Cisco Systems 8600 Series manual Responses to Get Get-Next Requests, ATM Set Requests

SNMP Functions

Responses to Get (Get-Next) Requests

When an SNMP manager workstation sends an SNMP Get 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 is in 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.

A PDU consists of one or more variables requested by the manager. The PDU’s community string is validated for correct access permissions, then the requested variables are collected within an SNMP varbind list for processing.

For each variable in the request message, the agent calls a user-defined test function that makes sure the requested variable exists. If the test confirms the existence of the variable, the agent calls a user-defined get function to gain access to the BPX database for the specified variable. The get function is appropriate for the type of request (Get or Get-Next).

A get function can read either a single scalar value or a single column entry from the database row. The user-defined get-next function provides a way to read a table of unknown elements. The get-next function returns the lexicographically next variable in the table with respect to the next variable. This mechanism lets the manager sequentially retrieve the entire table.

The test and get functions result in a Get response packet. If an error occurs, the appropriate error code is encoded in ASN.1 format and placed in the packet. If no errors occur, the returned values are encoded and placed in the response packet. The response packet goes to the workstation that originated the Get request.

ATM Set Requests

SNMP Set requests support the ATM functions in the following list. Refer to the Cisco WAN Switching Command Reference for command descriptions.

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Add ATM connection (addcon)

Delete ATM connection (delcon)

Up ATM connection (upcon)

Down ATM connection (dncon)

Modify ATM connection (cnfrcon, cnfcos, cnfpref, cnfrcon)

Test ATM connections (tstcon, tstdelay)

SNMP Set requests can implement the following BPX commands on ATM ports:

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Up ATM port (upfrport)

Down ATM port (dnfrport)

Modify ATM port (cnffrport)

14-4Cisco BPX 8600 Series Reference