Configuration Guide    SNMP Configuration 
SNMP Versions 
This software supports these SNMP versions: 
  SNMPv1:  The  first  formal  version  of  the  Simple  Network  Management 
Protocol, which is defined in RFC1157. 
  SNMPv2C: Community-based Administrative Framework for SNMPv2, an 
experimental Internet protocol defined in RFC1901. 
  SNMPv3:  Offers  the  following  security  features  by  authenticating  and 
encrypting packets: 
1.  Ensure that the data are not tampered during transmission. 
2.  Ensure that the data come from a valid data source. 
3.  Encrypt packets to ensure the data confidentiality. 
Both the SNMPv1 and SNMPv2C use a community-based security framework. 
They  restrict  administrator’s  operations  on  the  MIB  by  defining  the  host  IP 
addresses and community string. 
With the  GetBulk  retrieval  mechanism,  SNMPv2C sends  more  detailed  error 
information type to the management station. GetBulk allows you to obtain all the 
information or a great volume of data from the table at a time, and thus reducing 
the  times  of  request  and  response.  Moverover,  SNMPv2C  improves  the 
capability  of  handing  errors,  including  expanding  error  codes  to  distinguish 
different kinds of errors, which are represented by one error code in SNMPv1. 
Now, error types can be distinguished by error codes. Since there may be the 
management  workstations  supporting  SNMPv1  and  SNMPv2C  in  a  network, 
the  SNMP  agent  must  be  able  to  recognize  both  SNMPv1  and  SNMPv2C 
messages, and return the corresponding version of messages. 
SNMP Management Operations 
For the information exchange between the NMS and the SNMP Agent, six types 
of operations are defined: 
1.  Get-request:  The  NMS  gets  one  or  more  parameter  values  from  the 
SNMP Agent. 
2.  Get-next-request: The NMS gets the next parameter value of one or more 
parameters from the SNMP Agent. 
3.  Get-bulk:  The  NMS  gets  a  bulk  of  parameter  values  from  the  SNMP 
Agent. 
4.  Set-request: The NMS sets one or more parameter values for the SNMP 
Agent. 
5.  Get-response: The SNMP Agent returns one or more parameter values, 
the response of the SNMP Agent to any of the above 3 operations of the 
NMS.