B.11 NTP/PTP Server
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B.11.5
SNMP Support
This section provides more detail about Simple Network Management Protocol (SNMP). SNMP was created
to provide a standard for managing different networks and the devices on the networks. As such, SNMP is
designed to operate on the application layer using different transport protocols (e.g. TCP/IP and UDP),
making it independent of network hardware.
An SNMP managed network consists of three components: A managed device, an agent and a network-
management system (NMS). The clock is a managed device running an SNMP agent that responds to queries
from the network-management system.
SNMP Version Information
Currently, there are three versions of SNMP defined: SNMP v1, v2 and v3. The clock supports these three
versions. Here are some differences between versions.
SNMP v1. Basic Operations and Features
GetUsed by the NMS to retrieve the value of one or more object instances from and agent.
GetNextUsed by the NMS to retrieve the value of the next object instance in a table or a list within
an agent.
SetUsed by the NMS to set the values of the object instances within an agent.
TrapUsed by agents to asynchronously inform the NMS of a significant event.
SNMP v2. Additional Operations and Features
GetBulkUsed by the NMS to efficiently retrieve large blocks of data.
InformAllows one NMS to send trap information to another NMS and to then receive a response.
SNMP v3. Security Enhancement
User-based Security Model (USM) for SNMP message security.
View-based Access Control Model (VACM) for access control.
Dynamically configure the SNMP agents using SNMP SET commands.
Management Information Base (MIB) Table
Object names are stored in a (MIB) table that reside on a computer, and correspond to values in a managed
device. The agent in the NTP/PTP Server will respond to queries from the management program to return
values of these objects. Currently, management programs may only read the status of the clock and not
configure settings. See Section B.11.5 for a print out of the current MIB table. A soft copy of the MIB table
is available to download from the Arbiter Systems website at the following address: www.arbiter.com.
SNMP Service
Descriptions that follow are based on the web interface. The SNMP service (agent) runs on the NTP/PTP
Server when enabled in the configuration. Figure B.18 illustrates the SNMP Status screen, which shows that
both the SNMP service and traps are enabled. To view the SNMP Status screen, log in to the NTP/PTP
Server with the web interface and select the SNMP tab on the left.
Note that SNMP configuration is available only through the web interface.
SNMP Traps
SNMP Traps (v1) or Notifications (v2) may be used to:
send notification of a change