Performance effect of attaching a hub to a router?

[TygGer]

I currently have a 4 port router connecting 3 computers to the net and each other. Say for instance, if I add another 4 port hub to the existing... what performance effects will I notice?

-the comps connected to the 2nd hub will be slower than the first comps while surfing the Internet?
-what about LAN performance?

Thanks!

 

[sabka]

You won't notice that much - use a switch instead if you're really worried about a little network-slowdown.
The bandwidth of an ethernet cable & switch combination should be above what your NIC card can practically put through anyways, so you should be fine.

 

[Tigger2k]

I have the setup you are describing and have not noticed any degradation in performance on any machine on the network.

Tigger2k

 

[JackMDS]

On a Network with less than 8 computers.

NONE.

 

[ScottMac]

Ditto Jack.

Hub, switch, no practical difference. Eight users, no difference in 99.99% of the cases.

FWIW

Scott

 

[TygGer]

Ok thanks.

At first, I was thinking of getting rid of the 4port and buying a new 8 port. Looks like I'll be saving some $$$ then.

 

[Fallen Kell]

Well... there is a difference, and its called total bandwidth available. But if all you are doing is just using the network to connect out to the internet as opposed to running major file serving/sharing on the internal network. Your bottle neck will still be the internet connection.

Basically think of it this way. The HUB will be shared bandwidth to all the systems connected to it. So roughly divide the bandwidth by the total number of computers on it. Now that is a rough idea, as you will also encounter problems like certain systems being more "talkative" then others and thus want to use the network all the time for no real reason, this will cause all the other systems on the HUB to slow down as they are forced to wait to communicate later.

You also need to take into effect that you also only have a 10/100 connection off the router itself. Basically even if you put another switch instead of a HUB, you would still loose some overall bandwitdh as a bottleneck would be created with connecting to the systems which are on the router itself (i.e. you have 100MB bandwidth total shared out off the new switch/hub, so only 100MB can be going through that line at any given time). If all the systems were on the same switch backplane, then the would have 100MB connection to each other, meaning that each system would have a full 100MB connection to any other system.

Like I said, I am being a little tough, as you probably are not using the network in this fashion. I just wanted to point out all the bottlenecks that this does cause so that you if you do wonder at some future time why you do not get a full 100MB connection to other systems that you don't blame things, when it is your network topology.

If you put all the computers on one switch you will have full bandwidth to each other system... so its up to you as to what you do.

 

[skyking]

The way to deal with those issues most of the time is to put the surfing machines on the hub, and any machines that you do big file transfers with on the switch. Most home networks have a few machines that really only surf.

 

[groovin]

ive thrown 16 users on the same hub and in day to day use like web and email, noticed almost difference whatsoever.

 

[ScottMac]

There is no such thing as a division of bandwidth. The system that is transmitting (or receiving, for that matter) is doing so at full bandwidth - always- .

There may be a slight delay while one machine waits for another machine to finish sending, but the delay is minimal. Also consider that most traffic is 512 bytes or less (mostly ~128-256bytes)... not much of a delay, if any.

The bandwidth advantage of a switch comes from the capability of maintaining multiple concurrent session, giveing the switch an apparent multiplication of bandwidth. If multiple devices are trying to access through the same port (like to a broadband Internet connection), then that connection is essentially shared, just like a hub, with no advantage.

A switch will also provide a full duplex connection - totally useless from a bandwidth perspective - , and a higher bandwidth - totally useless going to most broadband connections (~1.5m or so). All it means is that the data is buffered that much longer (higher latency on a busy/congested switch).

Businesses used to run upwards of dozens to hundreds of computers on a hub-based infrastructure; a couple of computers on a hub is nothing. The way most people use their switches, they may as well be hubs .... maybe even with better performance on the hub.

(and I'm already aware of the arguments, we've all been through this before, remain calm)

Just stirring things up .....

Scott

 

[skyking]

Not too stirred up for me
If a person had a need to push huge files between two boxes, then ideally one would want those boxes on the switched ports of the router, to save all that repeating to every other workstation. Beyond that application, a hub is just as good, from my observation also.
The average home LAN sees little or no tranfer between boxes anyway.

 

[Coldfusion]

While surfing the internet, you won't notice a difference.

As soon as you attach the hub and something to it, you'll start seeing collisions on your network. Depending on what you're doing, it may or may not be a noticeable degradation.

 

[TygGer]

Ok, so for surfing the Internet, we will only notice a degradation because of the limited bandwidth? But what about while gaming on the LAN? Will the computers attached to the second hub cause problems?

Thanks

 

[Fallen Kell]

Yes, they could experience problems. But they also could run just fine.

To Scott: The point I was trying to get across was that with a hub, it is shared bandwidth across all the machines. Yes, I totally understand that only 1 system can use the network at one time. That is exactly my point. ONLY 1 CAN USE THE NETWORK AT ONE TIME! In a gaming environment, as in LAN games, you can seriously expect to see multiple collisions occur on this network. With the price difference between a hub and a switch being what it is, it is really just worth it to get a switch at this point.

 

[skyking]

I have a friend I sold a 10baseT hub to, and he had upwards of 8 players in BF 1942, with zero problems. When someone can document some issues with gaming on a hub, I'll be happy to look at it. Gaming traffic is not that intensive, due to being engineered for usage across dialup connections.
You will notice no degredation with surfing on the hub, period. I would connect computers that I was transferring large files between, we are talking 100's of mb's files, to the switch ports.
I pick up used stuff on ebay and the like, and you can find hubs for almost free, if you know where to look.

 

[dnoyeb]

Originally posted by: ScottMac
There is no such thing as a division of bandwidth. The system that is transmitting (or receiving, for that matter) is doing so at full bandwidth - always- .

There may be a slight delay while one machine waits for another machine to finish sending, but the delay is minimal. Also consider that most traffic is 512 bytes or less (mostly ~128-256bytes)... not much of a delay, if any.

The bandwidth advantage of a switch comes from the capability of maintaining multiple concurrent session, giveing the switch an apparent multiplication of bandwidth. If multiple devices are trying to access through the same port (like to a broadband Internet connection), then that connection is essentially shared, just like a hub, with no advantage.

A switch will also provide a full duplex connection - totally useless from a bandwidth perspective - , and a higher bandwidth - totally useless going to most broadband connections (~1.5m or so). All it means is that the data is buffered that much longer (higher latency on a busy/congested switch).

Businesses used to run upwards of dozens to hundreds of computers on a hub-based infrastructure; a couple of computers on a hub is nothing. The way most people use their switches, they may as well be hubs .... maybe even with better performance on the hub.

(and I'm already aware of the arguments, we've all been through this before, remain calm)

Just stirring things up .....

Scott

You seem a bit pedantic. Their is no division of bandwidth with a HUB, but a switch can have multiple concurrent connections? sounds like 2 sides of the same coin.

Their is division of throughput which is what people usually mean when they say bandwidth. Yes, packets still move at the speed of light, from point to point But effectively the hub is most certainly sharing its bandwidth between all computers on it. 100Mb is the total that can pass through it, at any one time, period. Same with the switch. It can not pass 4 100Mb sessions at the same time AFAIK. Maybe some high end ISP level switches can do this.

The advantage of a switch is not in multiple sessions(unless you meant 1 sending and 1 receiving), but in specificity of connections. A hub reflects any data it receives on ALL of its connected nodes, but a switch only reflects the data on the target node.

For example, at work I can tell my computer is plugged into a Hub because the data light on my network card keeps flashing, but I am not sending/receiving any data(technically I am receiving). A switch wouldn't do that.


The hub will be just fine.

 

[ScottMac]

"Apparent multiplication of bandwidth" = multiple pairs of systems, using multiple pairs of ports, can communicate at the same time ... several logical circuits, as if they were connected directly together (each of the pair in session with the other member of the pair). Each of those pairs are communicating at full speed/bandwidth.

As soon as more than one system attempts to communicate to the same port (whether there is one system attached to that port, or if it's a "gateway" out (like to a cable modem), then that single port is shared bandwidth ... just like a hub ... except the buffering that the switch does to handle contention adds latency to the traffic. Since a system connected to a hub cannot transmit until it senses the line is clear, there is no latency and no chance whatsoever that the packet(s) will time-out in the hub, or due to latency induced by the hub (which is negligible to the point of being null).

Switches will flood all traffic out all ports for a broadcast (just like a hub), multicast (just like a hub), or if it doesn't recognize the MAC of the destination system (hubs don't care).

Switches still have to wait for a clear line (just like a hub); it's part of the Ethernet spec. Lots of broadcasts, multicasts, or unknown MACs will cause the same delay in a switch that it will in a hub. Even if the switch is configured for full duplex, the broadcasts, multicasts, or flooding will add to the latency of traffic behind it (buffered behind the BC, MC, or flood traffic).

The bandwidth of a hub is shared only in that a station must wait for a clear line to begin transmitting. On the rare occasion when two stations talk at the same time, they'll fall back and try again. No big deal in the grand scheme of things. When the stations do talk, they'll talk at full bandwidth supported by the hub; other stations will wait till they hear the line is clear, then the next station will transmit at full bandwidth.

For a couple stations, operating properly, with common applications (including many/most games), there will be no performance difference between a hub and a switch of similar configuration ... except the hub will have slightly less latency. There are, as one would expect, several "official" definitions of latency; in the case of a hub none of the "official" definitions of latency make any difference (the variance of definitions are usually applied to cut-through versus store-and-forward to make that particular vendor's stats look better).

Certainly, a switch properly implemented can offer some advantages. They way most people talk about using switches, they could just as easily use a hub and see the same performance.

Now I gotta go look up the definition of "Pendantic" ....

OH, and BTW: the traffic moves at ~66% the speed of light on UTP, even through most fiber optic. Check out "velocity factor" of the cabling.

Seeya

Scott

 

[Abzstrak]

just skip this crap. buy a 8 port or more switch and only uplink one line to the 4 port router and nothing else to the router. Attach everyone only to the new switch and you'll effectively run like a 8 port switch/router... plus a cheap 8 port switch is about $25.

Also, Scottmac knows his stuff, its smart to listen and learn from him ;-)

Dnoyeb, a switch CAN maintain concurrent 100Mbps sessions...for example, you can have 100Mbps full duplex going between ports 4 and 7, while also having a full 100Mbps connection between ports 23 and 14, and so on....the limit of these speeds depends on the backplane speeds, many switches of a fabric of 15Gbps or more, but only 24 10/100 ports.