architecture question

[Frank Fock]

Hi Rich,

Comments on the following inline:

rich coco wrote:
> Ok...time to broadcast my ignorance...
> 
>  From what i have read, I had believed that, in the context of AgentX++,
> the Master Agent would look to an external SNMP client like an SNMP agent.
> That is, a client -- eg, "snmpget" on Linux - could be used to retrieve 
> a MIB OID value
> when the Master/subAgent are running.
> 

That's right.

> What I imagined would happen was that the Master agent would get the 
> request and
> dispatch it to the appropriate subAgent. In particualr, I thought the 
> Master Agent would be
> listening on port 161 for SNMP client requests, pass the request to the 
> subAgent using the
> AgentX protocol, marshall the response from the subAgent, and pass back 
> the standard SNMP
> response to the client.
>
That's also correct.

> I succeeded in getting a MasterAgent and a single subAgent up and 
> running and they do seem to
> be communicating with eachother (I see the 20-sec pings sent by the 
> subAgent and received by the Master).
> However, when i tried out the Linux snmpget and snmpwalk commands, 
> nothing happened.
> Finally, I looked at the Master code and saw that by default it listens 
> on port 4700 !!!
> 
That's a FAQ. It uses port 4700 because on UNIX systems
one has to have root privileges to bind port 161, which most
users do not seem to have. If we would use 161 as default,
we would get a lot of messages from users asking "my agent
is unable to start".

> This now makes me think that I do not properly understand the role of 
> the Master Agent...
> 

No reason to be in doubt about it ;-)

> Is it supposed to replace the SNMP Agent that would normally run on a 
> managed device?
Yes.
> (which generally listens on port 161 (and 162 for traps?)?
> if so, why is it listening on port 4700 by default?
> 
See above.

Best regards,
Frank