Category Archives: Networking Stuff

The Copier Man Rings Twice …and Then Some–A Tale of a Spanning Tree Loop (a Sequel Every Millisecond)

Have you ever wondered …what would happen if?  …if say …say

…if say you decide to plug that unknown loose wire into say …some open port on that switch that is conveniently close by? …well let’s just pretend even if you wouldn’t – I mean you are a mere copier printer tech guy …why should you be sloppy and leave loose wires sitting around unplugged? …you remembered unplugging it from the business machine you worked on moments ago and so you know it shouldn’t be loose …its like extra bolts when working on your engine – they gotta go somewhere – that machine is a network aware device and logic might dictate that a network cable should plug into the port on the side that magically happens to have a matching shape to that thing at the end of the loose cable …but that switch has lots of other wires in it – that looks like a better place …right?  I mean it does look inviting. [DOH!]

…so if you take a mini-switch that expands your limited one port wall plate in the corner to use a couple of printers, an IP phone, scanner …etc. you have a time-bomb waiting to detonate your network with ARP traffic.  Perhaps labeling the switch exactly as it is to be used would help to idiot proof it …or maybe taping over the unused ports.  The above fun was done at the expense of a real scenario but the names were changed to protect the guilty.   Unplugging all hosts from the main relay rack switches and adding them back one at a time was the methodology that first brought relief and ultimately led to the conclusion that a spanning tree loop condition existed somewhere out in the office.  The pain of seeing a network go berserk and not know why was unsettling for many hours of down-time until the client remembered that a copier/printer guy had done work the previous day.   It was a matter of minutes then to get things rectified.

Great Tools for the Admin – you get signal .com

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http://www.yougetsignal.com/tools/open-ports/

This is a very nice and handy website based set of tools:

  • Port Forwarding Tester
  • Network Location Tool
  • Visual Trace Route Tool
  • Phone Number Geolocator
  • Reverse IP Domain Check
  • WHOIS Lookup Tool
  • iGoogle Network Information Gadget
  • Windows Network Gadget (Vista/7)

OpenDNS – Why? Can something free be good?

OpenDNS – I use it and like it and yield it like a Zen master:  OpenDNS

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Regardless if any blocking is used, the tool still provides an auditing/oversight function. OpenDNS is a high availability DNS service; it has a very proven track record of dependable service. If there were a cost it would be sellable; however, it’s ‘free as in beer’ so that is an even easier sell. If for nothing else it could be used as an introductory mechanism to helping your client discover the value of such web oversight of his office staff. Some would rather not bother; some will require access to this information on a as-needed basis, some are overreaching power mongers. It’s not a one size fits all thing.

As for if you trust them in their expressed intention of being a good neighbor in the ‘net’ as to their reason for providing this FREE service, that’s for you to sort out. As a skeptic looking for my clients best interests, I’ve not been given any telltale signs of any bait-n-switchery or other less than forthright underpinnings. It seems legit.

One downside I’ve discovered with OpenDNS is with optionally your logo integrated; when done your logo is displayed on an informational html page whenever something doesn’t resolve or is blocked. Although at first I thought this good in that I’d have a track back mechanism for people who were false-positive blocked that would enable finer adjustments, white listing, …etc. However, instead it put me in the position of a web ‘door-man aka bouncer’ of sorts. I really don’t advocate putting yourself in that front and center thug/gate-keeper position unless you have a service agreement in place as well as some pre-existing expectations, instructions, and explanations as to the who?, what?, and why? of web filtering in writing and distributed to all under your wise and almighty judicious power. :)

Wirelessness – what tha? dual band? 2.4 or 5GHz “n”?

Having been doing some shopping for a wireless network of late I thought I’d try and discover what the whole “dual band” ‘n’ router thing was and why I would benefit from buying one especially since the costs are much higher than a single band ‘n’ model. In the process I’ve learned a lot more about bandwidths and the pro’s and con’s of 2.4GHz versus a 5GHz band. I didn’t know the draft ‘n’ specification includes both radio frequency bands; furthermore, it doesn’t necessarily require operation on both. Yes, that means it could be either one and this is of course pretty important to connecting a transmitter with a receiver (networking). I’ve also learned that there aren’t many 5GHz ‘n’ products on the market if there are any at all.  Let me Google that for you.  I’ve also learned that the promise of a 5GHz HOV styled expressway for wirelessness is in reality less than fantastic in that the higher bandwidth 5GHz doesn’t penetrate through walls as well nor go quite as far as 2.4GHz.

Here’s some more 5GHz food for thought – http://blogs.zdnet.com/Ou/?p=411

The next ongoing discovery was that Linksys (and others aka NetGear do the same) sells and promotes their simultaneous “dual band” expensive high-margin router (WRT610n) promising the ability to get better HD video streaming and oimagenline gaming performance on the relatively empty 5GHz band versus the crowded 2.4GHz band. …that sounds great The hollow and empty promise truth is that Linksys doesn’t sell a single 5GHz N network adapter (WMP300N is 2.4GHz) except for notebooks; you aren’t going to be throwing a simple adapter into that gaming rig box at your or your boy’s desk. That’s right and you are probably now connecting the dots. …all hype and no delivery Worse yet, you cannot easily find what band their “N” adapter offerings operates at (whether 2.4GHz or 5GHz); at least not from any of the product literature, spec sheets, and packaging that I’ve looked over (some mfg’s do provide this). Lacking a desired decent desktop adapter card, your only option then is to purchase another 5 GHz router and use it as a bridge with its wired ports.  In fact this is kinda what NetGear is selling as a “kit”.

bah humbug!  …this is one frustrated & frequency fatigued shopper