BPX SNMP Agent 14-3
SNMP Functions
SNMP Functions
The SNMP protocol provides a basic query-response model for network management. The network
manager has access to Get (Get-Next) and Set functions.
A Get request lets the manager read variables in the BPX switch. The request consists of a single
variable or a list of variables. The BPX database subsequently returns the requested values.
The Get-Next request lets the manager obtain the successor to the given variable’s object identifier.
The returned object identifier can serve as input to another Get-Next request so the manager can
lexicographically walk through the MIB.
A Set request lets the manager modify variables in the BPX switch. The request consists of either a
single variable or a list of variables. The values supplied in the request modify the BPX database.
The variables and their associated values in the request message are put into a response message and
returned to the requesting management workstation. The format of the Set response message is the
same as that of the Get response message.
SNMP requests from the manager have the same access level as non-privileged users.
Non-privileged access can be read-only, read-write, or no access. To maintain access control, each
Get and Set request is checked for the correct community string. The community string determines
the access privileges that a management workstation has. A separate community string exists for Get
requests and Set requests.
The node initializes the community strings to no access, so the user must set the strings to the
appropriate values. The community strings can be set and displayed by the cnfsnmp and dspsnmp
super-user commands, respectively (see the Cisco WAN Switching Super-User Command Reference
publication for details).
Responses to Get, Get-Next, and Set requests are returned in a response packet along with a status
field. The status field can be one of the following:
If an error occurs, the appropriate error code is encoded in ASN.1 format and inserted into the
response packet.
Note In the sections that follow, user-specified command names are in lower case.
• noError (0) Successful operation.
• tooBig (1) The agent could not fit the results of an operation into a single SNMP
message.
• noSuchName (2) The requested operation identified an unknown variable when attempting
to modify a variable.
• badValue (3) Requested operation specified an incorrect syntax or value when
attempting to modify a variable.
• readOnly (4) Requested operation attempted to modify a variable that, according to
the community profile, may not be written. (No longer supported by
Standards.)
• genErr (5) All other failure responses.
