Routers and switches and hubs, oh my!
I bet you hear this as often as I do: "So I need to put a little
hub over there to fan out the network?". I know they probably
can't buy a hub nowadays anyway, but I still feel like I need
to correct them: "No, you need a little switch".
There's a difference, of course. A hub is a bus, where every
packet goes to every port. With a switch, only broadcast packets
go to every port, and with a managed
switch, even that's not necessarily true because you can control what goes where.
But as I said, if they pop down to Radio Shack or Staples or CompUsa,
they are only going to find switches, so I could probably save my
breath and safely nod agreement. You never know, though: the other
day I had a call from someone asking if they should plug their cable
modem router into an uplink port or a regular port. I of course asked
what on earth he was doing with something old enough to even have
an uplink port, and was told "it was free", which is a pretty good
answer, I guess.
What has bitten me now and then is stray routers employed as
switches. At one customer, I've been bitten three times by the
same old router. I took the darn thing out of service years ago
and replaced it with something better, but told the IT guy to
keep it because, what the heck, it's a quick swap-in spare if
his current router were to fail. It wasn't too surprising
to me when that IT guy left shortly thereafter; he was really
too bright for the job he had. I never thought about that router,
but it wasn't long before somebody needed to extend a few machines
at an inconvenient spot and used that "hub" to accomplish it. A few
machines managed to get their ip address and gateway from that old router,
but of course couldn't get out to the internet any more,
and it and the real router squabbled over their own ip, as
did machines that got the same ip from different routers. Damn
mess, but I found it pretty quickly, chastised the responsible
party, and told them not to do that again.
Yeah, like that's going to work. A few months later it
happened again. Different part of the building, but the same
old router reincarnated as a "hub". This time I put a sign on
it: "This is a router - it cannot be used as a switch or a hub".
I figured that would keep it safe. Nope. Three months later
it turned up again. Different culprit, and the sign mysteriously
missing. I Scotch-taped the hell out of that note; somebody worked
hard to take it off.
This time I went to an old hand at the plant. I explained
again what had happened, and he shook his head in sympathy. "You
know", I said, "it would have been better if somehow this had
accidentally been thrown away. Like maybe if it just got bumped
off the edge of this desk and landed in the trash.."
I turned my back and walked away. As I reached the door I
heard a soft thump, perhaps made by something small landing in
a partly filled wastebasket.. or perhaps not. We'll see.
If this page was useful to you, please help others find it:
More Articles by Tony Lawrence
- Find me on Google+
This is a Unix/Linux resource website. It contains technical articles about Unix, Linux and general computing related subjects, opinion, news, help files, how-to's, tutorials and more. We appreciate comments and article submissions.
Jump to Comments
Many of the products and books I review are things I purchased for my own use. Some were given to me specifically for the purpose of reviewing them. I resell or can earn commissions from the sale of some of these items. Links within these pages may be affiliate links that pay me for referring you to them. That's mostly insignificant amounts of money; whenever it is not I have made my relationship plain. I also may own stock in companies mentioned here. If you have any question, please do feel free to contact me.
Specific links that take you to pages that allow you to purchase the item I reviewed are very likely to pay me a commission. Many of the books I review were given to me by the publishers specifically for the purpose of writing a review. These gifts and referral fees do not affect my opinions; I often give bad reviews anyway.
We use Google third-party advertising companies to serve ads when you visit our website. These companies may use information (not including your name, address, email address, or telephone number) about your visits to this and other websites in order to provide advertisements about goods and services of interest to you. If you would like more information about this practice and to know your choices about not having this information used by these companies, click here.