Net3 and VLAN's

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TechZuul Posted: 07-31-2009 5:08 PM

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Our current setup:

Lighting Network:

EOS console, 4 Sensor CEM+ racks, 1 4-port DMX gateway, 1 Show Control Gateway, Net3 jacks around the theater, 2 10/100 switches for interconnections.

Audio Network 1:

Audio console (Yamaha M7CL), Audio Playback/Show Control PC (Stage Research SFX 6.0), 4 Audio Distribution Processors (DBX ZonePro), Administration PC (running manufacturer's software for devices), NAS drive for file backup/print server,  3 10/100 switches for interconnections

Audio Network 2:

Routes CobraNet from audio console to processor/amplifier racks

The Questions:

1 - Could these be combined into 1 network with VLAN's for segmentation? I am hoping to be able to make single points (i.e single PC's) of control and monitoring of all these ethernet devices. We would upgrade switches and backbone connections to gigabit ethernet or fiber to handle increased bandwidth.

2 - Should these be combined into 1 network? It works now but I am thinking combining would allow greater efficiency in management and monitoring.

Any thoughts/opinions are greatly appreciated..

Joel Howden

Theater Technician

Fullerton College

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tomsteer replied on 08-03-2009 9:31 AM

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As always with networking questions, the answer is "Yes you can, but...."

Combining systems onto VLANS comes with risks. As someone who has worked on several systems involving VLAN segregation of lighting data from other system data, I can tell you we usually have to spend considerable time proving what is at fault - the network or our equipment - when things don't work. VLANs add a layer of complexity that is often unwanted in entertainment systems.

The other issues would certainly be bandwidth (which can be addressed as you mentioned by switching critical links to gigabit/fibre), but the other important consideration for entertainment systems is latency. This is what makes entertainment systems a bit unique - if you're using a network for internet access, it doesn't matter if the odd request gets lost or delivered late - but that is very important when you're talking about a live sound feed or lighting fade. Larger, more complex network gear may, unless you take a lot of care in configuration, actually increase the latency of your network.

So, if it was down to me, I would say no - keep it simple, multiple networks are easier to troubleshoot (especially by folks with a non networking background), and it's clearer to the untrained eye what's going on. The single point of monitioring is a good question, the way we've addressed that in the past is just to use a multi-homed machine - install 2/3 network cards and you maintain the separation of the networks whilst being able to 'see' everything from a single point.

Hope that helps,

Tom

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dmclaughlin replied on 08-13-2009 9:31 AM

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I'll put on my IT hat, and second Tom with my own two cents and qualifications.  Please note, this may be more information than you wanted...

The amount of money you would spend on new networking gear and the time to program would most likely outweigh the benefit in this situation.  Plus unless you do have an IT professional on staff who is able to packet inspect the network, or you are such a person, its probably not a good idea.  A modern Layer 2 or 3 routed managed switch is really not a DIY project. 

With the low cost and relatively high efficiency of modern unmanaged switches, unless you have a really good reason to put this stuff on the same hardware, I wouldn't.

Having said that, here are some situations where this would merit consideration:

• Centralization and Redundancy - If your networks are all over the place in the building on different wire, on different power, and no one knows where any of it goes, or exactly where all the end points of each particular switch is, then maybe Centralization will be good for you.  Its pretty hard to troubleshoot something if you have no clear idea about how its tied together.  If doing this will bring everything back into one IT room/Dimmer Room, etc. than maybe this would be a good move.  Also if you in a situation where network failure would be catastrophic (I'm talking like lights in a casino..) then centralization allows you to put in redundant switches and power backup systems.  But remember, this is a two way street.  In the current configuration with everything separate, a problem with the hardware on the lighting network will not affect sound.  In a centralized system this is no longer true.
• Security - Again, on a system where security is important (ie casino networks) VLANing is an effective way of managing and segregating and monitoring traffic to prevent the compromise of one system affecting another.  This is almost never a concern in a lighting control network
• Logistics - In a facility that doesn't have room to add more switches and patch panels, VLANing is an effective way to expand.  Also there are sometimes that one swtich is much better than two.  We once had to engineer a control network for a bridge.  The master control station is a 1/4 mile away in another bridge over fiber.  To run the LEDs and the ETC gear we chose to use VLANs instead of multiple switches just because of the cost of fiber pulls and space considerations.

In all these situations it can be a pain to configure, espeically to maintain QoS (Quality of Service) that entertainment protocols require.

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JPALMERLD replied on 08-13-2009 11:55 AM

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You've gotten really good responses, but let me add my $.02.

1.)  You will connect my lighting network to the sound network over my dead body!  I have a pair of wire cutters and I know how to use them.

2.)  I have in troubleshooting and fixing lighting network problems had to reset the network switch.  If troubleshooting one part of the network  causes you to lose the rest of the network, a sound or lighting problem that the production team is working around has just become an unscheduled break for everyone possibly without worklights or houselights.

3.)  K  I  S  S

Take care,

John