Cisco Systems 8600 Series manual MIB II Support, Responses to Set Requests

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:

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ARP

ICMP

Interfaces

IP

SNMP

System

TCP

UDP

BPX SNMP Agent 14-5