Re: Query: SNMP Prococol

Thanks Dave, for a wonderful explanation

Another question struck my mind...
We know that, the SNMP agent(Server) listens on port 161 for SNMP GET/SET
requests from the SNMP Manager (Client). The SNMP Agent then sends back a
response (GET-RESPONSE) to the SNMP Manager.  This will be received by the
SNMP Manager on which Port? is it on Port 161 only?
And during the GET-RESPONSE sent from SNMP Agent to SNMP Manager--- Who is
the Server and who is the Client??Does it get reversed or remains the
same(SNMP agent as Server and SNMP Manager as Client)


On Mon, Oct 18, 2010 at 5:52 PM, Dave Shield <[email protected]>wrote:

> On 18 October 2010 12:57, Queenie de Melo <[email protected]> wrote:
> > So the SNMP agent(Server) listens on port 161 for SNMP GET/SET requests
> > from the SNMP Manager (Client)
>
> Correct.
>
> (Strictly speaking, the agent can listen on any available port,
>  but port 161 is the standard port for SNMP information retrieval)
>
>
>
> > What about in Case of traps?
> >
> > The SNMP Manager in this case listens on UDP port 162 for the Traps sent
> by
> > the SNMP Agent. So in this case, is it that the SNMP Manager is .... the
> > Server and SNMP Agent is the client??
>
> That's right.
>
> The SNMP agent (or some other application that generates traps) is the
> client
> and the application that receives the trap is the server.
>   The official terminology is "notification generator" and
> "notification receiver".
>
> The notification receiver may be the same SNMP manager application as the
> one generating information retrieval requests.   Or it may be a dedicated
> trap-receiving application (such as the Net-SNMP 'snmptrapd').
>   But the most important thing here is that the client-server relationship
> is
> reversed for traps, when compared to GET/SET requests.
>
>
>
> > Another query i had is: what exactly are SNMP INFORMS?
>
> A trap is sent from the agent to the trap receiver, but there's no
> acknowledgement sent back.   So the agent doesn't know whether
> the trap got there safely (let alone whether it was acted upon).
>
> An INFORM is essentially the same as a trap, except that it *does*
> trigger an acknowledgement.   So the agent (or other notification
> generator application) knows that the inform was received.
>   (Whether the receiver actually did anything with it is a different
> question!)
>
> Think of this as the same as "read receipt messages" in the context of
> email.
>
>
>
>
> >> SNMP inform is nothing it's an acknowledgment mechanisim in SNMP. which
> is
> >> getting supported from snmpv2c and snmpv3 onwards
> >
> > Is it sent from the Manager to the Agent in response to a TRAP?
>
> No
>
> >
>  or is it
> > sent from Agent to Manager just like a trap (but u want manager to ack
> the
> > receiptof trap)
>
> Yes.
>
>
>
> >    or is it sent from NMS(SNMP Manager) to another SNMP Manager
> > ????
>
> "SNMP Manager" is something of a vague term.
> Any SNMP application can act in various different roles - hence the
> current specifications talk in terms of "notification receiver" or
> "notification generator"  (and similarly for GET/SET requests)
>
> It's perfectly possible for one SNMP manager application to signal
> to another, using traps or informs.   But the most typical use of traps
> or informs would be from an agent to an NMS.
>
> Dave
>

------------------------------------------------------------------------------
Download new Adobe(R) Flash(R) Builder(TM) 4
The new Adobe(R) Flex(R) 4 and Flash(R) Builder(TM) 4 (formerly 
Flex(R) Builder(TM)) enable the development of rich applications that run
across multiple browsers and platforms. Download your free trials today!
http://p.sf.net/sfu/adobe-dev2dev

_______________________________________________
Net-snmp-users mailing list
[email protected]
Please see the following page to unsubscribe or change other options:
https://lists.sourceforge.net/lists/listinfo/net-snmp-users