Discover What's Ailing Your Network

In last week's post, I discussed the importance of knowing what's in your network, and gave three easy methods for determining what's resident. But when things go wrong and those approaches don't mesh, you can turn to some easy-to-use tools that can make your troubleshooting efforts more directed and effective. One example is the Netscout LinkSprinter 300 network tester, which includes Wi-Fi support and provides the distance to cable faults.

This is a pretty cool tool that pulls its weight and isolates more than just cable issues.

I recently used the LinkSprinter 300 to test a network that bumped users daily and suffered from application performance slow-downs, while inexplicable event alerts showed up in reporting logs, and multiple erratic connectivity issues popped up. Things on this network just didn't make sense, and too many answers to questions turned out to be assumptions, not fact.

Using the LinkSprinter, I tested an IDF location with a switch stack because I found DHCP from the server wasn't working and ports tested with the LinkSprinter would not bind to an IP address. And, in another switch group, multiple ports were obtaining an IP address from a different and wrong DHCP pool. Within minutes of testing, the LinkSprinter identified these two issues.

The first significant root issue was that the uplink ports were not programmed properly since DHCP was passed to clients on another separate network. Not only were the VLAN definitions off, but port security wasn't effective because VLAN tags for the IP phones were not passing through a hub placed in the configuration since the uplinks were not in trunk mode.

The wrong network IPs were showing up on ports that associated with the embedded staff network and not the guest wireless LAN network. To quickly isolate the activity, we changed the DHCP pool scope in a server. This eliminated another conflict with some IPs that were statically assigned but never removed from the DHCP pool.

Once we resolved the trunking and VLAN definitions the network issues began to disappear and we could switch the DHCP scopes back to their original settings.

This tool doesn't just test cable, it tests and documents the port, switch, and connectivity, showing IP information such as VLAN membership and power supplied over Ethernet..

On the fly, using your smartphone or other wireless device, you can easily annotate the switch, port, and other details for documentation on a switch-by-switch, IDF-by-IDF basis. In addition, using the free cloud and recently improved management console Link-Live, you can view, edit, and manage all test results. The really cool added improvement is the ability to drag (upload) to each test result a photograph or document.

This is the kind of tool that will empower your network team to baseline your cable plant and local network.

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