# Configuring NMS SNMP

Use the SNMP configuration file snmp.cfg to set the IP/UDP ports used by the multiplexer to communicate with the master agents, to receive or send SNMP requests, and to communicate with the NMS subagents.

You can also use snmp.cfg to:

- Set the write access for a given subagent using a community name

- Set the trap destination for one or more subagents

- Set information specific to a given MIB (for example, the Chassis MIB information)

snmp.cfg is installed in one of the following directories:

Operating system | Directory
--- | ---
Windows | \nms\ctaccess\cfg
UNIX | /opt/nms/ctaccess/cfg

## Configuration file syntax

Statements within the file display one to a line. Text appearing after a number sign (#) is a comment and is ignored. Statements are not case sensitive, except where operating system conventions prevail (for example, file names under UNIX).

snmp.cfg is divided into sections. Each section has a header in square brackets ([ ]). The statements in each section apply to one or more subagents. The following table provides a description of the snmp.cfg sections:

Section | Subagent(s)
--- | ---
[common] | All subagents
[chassisAgent] | Chassis subagent only
[ds1Agent] | Trunk subagent only
[oamAgent] | OAM Database subagent only
[softRevAgent] | Software Revision subagent only
[rtpAgent] | RTP subagent only

Statements in a section consist of a keyword name followed by an equals sign (=) and then a value:

keyword = value

### The [common] section

The [common] section contains statements that apply to all subagents:

Keyword | Description | Mandatory?
--- | --- | ---
SnmpPort | Defines the port through which SNMP queries are sent to the multiplexer. Allowed values: Valid UDP port number | Yes
MasterAgentPort | Defines the port through which the multiplexer sends SNMP requests not addressed to its subagents. Allowed values: Valid UDP port number | Yes
CommunicationPort | Defines the port used by the multiplexer, the subagent, and the console to communicate (for registration, stop, or information commands). Allowed values: Valid UDP port number | Yes
access | Defines the access rights and the defined communities that can be used to send requests to the agents. Allowed values are: access,community,host where: access defines the access right: readonly, writeonly, or readwrite community is the name of a defined community that can be used to send requests to the agents host specifies the name of the host where the SNMP requests are authorized. An asterisk (*) character indicates that any host is allowed. | No
trap | Defines the host where the trap is sent and the community that is used. Allowed values are: host,community where: host specifies the name of the host where the SNMP requests are authorized. You must specify either an IP address or IP address mask for the host in the trap. community is the name of a defined community that can be used to send requests to the agents. | No

### The subagent-specific sections

Sections containing statements that apply to individual subagents only display below the [common] section. Any configuration parameters needed by a given subagent must appear in the section for the subagent.

The access and trap keywords (defined in the [common] section) can also appear in the subagent-specific sections to define additional access and trap host settings for individual subagents only. Traps from a given subagent are sent to all hosts listed in the section for the subagent, as well as the hosts listed in the [common] section.