multiple contexts (although I have never
> heard if that is why the SNMPv3 architects specified them:-).


Hi Tom,

Context (specifically, contextName) was architected specifically for the
type of scenario you describe--i.e., "a separate MIB II for each hub or
router or switch instance"--otherwise known as a virtual agent.

Context is really just a formalization of a common practice in SNMPv1 of
overloading the community string.  Community strings were specifically
intended for authentication.  But developers found it useful to associate
communities with virtual agents/instances of a device in a box.  So if you
do a mibwalk using community string "public1", you get back different
object values than if you use community string "public2".


> The bad news is that all the boxes I see are SNMPv1; and I am not
> holding my breath.
> 
> I only have
> one backplane, one physical lump, one management module (plus backup),
> one set of console ports so I want to have one SNMP engine, one set of
> security and access/transport information that supports multiple MIB
> module instances


If you are running IP over your backplane, and if at least one of your
blades has enough horsepower to run multiple processes (for example, if
you are running an embedded Linux on the board), then it is pretty easy
to fold together individual SNMPv1 agents in the box under a single SNMPv3
umbrella and to give each of the agents its own contextName.  See the
white paper called "Proxy Agent Concepts" on our web site at
http://www.snmp.com/protocol/proxyinfo.html.  You would be most interested
in Section 1.3.1 on "Native Agent Adapter".

Regards,

David Spakes


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