BPX SNMP Agent 14-5
MIB II Support
Responses to Set Requests
When an SNMP manager workstation sends an SNMP Set request packet to a BPX agent, it utilizes
the IP protocol for addressing. The request packet can use either a LAN interface for a locally
attached management workstation or a network interface for remote access. Each packet has the
ASN.1 format, which is suitable for transmission via the UDP protocol. Once it arrives, the packet
is decoded to a Protocol Data Unit (PDU). This PDU is the SNMP internal packet structure.
Each variable in the varbind list is located, checked for visibility in the current MIB view, checked
for write-access, and type-matched against the set request. A user-defined function is then called to
validate the Set PDU. This validation mainly determines if the Set request packet follows the
guidelines defined for the BPX switch. This function returns either good status or an error. The error
indicates the PDU is bad and should be rejected. Processing continues with tests for accessibility and
acceptability.
Each variable in the varbind list is tested for accessibility and acceptability. User-defined test
functions associated with each variable are called to implement the tests. A failed test returns a
specifier for the variable and a reason code. Any failed test results in a failed Set request. Upon
successfully passing the test functions, the set request can proceed to set the requested variables on
the specified switch. The SNMP agent calls a user-specified set function to implement the
modifications.
Upon either a successful completion or an error, the Set request PDU is modified to become the
response PDU. The response PDU also contains the values of the variables in the original Set
request. This PDU is encoded into ASN.1 format and inserted into the response packet. The Set
response packet goes to the workstation that generated the request.
MIB II Support
The BPX SNMP agent supports the following groups in the Internet SNMP MIB II:
• ARP
• ICMP
• Interfaces
• IP
• SNMP
• System
• TCP
• UDP
