Daisy-Chain Gigabit Switches

[BassKozz]

Is there a problem with Daisy-Chaining gigabit switches?

I know ideally I should have just one gigabit switch with many ports, but I've (over time) stocked up on Gigabit switches specifically the 5 port kind... so I was wondering if it's a problem to daisy-chain them?

Right now I've got 3x 5 port Gigabit switches connected to my router (which is only 10/100), so the devices that are connected to each switch can communicate at gigabit speeds but once it goes thru the router its back to 100Mb/s, so could I daisy-chain them like so:

(WAN/Internet) Router -> gigabit -> gigabit -> gigabit ?
How much would this affect the last switch's devices as far as it's connection to WAN because it's 2 switches away from the router.

Any/All Comments/incite are much appreciated.
-BassKozz

 

[Zepher]

That is how our network at home is setup and it works great.
Router to HP4500DN, Downstairs PC, and then to a line going upstairs to a GigE switch.
From that switch it goes to my Main PC, my HTPC, to a 10/100 switch (for Xbox and an extra hookup when setting up PC's), and then to another GigE switch.
That GigE switch is connected to 2 PC's and 1 Server and also hooks up to a 10/100 switch for an Xbox in that room as well..

 

[CaseyBlackburn]

You will only run into an issue if you have three clients on the last gigabit switch transferring to the first gigabit switch. All three will be sharing a single gigabit port, so you may experience a decrease in speed, other than that, I see no issue.

 

[xphil3]

You will only run into an issue if you have three clients on the last gigabit switch transferring to the first gigabit switch. All three will be sharing a single gigabit port, so you may experience a decrease in speed, other than that, I see no issue.

what casey said, technically speaking you are oversubscribing your ports by 1 each time you add a device behind the one uplink. So if you only have one uplink from your switch to another any host on edge or access switch will only have 1Gbps shared throughput. I can only see an issues if you start oversubscribing ~10:1 and move heavy amounts of traffic from all your hosts.

 

[BassKozz]

what casey said, technically speaking you are oversubscribing your ports by 1 each time you add a device behind the one uplink. So if you only have one uplink from your switch to another any host on edge or access switch will only have 1Gbps shared throughput. I can only see an issues if you start oversubscribing ~10:1 and move heavy amounts of traffic from all your hosts.

Thanks for the input xphil3, you mind expanding on this, I am confused about "any host on edge or access switch will only have 1Gbps shared throughput" and the "~10:1" ratio

 

[hokatichenci]

Direct daisy chaining should not cause any problems, except for the already mentioned bandwidth subscription issues. If you have a circular "route" ie, 4 switches marked A/B/C/D:
A<->B
B<->C
C<->D
D<->A

with cheap hardware you would probably experience various issues. So long as you keep all the cabling straight you should be fine.

 

[CaseyBlackburn]

Thanks for the input xphil3, you mind expanding on this, I am confused about "any host on edge or access switch will only have 1Gbps shared throughput" and the "~10:1" ratio

What we are saying is that a whole switch has to share a single port on another switch so that switch is limited to only 1Gbps of total traffic to another switch, so all 4 clients have to share a single 1Gbps when contacting another switch. The ~10:1 ratio was he was saying that what is mentioned above won't be that big of a problem, it just starts to become a problem when about 10 or more clients are sharing that 1Gbps of throughput.

 

[Madwand]

You might rearrange them to reduce depth.

E.g.: router <-> Gb-A <-> {Gb-B, Gb-C}

 

[TechLarry]

This is a good point, and one of the reasons I cleared out all my switches and went with a single, 16-port DLink DGS-1216T Smartswitch. Cost $225 but it's probably the last one I'll ever have to buy.

You will only run into an issue if you have three clients on the last gigabit switch transferring to the first gigabit switch. All three will be sharing a single gigabit port, so you may experience a decrease in speed, other than that, I see no issue.

 

[BassKozz]

Great, now I get it.

I only have 1 more question on the topic, does the last switch in the chain experience any sort of latency (and/or worse, packetloss, etc) sending/receiving to/from the router (internet/wan), because it's the last in line?
Or is the latency negligible?

Thanks for all the help.

 

[Madwand]

If you have three clients communicating with one server over gigabit, it's not really going to matter how the switches are connected.

1. The server's probably not even going to be able to saturate a single gigabit connection.
2. If not (1), the server's still going to be limited by its own gigabit connection.
3. Even if not (2), and you have a trunked multi-port connection to the server, it's not likely to be able to do much more than 1 Gb/s.
4. Even if not (3), it's still not very common to have multi-gigabit utilizing transfers running concurrently in home networks.

Bottom line is that yes, it's possible to run a home network such that multiple gigabit links are being heavily utilized concurrently, but it's not very likely to occur frequently, so the switch setup generally doesn't really matter.

Reality > theory, so if anyone has a home network scenario which they actually use often and uses multiple gigabit links running at say > 500 Mb/s speed, I'd like to hear about it.

Of course whatever the OP does with his network matters most to him, and so far he's only expressed a concern about the link to the main router / Internet. As this typically runs much less than even 100 Mb/s, the answer "it doesn't really matter" might easily hold.

 

[RoBo]

I only have 1 more question on the topic, does the last switch in the chain experience any sort of latency (and/or worse, packetloss, etc)

Latency is minimal and there should be no packet loss.

 

[BassKozz]

Great, Thanks for all the input.