Modern corporate networks have become much more dynamic than they used to be. This makes it harder for sysadmins and network admins to know what's connected to the network.

Devices connect and disconnect from networks much more often, particularly in workplaces with Bring Your Own Device (BYOD) policies, where employees can connect personal devices such as laptops and cell phones.

The types and varieties of devices have expanded also. In addition to computers and workstations, the typical network includes printers, copiers, routers, switches, VoIP boxes, and other managed appliances.

Doing a Network Inventory

At some point, any network administrator will need to do an audit of all these connected network devices. Logging and tracking all devices is essential for configuration management, capacity planning, and security. You need a tool to do this even if you have been diligent in logging devices as they are connected. It can be a bit of a shock to see what is actually on your network.

A network discovery tool can find and identify everything connected to your network, produce a topology of how they are connected to each other, and produce detailed reports for planning purposes. It is an essential tool for network management.

Basics About Device and Network Connectivity

When a device is plugged into the network, a Dynamic Host Configuration Protocol, (DHCP) server issues it an IP address. This address is unique on this network, which is not to say that there isn’t a device anywhere in the world that doesn’t have this same number assigned to it by its own network.

What actually is unique is the media access control (MAC) address. Every device’s network adapter has a unique MAC address. So, while the IP address is determined by software, and can change, the MAC is determined by hardware, and can’t be changed.

It’s analogous to the difference between a password vs. a fingerprint as identification for a person. And just as multifactor identification is most secure for people, using both IP and MAC addresses gives the best view into a network.

Network Discovery, Network monitoring, and Asset Management

A network discovery tool uses several processes to investigate and understand the network of interest.

Simple Network Management Protocol (SNMP) is probably the most important. Most network devices are SNMP-enabled. It is the Internet standard protocol that provides monitoring for nodes or connection points, like servers, routers, bridges, and hubs, on an IP network

Ping is a familiar tool in network management, and automatically checks every device’s status and whether it is online.

Address resolution protocol (ARP) uses SNMP to query device caches to build a database of MAC addresses. Knowing which devices are neighbors to others enables the discovery of the networks’ topology.

WhatsUp Gold’s discovery process generates a complete inventory of all networked devices including device type, vendor, serial number, firmware and hardware rev, and the modules installed on the devices. Customers often use this feature to fulfill inventory audits with automatically generated reports on the software installed on servers or network devices.

At the completion of the discovery process, WhatsUp Gold automatically assigns devices roles that specify what data to collect and remedial actions that are enabled. You can easily modify default device roles and sub-roles or create new ones with the Device Role Editor. The discovery process also identifies dependencies that are marked on the map as directional arrows. With a couple of mouse clicks, dependency data can be used to suppress unnecessary alerts saving valuable troubleshooting time by minimizing false alerts.

Hardware Topology Discovery

Building network topology maps helps you gain a better understanding of your network. Tools like WhatsUp Gold use a combination of layer-2 and layer-3 topology to determine which devices are connected to which other devices. The layers come out of the classic Open Systems Interconnect (OSI) model used to both design and understand networks.

On the most basic level, layer 2 protocols discover data links and port-to-port connectivity, and work with MAC addresses. Layer 3 protocols assist in discovering neighboring devices, and work with IP addresses. For example, using Layer 3, you can query SNMP-enabled devices in order to build up a network map that includes device location, attributes, and role.

While layer-3 protocols are widely used, layer 2 protocols tend to be more proprietary, so the use of the Link Layer Discovery Protocol (LLDP), as WhatsUp Gold does, is essential to ensure that device information is available to neighboring devices from other manufacturers.

Using integrated layer-2 and layer-3 analysis gives full visibility into physical, logical, and virtual connectivity, so you can generate a topology map that accurately reflects network function.

WhatsUp Gold network discovery builds up a complete picture of the network through a variety of innovative Layer 2/3 discovery technologies, including ARP, SNMP, SSH, Virtual Infrastructure Management, IP addressing, ICMP and LLDP in combination with vendor-proprietary mechanisms.

Continuous Network Monitoring and Asset Management

Most sysadmins now manage heterogeneous networks, with various types and models of device from many different vendors. Since very vendor has its own naming styles, if you aren’t diligent renaming devices to your own consistent convention, what you will see when you examine it is an alphanumeric soup of various inconsistent designations. Getting IT staff to do this routinely can be surprisingly difficult. A network discovery can certainly help, but only supplements your network management processes.

And, as you should have a standard naming convention for devices on your network, you should also try to keep to a standardized topology. Software like WhatsUp Gold Network Discovery Tool provides visualization capabilities to give you a graphical display of network layout. A predictable standard topology will make it much easier to understand the status and identify potential problems. This is particularly important in commercial applications, like ecommerce sites.

Look for a tool like WhatsUp Gold has a robust reporting function. This product can generate more than 200 different types of reports, depending on need. You know that you can easily generate more information than anyone else can comfortably incorporate into their own planning. Make it easy on your counterparts with reports tailored to their needs.

Scan your network regularly, using this as a network monitor tool. You should be a network administrator, not a network detective. Network discovery is far from the only challenge a sysadmin faces. Learn more about the rest with the IT Pro’s Guide to Faster Troubleshooting ebook.


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