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SNMP (Simple Network
Management Protocol) is a standard way for computers to share networking
information. SNMP is used to retrieve and monitor interface uptime statistics of
a MeshAP node. Some network administration services it provides are the
follow:
 | Supervises
the basic and extended parameters of the router and its interfaces
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| SNMP
GET BULK request can be used
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| Raise
alarms on critical situations (router's CPU overload, router's RAM
exhausted, interface go to 'down' state) and send alert via e-mail
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| Act
as SYSLOG daemon: receive and log SYSLOG messages
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| Receive,
analyze and log SNMP traps
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| Repeaters
monitoring, control of repeater's ports
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| Searching
of MAC addresses
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| Ping
monitoring
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| TCP
connection table monitoring
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| SNMP
parameter history, graph and log
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In SNMP, they are two
types of communicating devices exist: agents and managers. An agent provides
networking information to a manager application running on another computer. The
agents and managers share a database of information, called the Management
Information Base (MIB).
Locustworld uses
Simple Network Management Protocol SNMP agent that supports SNMP version 1 and
SNMP version 2 based on standards for communication with devices connected to a
TCP/IP network, like routers, hubs and switches. Some SNMP software is designed
to handle a wide variety of devices.
Locustworld MeshAP SNMP only supports read mode. SNMP - Simple Network
Management Protocol
Since it was
developed in 1988, the Simple Network Management Protocol has become the
standard for Internet work management. Because it is a simple solution,
requiring little code to implement, vendors can easily build SNMP agents to
their products. SNMP is extensible, allowing vendors to easily add network
management functions to their existing products. SNMP also separates the
management architecture from the architecture of the hardware devices, which
broadens the base of multi-vendor support. Perhaps most important, unlike other
so-called standards, SNMP is not a mere paper specification, but an
implementation that is widely available today.
SNMP Protocol
SNMP is based on the
manager agent model. SNMP is referred to as "simple" because the agent
requires minimal software. Most of the processing power and the data storage
resides on the management system, while a complementary subset of those
functions resides in the managed system.
To achieve its goal
of being simple, SNMP includes a limited set of management commands and
responses. The management system issues Get, Get Next and Set messages to
retrieve single or multiple object variables or to establish the value of a
single variable. The managed agent sends a Response message to complete the Get,
Get Next or Set. The managed agent sends an event notification, called a trap
to the management system to identify the occurrence of conditions such as
threshold that exceeds a predetermined value. In short there are only five
primitive operations:
get
(retrieve operation)
get
next (traversal operation)
get
response (indicative operation)
set
(alter operation)
trap
(asynchronous trap operation)
SNMP Message Construct
Each SNMP message has
the format:
| Version
Number |
| Community
Name - kind of a password |
| One
or more SNMP PDUs - assuming trivial authentication |
Each SNMP PDU except
trap has the following format:
| Request
id - request sequence number |
| Error
status - zero if no error otherwise one of a small set |
| Error
index - if non zero indicates which of the OID’s in the PDU caused the
error2 |
| List
of OID’s and values - values are null for get and get next |
| Trap
PDUs have the following format: |
| Enterprise
- identifies the type of object causing the trap |
| Agent
address - IP address of agent which sent the trap |
| Generic
trap id - the common standard traps |
| Specific
trap id - proprietary or enterprise trap |
| Time
stamp - when trap occurred in time ticks |
| List
of OID’s and values – OID’s that may be relevant to send to the NMS |
| Outline
of the SNMP protocol |
| Each
SNMP managed object belongs to a community |
| NMS
station may belong to multiple communities |
A community is
defined by a community name, which is an Octet String with 0 to 255 octets in
length.
Each SNMP message
consists of three components
| Version
number |
| Community
name |
| Data
- a sequence of PDUs associated with the request |
Security levels with
basic SNMP
| Authentication |
| Trivial
authentication based on plain text community name exchanged in SNMP messages |
| Authentication
is based on the assumption that the message is not tampered with or
interrogated |
Authorization
Once community name is validated then
agent or manager checks to see if sending address is permitted or has the rights
for the requested operation
"View" or "Cut" of
the objects together with permitted access rights is then derived for that pair
(community name, sending address)
To install SNMP in MeshAP Node
With your web browser Log into
Wiana.org
Select the node that you want to install SNMP software module
Select Software Module Manager
Congratulations. After
the rebooting your MeshAP the software will install and it is now time to test
your SNMP connection.
Installing Monitoring Tool
For this exercise the assumption is you’re SNMP monitoring
tool is install. I current
evaluating the software from www.innerdive.com/products/ric/
. It is current running on Windows
2000 machine. Once the software is
installed and running it simple as adding the router information, which in this
case is the MeshAP uplink node, that SNMP agent was installed.
There is some simple configuration information that you need
to provide. They are:
Once
information is added to the router the reporting tool starts to gather
statistics. You can monitor this
static manually or have the software email you when there is a problem. Very little effort is require getting the monitor up and
running. It adds a new dimension to monitoring the mesh.
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