[ale] [Semi-OT] Networking Equipment

[Michael B. Trausch]

On Tue, Nov 29, 2011 at 03:47:27PM -0500, David Tomaschik wrote:
> I consider myself a pretty good system administrator and a decent
> developer.  What I am not is a networking guy.  At the risk of
> spreading myself too thin, I want to learn more about the networking
> side of things.  (It helps as a system administrator to know what is
> going on on the stuff your servers are connected to.)  While I know
> the academic/general side of things like VLANs and STP, I haven't
> had any opportunity for practical experience.

My advice: learn the stack and the protocols within it.  This will
help you more than learning anything that is vendor-specific, because
you'll be able to see and understand what's going on and where.

Don't make the mistake that so many do and assume that IP is opaque
and that you need not know about it.  The measure (again, IMHO!) of a
good sysadmin/netadmin is that as little of the system (or network) as
possible is opaque to them.  Now, I am not saying that you need to be
an expert in every aspect of the network stack, but you should at
least know how to recognize what's what and where to look for more
information if you need it.

Perhaps even more important than the focus on networking, keep your
knowledge of the RFCs up to date if you can.  I refer to the things
all the time, though I'll admit that I haven't read as many as I
want.  But, you can keep track of changes by monitoring the Daily Dose
of IETF, which talks about new RFCs, new drafts, and so forth.  A most
excellent resource.  (And if you haven't really looked at the list of
current RFCs, there are standards for things you might not of thought
of there...)

The RFCs cover virtually every topic you would be interested in, from
Ethernet framing to virtual network protocols, IP (both v4 and v6),
transport protocols, routing, switching, bridging... more than you can
comfortably read in a month.  But get a reader or a tablet or
something and do spend time reading them.  They provide great insight,
and as with anything, the more you know about the stack the more the
higher-level constructs within it become predictable and make sense.
And if you understand how all of the layer-2 things work (again,
generally speaking) you don't have to really know any one vendor's UI
to diagnose and fix a problem.  Diagnose the L2 issue, and then you
can figure out how the device can be fixed to work around it (if it
indeed can be, assuming it's something that isn't Linux).

> I'd like to get my hands dirty, so I'm looking for one (or more)
> cheap managed switches.  Cisco probably preferred, since they have
> the lion's share of the gear out there, but I'm open to other
> suggestions.  I know there are some switches for around $50 on eBay,
> but most of those seem to be ancient and I'm not sure how relevant
> they are to what's out there today.  (i.e., devices that went
> end-of-sale a decade ago.)  Of course, the basics might not have
> changed too much.  I'm not looking to go CCNA or really work as a
> network guy, just to know enough to have a good grasp of the network
> side and maybe to do some small business scale tasks.

Go to the store and pick up a router that will run DD-WRT and
experiment, experiment, experiment.  Great way to do it "on the cheap"
and of course most of the stuff that Linux exposes is something that
Cisco's ios is capable of doing.  Or so I've heard, anyway.

> Can anyone suggest a source for cheap used networking gear?  Or
> alternatively, suggest models of switches worth looking at on
> eBay/other?

I'd start with the DD-WRT list of supported routers, and get the
largest one that you're comfortable playing with.  Seriously.  You can
then do things like play with VLANs and firewalling and routing and
whatever else you can imagine.  If you want to expand your experiments
to include Cisco equipment later, you can, and IIRC the Linux kernel
can create tunnels using Cisco's custom tunnel protocol.

    --- Mike
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