and Switches and Hubs, Oh My!
A short while back, networks were as flat as the Kansas prairie, and computers on them were a lot like early prairie farmsteads: few and far between, pretty much speaking to each other only when they had to. (Business looks good again this year. Yep.) Most systems still used dumb terminals, and when speaking to anything outside the LAN, system-to-system modem connections were the way to do it.
A tornado named the
Internet suddenly appeared in this landscape. It uprooted established
standards and practices, swept aside protocols and speed limitations,
and took us into a Technicolor networking landscape very different
than what was there before.
Smaller companies were tossed before the tornado to eventually land and quickly begin growing again in the new environment. Large companies like IBM, HP, Digital, and Microsoft, who were rooted and established in their own proprietary standards (it sounds like an oxymoron, but its true) survived by generally ignoring the howling winds. Eventually, munchkin-like, they all came out to see what the general fuss was about, and found that a house-sized chunk of change (pun intended) had landed.
Networking, and the TCP/IP
protocol had truly arrived in style, bringing strange new
applications and markets. Serial connections and proprietary
networking (What do you mean we dont need SNA to connect
to the Wichita office anymore?) gave way to a new kid on the
block. And her little dog, too.
So here we are,
sitting in a strange new networking land of strange new networking
things. And for some of us, trying to understand the whole of it all
especially in relation to legacy system like the
HP e3000 is a little daunting. What are all these networking
black boxes we plug the system into, and what do they all do? How can
they make life better? (How can they make life worse?) If youre
not sure (or just plain curious) read on.
The networking wizard
of your HP e3000 system is a program named NMMGR. It
allows you to define networking hardware and tells you how to create
connections with them. But what things can you define? Before we talk
about connecting to things, we should probably take a crash-course in
the things youre connecting to.
The basic networking boxes youll connect to are hubs, routers, switches, bridges, and gateways. Oh My. Lets take them one at a time.
Since life is like an analogy, Ill stretch one for the hub to go like this: If your network traffic is like water through a hose, then a hub is like a splitter, allowing multiple exits. Generally speaking, a hub simply splits the traffic from the incoming line into each connected port out. This is cheap and simple to set up if you dont have a lot of connections, but like too many divisions on any hose, too many hubs will make the end connections anemic. The fewer connections the better, so most hubs have no more than 24 ports total.
Obviously, to make
things better for all connections in larger networks, more
water pressure was needed and the switch was
No, Im not talking about the System Administrator. A switch looks very similar to a hub, but the appearance ends there. Again, if your network is like a stream of water in a hose, then your garden-variety switch is like a water tank, adding pressure to the line. Huge water tanks are placed at the heart of a citys water system, while small tanks are placed on buildings. At the heart of most networks tended by a cooing Network Administrator is a core switch (the main tank).
group switches (building-sized tanks) can be used in wiring
closets for special-need areas of the network. So, although a hub and
a switch both offer multiple connections, the resulting
streams have vastly different origin and force. Now that
were one big speedy networking family, no one minds if it all
fails, right? No? Well love can build a bridge, and so can
Having all your network
connections on one physical segment isnt too grand
especially when it fails. By segregating physical networks and then
bridging them together, you ensure that in the face of
adversity, some people can still laugh at the ones who cant
work. Aquariously speaking, a simple bridge is like a valved pipe
between two water systems, passing water in both directions, and
shutting one sides valve if that system loses
pressure (goes down). You say you want to route water based on
content? Well then.
Simply put, a basic
router is an intelligent (logically) one-way bridge, examining
network data information and very quickly sending data packets down
one line or another. In our epic analogy, a router could be a thermal
valve, forcing only cold water to flow this way, and hot water that
way, preserving us from the heartbreak of tepidity. Since the router
has to work quickly, it usually works at a lower level than other
equipment does, caring less about content and more about destination.
You say youd like to exchange hot water with someone else?
Youd like the gate to swing both ways?
A router is excellent at sending packets from Here to There (and not necessarily Back Again), but nothing beats the gateway for two-way communication. A gateway takes data from one network and sends it to another, even re-creating the data packet on the other side, if need be. To stretch our analogy to its limits, we could say that two different water systems exist, having the same characteristics, including temperature. One system is chlorinated, while the other is not, and so simply allowing the water to pass unmolested would be an issue one system would become diluted, and the other exposed. What we need is a filtration pump that allows the water to be pumped in either direction, adding chlorine one way, and taking it out in the other direction.
Connecting to the Internet requires a gateway, since your home network doesnt know how to reach something out there. What it does know is how to hand off a data packet destined for Not Here to a gateway for processing. The gateway in turns checks the packets address and sends it to the best possible network closer to the packets Ultimate Destination, re-labeling the packet as it does so, and putting its own address in the packets return address. If the packets Ultimate Destination isnt on the new network either, then the gateway there does the same thing until the packet finally hits the Emerald City.
On its way back home,
because of all the return addresses it picked up, the
packet passes back through each gateway that it came from until,
clicking its little ruby slippers, the packet realizes it is in no
place but home.
Because of its intensive
examination work, a gateway is almost always dedicated to its task,
especially on larger networks. It was the gateways filtering
abilities that led to using them as a firewall to protect networks by
purposefully filtering and/or denying different types of connections
and data. But the firewall is a topic all its own just make
sure you use one!
So there you have it Networking Devices 101. Now that you know what you can connect your e3000 to, you can come up with some ideas on how to use them, and answer questions about what to connect to. Should an e3000 be connected to a hub, or to a switch? (Switch!) Does a printer need to be connected to a hub or a switch? (A hub will usually be fine.) Should I use my e3000 as a gateway? (I think not.) Should the physical part of my network the e3000 is on be bridged? (Yes.) Can I configure a gateway and connect my e3000 to the Internet? (Certainly. But make sure you have a firewall first!) Can I use other protocols or connections besides TCP/IP and Ethernet? (Absolutely! X.25, SNA, FDDI, and a number of other connections are available, but they change a lot, so check with your favorite sales rep first.)
So long as HP continues to
expand and extend the capabilities of their workhorse system, the
e3000 will continue to be the perfect business computer choice. As
everyone who uses and loves it knows stick with it and your
business just keeps flowing along, leaving your competitors all
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