Chapter 30 System
USG20(W)-VPN Series User’s Guide
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An SNMP managed network consists of two main types of component: agents and a manager.
An agent is a management software module that resides in a managed device (the USG). An agent
translates the local management information from the managed device into a form compatible with
SNMP. The manager is the console through which network administrators perform network
management functions. It executes applications that control and monitor managed devices.
The managed devices contain object variables/managed objects that define each piece of
information to be collected about a device. Examples of variables include such as number of
packets received, node port status etc. A Management Information Base (MIB) is a collection of
managed objects. SNMP allows a manager and agents to communicate for the purpose of accessing
these objects.
SNMP itself is a simple request/response protocol based on the manager/agent model. The
manager issues a request and the agent returns responses using the following protocol operations:
• Get - Allows the manager to retrieve an object variable from the agent.
• GetNext - Allows the manager to retrieve the next object variable from a table or list within an
agent. In SNMPv1, when a manager wants to retrieve all elements of a table from an agent, it
initiates a Get operation, followed by a series of GetNext operations.
• Set - Allows the manager to set values for object variables within an agent.
• Trap - Used by the agent to inform the manager of some events.
30.11.1 SNMPv3 and Security
SNMPv3 enhances security for SNMP management using authentication and encryption. SNMP
managers can be required to authenticate with agents before conducting SNMP management
sessions.
Security can be further enhanced by encrypting the SNMP messages sent from the managers.
Encryption protects the contents of the SNMP messages. When the contents of the SNMP messages
are encrypted, only the intended recipients can read them.
30.11.2 Supported MIBs
The USG supports MIB II that is defined in RFC-1213 and RFC-1215. The USG also supports private
MIBs (zywall.mib and zyxel-zywall-ZLD-Common.mib) to collect information about CPU and
memory usage and VPN total throughput. The focus of the MIBs is to let administrators collect
statistical data and monitor status and performance. You can download the USG’s MIBs from
www.zyxel.com.
30.11.3 SNMP Traps
The USG will send traps to the SNMP manager when any one of the following events occurs.
Table 247
SNMP Traps
OBJECT LABEL
OBJECT ID
DESCRIPTION
Cold Start
1.3.6.1.6.3.1.1.5.1
This trap is sent when the USG is turned on or an
agent restarts.
linkDown
1.3.6.1.6.3.1.1.5.3
This trap is sent when the Ethernet link is down.
Summary of Contents for ZyWall USG20-VPN
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