8 port switch question

[thevikester]

Hypothetical (next year) I have filled up an 8 port switch, and upon additional expansion next year, was looking to add an additional switch(which I already have), without buying a 16 port switch.  IF, you have your Ethernet from the computer go to the first switch, and have 6 connections to controllers, and then one connection from the first switch go to another switch,...with additional connections from that switch to controllers...will that work? Or is there a risk of data lag/loss or would it just not work altogether... running unicast if that makes a difference.   Thanks

[k6ccc]

No problem at all.  Three of my four E1.31 boards are running through multiple switches.

 

For the year round landscape lighting, one of the E6804s is connected to the same switch that the show computer is connected to.  The other E6804 is connected to a switch in the front yard, which connects to a switch in the garage which connects to the family room switch that the show computer is plugged into.

 

For the two E682 that are Christmas only, they are both plugged into a 4 port switch in the attic which connects to the family room switch.  The attic switch was added this year because of the addition of the second E682 in the attic.  Only problem that I had was the original hub was old and crappy and was resulting in 5 - 15% ping failure on both E682s.  Replaced that with a switch I had laying around (actually a typical home WiFi router that was dumbed down to just playing switch with no router or WiFi capability), and then got over 16,000 pings with no fails to both E682s when I quit the pings and went to bed.

 

No, I admit I am not normal having four network switches in my house...

[thevikester]

Great! Thank you for the real world experience!

[Jeff Messer]

No problem here either Vikester. I have three switches hooked up in a row and working great. I will install number 4 in the shop to test from two locations this weekend.

[bob_moody]

I thought I would add that while yes you can cascade your switches, they will connect and they will pass traffic and for most occasions they work flawlessly... but you are injecting a potential issue for yourself as your show and data flow demands increase.

 

Even less expensive switches have an internal amount of bandwidth to work in reffered to as the switching fabric. This is generally much greater than any one port. Switching fabric can be upwards of several hundred MB or GB per sec depending on the switch.

 

So when you cascade a switch using Port to Port connections you create what could best be described as a multi-lane super highway, necked down to a 2 lane dirt road that opens back up to a super highway. Essentially, if something on the second switch needs a lot of bandwidth it will drop frames becasue the max usage is limited to the connection between the two switches.

 

IMHO.... we invest quite a bit into the these displays so I would inject the cost of a new switch into next years display.

 

Bob

[thevikester]

that is very good insight Bob thank you

[Max-Paul]

Although using this logic of a two lane dirt road. Dont you already have that situation with the cable from the computer to the first switch? I wonder what the amount of data is on a large display with lots of changes going on?

[bob_moody]

Although using this logic of a two lane dirt road. Dont you already have that situation with the cable from the computer to the first switch?

 

Yes.. as is the case with every end-device attached to a switch, but I was referring to cascading switches not end points. When you cascade a switch you basically turn the switch (at the interconnect port) into a hub and defeat the purpose of a switch.

 

Take a pair of 5 port-100MB switches. On Switch-A you have full duplex bandwidth (200MB/s) to every port. When you cascade, on switch B, you now have (not including the inerconnect port) 4 Ports - 800MB/s of bandwidth competing for 1 Port - 200MB/s of bandwidth to get back/forth to some source on Switch A. That was the point I was trying to make along with the much simpler, reducing points of failure.

 

However, to your inquiry, in our usage (environment), my concerns are probably moot.

 

1. The devices we attach are unidirectional (at least mine are) so there is only one way traffic(outbound). However, if I have say 3 devices on a cascaded switch, all the traffic (potentially 300MB/s (half duplex) ) is being funneled though the single 100MB/s (half duplex) connection between switches.

 

2. We dont have other devices on the network that other ports would be talking/listening to .. like storage, other computers etc; so network traffic and latency probably are not an issue we have to address (excluding the example from item 1).

 

Its also my intent that the discussion might help someone that is translating this information from thier Christmas display to thier SOHO network in resolving why when they cascaded a switch to accomodate thier new Netflix capable TV and Xbox One, the TV buffers and Xbox freezes in the middle of a game.

 

To the second part of your inquiry... I dont have the equipment to analyze the data stream so I wouldnt know. I can only assume that since all my devices (J1Sys D2's and P2's) have 100MB/s connections that the bandwidth needed is well within that limit since I dont see any issues when running the dislpay. The 4 port switch I had last year was only 10Mb/s and i showed no apparent data issues.

 

"Piker" Bob

Edited December 8, 2014 by bob_moody