Testing with LinkSprinter
Both LinkSprinters still give you quick and dirty test indicators in the form of tri-state LEDs, but your browser is now the place to get more detailed test information. Below are a few examples of how the LinkSprinter can help with your post-installation checklist.
- Do I have power over PoE (Power over Ethernet), and if so, how much?
Not all PoE is created equally, and cable length, kinks, and poor terminations all have an impact on usable power. Knowing how much power is flowing over PoE translates into knowing whether that access point 30 feet in the air is going to work or not.
OFF = no PoE (< 20V)
RED = high voltage (> 57V)
YELLOW = low voltage (< 37V)
GREEN = normal voltage
- Am I negotiating link correctly with my upstream switch?
One of the most basic tests, link is different for gigabit versus 100-megabit connectivity. Make sure link is negotiated over all four pairs for gig, but only two pairs for the older 100 meg.
OFF = auto-off activated after 3-minute timeout
BLINKING_GREEN = waiting for initial link or link lost
SOLID_GREEN = linked OK
- If I'm on a DHCP network, am I getting correctly formed DHCP replies?
Can I get DHCP and can I get it at least three times in a row? What you don't want is your test device "hanging onto the old DHCP" address as you move from data jack to data jack. Once you have an HTML5 browser associated with the LinkSprinter 200, you can reconfigure it for a static address.
RED = DHCP failed after 1-minute timeout, or duplicate IP detected
GREEN= DHCP acquired, or static IP with no duplicate address
- Can I get to my default gateway?
If you can't talk reliably to your default gateway, nothing else matters. You ARP to things in the same subnet as you, but it's the gateway that gets you to the outside world.
OFF = connected to cloud for claiming unit (if DHCP and WWW are both green)
RED = no ping responses (some gateways have PING disabled)
YELLOW = missed one or two pings
GREEN = received all three pings
- Can I get to an Internet resource such as a Web server?
This last test is actually two in one. First, can you do a DNS lookup? Second, can you get to a resource using something like a Web browser? This configurable test can be set up for just about any TCP port or as a simple ICMP ping.
RED = DNS name lookup failed or no ping/port responses
YELLOW = missed one or two ping/port responses
GREEN = received all three ping/port responses
I'm excited that any HTML5 browser can be used to get the full GUI on the LinkSprinter, but it has implications for how test data is stored. If the LinkSprinter were a fat app, you could potentially store test data on your iPhone or Android device. But then, platform support might be limited to those platforms. Fluke made the choice to support any device with an HTML5 browser, but that means the LinkSprinter currently must have a connection to Fluke's LinkSprinter Cloud Service for data uploads. Your HTML5 device is simply the control panel.
I say "currently" because the LinkSprinter is a platform that could morph radically based on market pressures, and I'm hoping that someday an API will be available that allows application developers to create a fat app front end capable of more advanced network testing. What makes this platform so different from a hacked-together Raspberry Pi is that the LinkSprinter can harvest data from the first three layers of the OSI model. Electrical information from Layer 2, LLDP (Link Layer Discovery Protocol) or CDP (Cisco Discovery Protocol) from Layer 2, and ping and WAN connectivity from Layer 3. The Raspberry Pi's Ethernet interface is really USB, and nothing I've found so far has allowed me to get to the electrical portion of the Ethernet interface.
The LinkSprinter doesn't do any data testing at gigabit speeds, but its electrical interface does allow it to probe the interface to see if it will negotiate a link at gigabit speeds. The compromise is that on a gigabit switch, the LinkSprinter will test the gig link, but perform the data testing at 100Mbps instead -- not a horrible compromise, but you should be aware of it.
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