Review : Monitor brings large WANs under control

Network Instruments’ Link Analyst 5.1 is a network monitoring system that provides administrators with a range of inventory, reporting, and device and network route mapping capabilities. On top of this, it can perform some basic asset management roles and offers configurable alarms for alerting managers when thresholds have been breached.

Released in March, Link Analyst 5.1 can integrate with other Network Instruments systems, such as its Observer network packet analysis system and its GigaStor appliance for deep packet and forensic analysis of 10 Gigabit Ethernet, wide area network and storage area network connections.

Link Analyst supports Windows XP Professional and Vista, as well as Windows Server 2003 and 2008. We installed the software on several desktop systems running XP Professional and a standard Intel server running Windows Server 2003 Enterprise Edition.

According to the vendor, Link Analyst 5.1 is suitable for businesses of all sizes, but it is larger enterprises that stand to benefit most from deploying the system. For example, the most impressive new feature in this version is Business Groups, which allows network managers to map devices according to a range of criteria such as network subnet, geographical location or type of device. This feature is aimed particularly at senior network managers within large enterprises who have to oversee distributed branch offices or even separate business divisions in different countries. Business Groups allows these managers to create groupings that reflect such divisions, and authorise local network managers to have admin rights to their devices and network connectivity.

We created an IT Week group using a wizard to discover and categorise all the devices fitting this group. Initially, the wizard asked whether device discove ry alone was required, or device discovery and an associated topology. The latter is needed to produce a diagram of users’ connectivity, rather than just a list of devices.

Users need to supply the correct Simple Network Management Protocol (SNMP) credentials for managed devices. Unmanaged switches or routers will not be picked up. Link Analyst supports all versions of SNMP, and also allows administrators to use Microsoft Windows Management Instrumentation (WMI) credentials when performing device inventories or setting up alarms.

As with all network monitoring systems, users can define which IP subnets to check when discovering devices. The software can also be used to discover different services running on the network, such as Domain Name System (DNS) and Simple Mail Transfer Protocol (SMTP). We found it easy to add other services, such as File Transfer Protocol (FTP), by specifying which TCP port to check.

As well as device availability, Link Analyst can also provide detailed information about internal LAN connections and any associated WAN connectivity problems.

After a network map has been produced, users can define which devices or network connections they want to poll in order to monitor availability. For network connections, Link Analyst can be configured to monitor a variety of switch and router parameters. Examples include network port utilisation, or the ability to monitor network performance between two devices, which could be used to track quality of service for IP telephony traffic or service level agreements on WAN connections.

Link Analyst can be delivered as a web service for remote users, allowing them to view graphs of network utilisation by device or application. Reports can also be generated over user-definable time steps, to view trends for specific network, device or application parameters.

When it came to configuring alarms, we found it easy to set up the system to check the utilisation of specific network ports and trigger an email warning when traffic exceeded a specified high or low threshold. Link Analyst also allows notification alarms to be delivered to phone pagers.

Link Analyst can also be used as an asset management tool. It provides a simple way for administrators to find out what packages are installed on network-attached systems and the amount of bandwidth each is using. It can also check for availability of network applications such as SQL Server. However, it does not possess the advanced functionality of bespoke IT asset management packages, such as the ability to remotely install software packages.

On the whole, we found the user interface clean and simple to use, and consistent with that used by Network Instruments’ Observer packet analysis and application performance monitoring package. We also installed Network Instruments’ Observer 12 on our test system, which allowed us to define an IP subnet filter and then run a packet capture that collected IP packets only with IP addresses defined by our filter.

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