使用一个SNMP代理监视同一设备的多个实例

Question

I have equipment that is non SNMP-enabled . I have the API to get its status and am implementing an SNMP agent for it. I did that with SNMP4j and can answer GET requests and send traps.

The problem I have is that there are several (2) such equipments to monitor with the same instance of my program. So far, I added a branch for each equipment in the MIB like 1.3.6.1.4.1.PEN.devices.1.xxx and 1.3.6.1.4.1.PEN.devices.2.xxx but 1-that's ugly and 2-I can't give a MIB usable for each equipment but a single MIB for the whole System with redundant information and that's also ugly ;)

I'm not sure if the MIB Table object is suitable for that, but it doesn't sound like the way to go (I have a fixed number of equipment). I also saw that RFC 3413 §3.5 describes SNMP proxy forwarder but I'm not sure it is what I need to implement (my equipments are not SNMP-enabled), and SNMP4j ProxyForwarder seems to map a MIB to another MIB.

With SNMP4j, I implemented the processPDU() method of the CommandResponder interface and I was hoping that, if the Supervision software is configured to use my program as a "proxy forwarder", there could be some information available in the CommandResponderEvent for me to send the correct response PDU (though I didn't find any such thing, I might have missed something).

I could start several instances of my agent (one per equipment) but I'd rather not for sparse ressources reasons. What would be the best way to tackle that problem? Table? Proxy? Other? Not possible?

EDIT:

I have found that some NNM add an extra Variable Binding in the GET request to indicate which equipment to address (SNMP-proxy-like), while some other map the equipment by changing the community in the GET. Are these viable options? Which one is the most common/acceptable?

Answer 1

Using a simple table here to show general concepts of tables and rows ...

This is how to retrieve a example table (with an index and 2 more columns). Perhaps each of your equipments would be a row in your own table (with a bunch of data in your own columns)

snmptable  -M +.  -m +ALL -v 2c -c public  -Ci  myhost   SNMPv2-MIB::sysORTable
SNMP table: SNMPv2-MIB::sysORTable

 index                                        sysORID                                              sysORDescr  sysORUpTime
     1          SNMP-MPD-MIB::snmpMPDMIBObjects.3.1.1         The MIB for Message Processing and Dispatching. 0:0:00:00.33
     2       SNMP-USER-BASED-SM-MIB::usmMIBCompliance         The MIB for Message Processing and Dispatching. 0:0:00:00.33

Walk that table :

snmpwalk   -M +.  -m +ALL -v 2c -c public  myhost  SNMPv2-MIB::sysORTable
SNMPv2-MIB::sysORID.1 = OID: SNMP-MPD-MIB::snmpMPDMIBObjects.3.1.1
SNMPv2-MIB::sysORID.2 = OID: SNMP-USER-BASED-SM-MIB::usmMIBCompliance
SNMPv2-MIB::sysORDescr.1 = STRING: The MIB for Message Processing and Dispatching.
SNMPv2-MIB::sysORDescr.2 = STRING: The MIB for Message Processing and Dispatching.
SNMPv2-MIB::sysORUpTime.1 = Timeticks: (33) 0:00:00.33
SNMPv2-MIB::sysORUpTime.2 = Timeticks: (33) 0:00:00.33 

Access one part of above by walk :

snmpwalk   -M +.  -m +ALL -v 2c -c public  myhost  SNMPv2-MIB::sysORDescr.2
SNMPv2-MIB::sysORDescr.2 = STRING: The MIB module for SNMPv2 entities

Access one part of above by GET :

snmpget   -M +.  -m +ALL -v 2c -c public  myhost  SNMPv2-MIB::sysORDescr.2
SNMPv2-MIB::sysORDescr.2 = STRING: The MIB module for SNMPv2 entities

EDIT: To see how this OID fits into the tree look at ...

snmptranslate -M+. -m +ALL    1.3.6.1.2.1.1
SNMPv2-MIB::system
snmptranslate -M+. -m +ALL    1.3.6.1.2.1.1.9
SNMPv2-MIB::sysORTable
snmptranslate -M+. -m +ALL    1.3.6.1.2.1.1.9.1
SNMPv2-MIB::sysOREntry
snmptranslate -M+. -m +ALL    1.3.6.1.2.1.1.9.1.3
SNMPv2-MIB::sysORDescr
snmptranslate -M+. -m +ALL    1.3.6.1.2.1.1.9.1.3.2
SNMPv2-MIB::sysORDescr.2