Do managed switches decrease network performance between PC and router w/ 4-port built-in switch?

[sirhawkeye]

If i have a configuration such as this:

Router1 -> Managed Switch1-> Pc1, (and also Managed Switch1 -> Pc2, Managed Switch1 -> Pc3)

(Where PC1, PC2, and PC3 are connected to Managed Switch1 via gigabit network cables to each PC, and then from the Managed Switch1, which is connected to Router1 via a single gigabit eithernet CAT6 cable)


The same would be for (managed Switch2 and Managed Switch3). Each managed switch will have 3 PCs connected to it, and all managed switches go back to the router via one gigabit CAT6 cable.

Will the Managed Switches decrease the network bandwidth between Pc1, Pc2 and Router1?

I'm working on a home network installation, but have to use this set up as I'm unable to install a 24-port switch and run extra wires. Each room needs 2-3 ports, and was thinking of putting in 3 switches (on per room) which all link back to the Router's built-in 4 port switch.

I'm aware that there has to be some sort of decrease in speed but am not sure if that's a 50% or less decrease. I know with wireless networks and wireless repeaters, I've heard you can lose up to 50% of bandwidth with a repeated wireless signal using such devices.

What kind of decrease in bandwidth/network speed would I expect assuming all components are gigabit capable (wiring, switches, router, and network adapters)?

 

[anbu13]

NIC of all PC's, Ethernet ports of the Routers and Switches should be Gigabit Interface to utilize maximum throughput among the network. Wireless AP or repeaters also available in Gigabit speeds.
You may notice the decrease when transferring a file among PC's may not be upto Gigabit speed because the HDD's in the PC's should transfer the file less than Gigabit speed.
And the wiring should not be interfered by electrical wires, microwave etc. Switches should not be looped unless you use protocols for redundancy.

 

[bill001g]

For the most part you should assume there is no decrease because of a switch. A managed switch just adds more features it does not increase the delay. This is part of the reason a managed switch is more expensive than unmanaged. The switching is done with asic chips not actual cpu type processors. Asic that have more features cost more money but still do not delay the traffic.

Almost all switches you find now days run at what is called wire speed. This means the switch can send at 1g and receive at 1g on all the ports at the same time. There is no realistic case that can come even close to the total capacity of a switch.

Now if you really want to be anal about it every device does add a small delay since the data must be copied off the port into a buffer and then send from the buffer out the other port. Worst case would be 1500byte packets. So you multiple by 8 and divide by 1gbit to get the time.

 

[sirhawkeye]

OK that's sort of what I was thinking (well, actually I thought there might be a small bandwidth hit, like 10% (which is still fine for my application as the PCs connected to these switches are mainly going to be doing office tasks, general file transfers, and maybe some streaming of music and ripped videos, but nothing like full HD or anything like that that would demand a high level of bandwidth).

 

[anbu13]

Thats clear I didn't know about the delay.

Worst case would be 1500byte packets. So you multiple by 8 and divide by 1gbit to get the time.

Can you explain this? just did not understand this one. Could you give any example?

 

[bill001g]

Its simple math what do you want explained. The packet size of 1500bytes is just the maximum the average is much lower because of how data is send you see lots of minimum packets of 64bytes.

 

[sirhawkeye]

Thats clear I didn't know about the delay.

Worst case would be 1500byte packets. So you multiple by 8 and divide by 1gbit to get the time.

Can you explain this? just did not understand this one. Could you give any example?

He's referring to the number of packets (based on 1.5Kb sized packets) you could fit through in a 1Gb connection.

Basically, I've come to the determination that a few switches is not going to hurt performance (at least, noticably). In a large, commercial implementation a lot of switches might, but I'm only going to have 3 or 4, all connected to a home wireless router's built-in NIC ports.