[comp.protocols.tcp-ip] SNMP UDP port

crm413c@bcars19.bnr.ca (Peter Ng) (04/25/91)

Hi,

  We have questions regarding the UDP port number used
in the SNMP message.

  In the RFC 1157 section 4 "Protocol Specification", it
states "A protocol entity receives messages at UDP port
161 on the host ....".

Here are the questions:

(1) Does the statement implies that a Network management
    station must receive SNMP message (other than traps)
    on UDP port 161?
   (1.1) If (1) is yes, then NMS and the agent cannot
         both reside on the hosts (e.g.workstation)?

(2) Is it a protocol violation to receive messages on any
    other UDP ports (other than traps on 162)?

(3) In practice, could we assign any unreserved port to
    the source port of the outgoing get_request message
    (with destination port 161)?  Should we expect to receive
    a get_response on the same port that we assigned to
    the outgoing get_request? In this case is the statement
    quoted from RFC 1157 violated?

Thanks in Advance

rpc@hpcndaw.CND.HP.COM (Ron Poppen-Chambers) (04/29/91)

> 
>   In the RFC 1157 section 4 "Protocol Specification", it
> states "A protocol entity receives messages at UDP port
> 161 on the host ....".
> 
> Here are the questions:
> 
> (1) Does the statement implies that a Network management
>     station must receive SNMP message (other than traps)
>     on UDP port 161?
>    (1.1) If (1) is yes, then NMS and the agent cannot
>          both reside on the hosts (e.g.workstation)?
> 

No to (1). The management station should only receive traps and responses
to requests. This can be done on a port other than 161.

> (2) Is it a protocol violation to receive messages on any
>     other UDP ports (other than traps on 162)?

I believe that an object manager/agent would be in violation if it did this.


> (3) In practice, could we assign any unreserved port to
>     the source port of the outgoing get_request message
>     (with destination port 161)?  Should we expect to receive
>     a get_response on the same port that we assigned to
>     the outgoing get_request? In this case is the statement
>     quoted from RFC 1157 violated?

I believe this is the prefered method. The response should be sent to the
port that sent the request, but I don't believe that this is explictly 
stated in the RFC.


-----------------

Ron Poppen-Chambers
rpc@hpcnd.cnd.hp.com