[G4] Router definition and Ethernet Broadband question.

[Philip J Robar]

On Dec 13, 2005, at 7:18 AM, Alex Hurst wrote:

> Tony wrote in part:
>
>> Its all beside the point, a router can be a good thing in  
>> protecting oneself
>> from the evils of the internet.
>
> Forgive my ignorance, but is a router the same thing as a hub?
>
> [snip]

No. Keeping things simple. A hub connections several wires together  
to form a network. Packets are distributed to all ports on the hub  
regardless of which port the machine the packets are actually  
addressed to is actually hooked up to. Unmanaged switches are like  
hubs except they only send data out the port that the machine they  
are addressed to is hooked up to. This reduces the amount of traffic  
on any given segment of the network, which allows for higher  
performance. Even simple unmanaged switches used to be much more  
expensive than hubs. Although it's unlikely to make any difference on  
a home network unmanaged switches are now so inexpensive that it  
doesn't make any sense to buy a hub.

The addresses that switches use to direct data to the correct port  
are associated with the physical network connection on each machine.  
They are called ethernet or more properly MAC (media access control)  
addresses. These address are what ultimately provide each computer  
with a unique identity on a network.

Routers on the other hand are used to direct packets between  
networks, e.g. between your home network and the Internet (or more  
specifically your ISP's network), using higher level IP (internet  
protocol) addresses. IP addresses are explicitly not permanently tied  
to a specific computer so that the computer associated with that  
address can be changed without others having to being aware of the  
change.

Home routers commonly include a small switch,  know how to talk to a  
cable or DSL modem, and also provide NAT (network address  
translation) and DHCP (dynamic host configuration Protocol) services.  
NAT allows all the machines on a network to share the, usually,  
single public address that an ISP assigns to a customer. In addition  
NAT, combined with the use of private IP address, protects your local  
network in a couple of ways. Private addresses are a range of IP  
address that everyone has formally agreed not to route over the  
public Internet. This means that information traveling from one  
computer to another on your local network can not leak out of your  
network. Secondly, since the private addresses are only visible to  
your network, no one outside of your network knows about or can  
access your computers unless you specifically set up a relation  
between your public address, a specific service, and a machine on  
your local network.

DHCP is a convenience that centralizes the assignment of network  
personalities to computers on a network rather than having to  
individually configure each machine. Basically with DHCP when a  
computer wakes up it asks the network "who am I" and the DHCP server  
responds with the information needed for the computer to configure  
it's network presence.


> As I have a Netgear Ethernet hub which links my G4 to two G3 Macs  
> with no problem, am I right in assuming that I just plug the  
> broadband modem connection into any free socket?

No. While you could make this arrangement work by adding a second  
network interface to one of your computers and setting up internet  
connection sharing, home routers are now so inexpensive that it's far  
more trouble than it's worth. You should get a home router as  
described above. Home routers are cheap, you can get one for $0 to a  
few $10's of dollars depending on how hard you look and how you feel  
about rebates.

Also, while many vendors advertise their NAT feature as a firewall,  
and NAT does indeed provide all the protection that most people need,  
I'd advise that you get a router that provides an SPI (statefull  
packet inspection) firewall. SPI used to be found only in expensive  
firewall products, but it is now quite common even in inexpensive  
home routers.

You might also consider getting a wireless router in anticipation of  
future needs, especially since they can often be purchased for the  
same price as a non-wireless router.

Another router feature that is poised to become important is QOS  
(quality of service) which allows a router to prioritize the flow of  
time sensitive information such as VOIP (voice, i.e. telephone, over  
IP), streaming video and audio, and gaming.

  I recently purchased a wireless router with all of the features  
mentioned above and more for $30.

>  I seem to remember the hub has one socket that's slightly  
> different from the others in function, but it didn't come with an  
> instruction book.

That port is used to hook up one hub/switch to another with out the  
use of a special cable so as to be able to expand the size of your  
network.


Phil
--
"I distrust those people who know so well what God wants them to do  
because I notice it always coincides with their own desires." --  
Susan B. Anthony