[pawstats-pats]

hi all,

i have read lots of web pages that explain how switches and hubs work but i couldnt find one that addresses my question: if you have a hub or switch connected to a router, is everything behind the hub or switch on the same network as everything else thats connected to the same router?

for example, i have verizon fios broadband, which came with its own verizon router.

due to the existing wiring of the house, what i would like to do is run two wires from the broadband router:

- a first one which will go into the Tivo Box that sits next to the router
- a second one which will go to the basement where it will be hooked up to an ethernet hub or switch.

my question is whether any further connections made into the ethernet hub from the second connection will be able to see directly over the network the tivo box thats sits on the first connection and is connected directly to the router. if my PC is connected to the ethernet hub will it be on the same network as the tivo box which is connected to the router? apparently thats the only way to guarantee that the tivo software will work.

more generally, if i want to split my internet connection so that i can connect many different devices, but i want all the devices to stay on the same network, which is the best piece of equipment that will allow me to do so, hubs or switch?

tia!
paw

[dlsayremn]

Everything will still be on the same subnet. All IP Addresses will be assigned by the router.

Switched networks are usually faster than HUB networks.

A hub basically sends all data to ever computer. The computers ethernet cards have to listen to all traffic and select only that addressed to it. Causes the cards to operate in half-duplex mode. Cannot transmit when receiving.

A switch on the other hand, only "routes" the data to the specific IP address involved. This allows the ethernet cards to run in full-duplex mode, can transmit and receive at the same time,

[pawstats-pats]

thank you very much thats very helpful!

will it be possible to add a second switch behind the first switch and still have everyone on the same subnet? if so, will doing so slow things down behind the 2nd switch?

[zx10guy]

In general, everything said by dlsayremn is correct. But things get more "fuzzy" if you get into higher level layer 2 networking. Which is what you are talking about here....layer 2 networking.

To clarify, the "routing" a switch does is better described as frame forwarding. A switch has memory called a MAC table which it associates a given MAC to a given switch port. This why switches provide better network performance over hubs. The IP addresses are not kept at the switch (except for more powerful and expensive managed switches.) Each computer has what is called an ARP table which it uses to translate IP addresses to MAC addresses. Every NIC has a unique MAC address which consists of hexadecimal numbers.

So that's a quick and dirty discussion of layer 2 networking and I've probably left a lot of details out as layer 2 networking can grow to a prolonged discussion.

When wiring two switches together also known as cascading or uplinking, you have to do some planning. Switched traffic is ALWAYS fastest if the traffic stays within the switch. The reason being is that each switch has what's called a back plane which has a set bandwidth which will always be greater than the switch ports on the switch. If you have to use multiple switches to extend out layer 2 connectivity, it is best to design the connections in such a way to keep all devices which will push a lot of data across the network on the same switch. If you have more than one device communicating at the maximum wire speed of each network port, you bottle neck will now be the SINGLE cable connection you have between switches. With streaming video and file sharing, it is really easy to saturate this link. The fix for this as I stated previously is to keep high bandwidth using devices co-located on the same switch. If this isn't possible, you have to step into managed switches which will allow you to group individual ports together as a single virtual connection between switches. Of all the switches I've seen, the max is 8 physical connections can be grouped under one virtual pipe. Another alternative which you don't see much on unmanaged GigE switches is the implementation of high speed uplink ports. Some unmanaged 100Mb switches include a single or a couple of GigE uplink ports meant to connect up to other switches. Being that the GigE uplink is much faster than the 100 Mb ports being used by regular hosts, you can get some assurance this uplink won't be as much of a bottle neck. The problem with unmanaged GigE switches is that for them to have a faster uplink port, you are looking at 10Gb ports which are extremely expensive to implement.