Network monitoring systems and
network testing technologies have evolved greatly over time,
offering more automation, more ways to test servers and systems,
and more ways to alert network administrators, sysadmins and IT
managers of
problems with the network and internal systems.
What is network monitoring?
Network monitoring uses an
IT system or systems to constantly
monitor a computer network for slow or failing components. It
can check components including like application, email or web
servers, peripherals and the
health of the network itself.
The systems can be set to notify the network administrator in
case of outages via email, pager or other means.
What sorts of problems cause network or IT failures?
Network monitoring systems monitor the network for problems
caused by overloaded and crashed application servers, web servers
or other systems, or issues with network connections and other
devices.
These problems might be caused by faulty equipment or even human
error.
How do network monitoring systems work?
They tend to check the activity and health of internal systems
via the network by sending a signal, called a ping, to various
system ports.
The
testing system uses a huge variety of check intervals, which is
basically the time between pings. This could vary from every four
hours to every single minute.
Typically, most network monitoring
services test the server anywhere between once every hour to
once a minute.
Which network protocols do network monitoring systems
check?
Network monitoring systems can check all manner of network
protocols, particularly
internet protocols.
For example, web site monitoring services can check HTTP pages,
HTTPS, SNMP, FTP, SMTP, POP3, IMAP, DNS, SSH, TELNET, SSL, and
TCP.
So, when it comes to web servers, a network monitoring program
may send am HTTP request to a web server to determine its
status.
But when it comes to an email server, the monitoring software
may periodically send a test message through SMTP, but which is
retrieved by IMAP or POP3. By doing this it can emulate the path of
a typical message and check the health of the networks and servers
it passes through.
What do network monitoring systems measure?
The most frequently measured metrics are to
check the response time and availability, or uptime, of a
server.
Network monitoring also checks for the consistency and
reliability of application servers and IT equipment.
What happens when a system fails?
If a network monitoring tool detects a problem with a system,
via a status request failure, for example when a connection cannot
be established, this results in a time out.
Most users will see a time out when they try to access a web
site service or application which is struggling to respond, or send
an email to a recipient with email server issues that delay or stop
the message going through.
In cases where there is a status request failure, the network
monitoring system will produce an action.
These actions can vary, and might involve actively trying to get
the network manager’s attention via an alarm – an SMS text, a pager
message or an email.
Alternatively, automatic failover systems may be activated to
remove the troubled server from duty until it can be repaired.
Commercial and Open Source Network Monitoring Tools:
- HP OpenView
HP OpenView is one of the more established commercial monitoring
platforms, and has many features. It has been around for 15 years
and is now the foundation of part of HP's BTO product
line.
- MRTG
The Multi Router Traffic Grapher (MRTG) monitors and graphs traffic
on network links. It also creates daily, weekly, and monthly
graphs.
- Nagios
Nagios is an open source system that offers network monitoring and
notification and problem management. Nagios runs on Linux and has
been around for over 10 years, with a large user base and support
community.
- OpenNMS
OpenNMS is an open source network monitoring platform aimed at
enterprises. It has a strong user and open source community support
group.
- SolarWinds
SolarWinds Orion Network Performance Monitor (Orion NPM) is
designed with simplicity and ease in mind. Solarwinds itself is
known for many strong free network tools.
- Spiceworks IT
Management
Spiceworks is a free, (ad sponsored) network monitoring and issue
tracking platform. It has a large and active user community and a
highly customisable interface.