Net3 and VLAN's

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

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.

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

I have a slightly different VLAN questions, and while I hate to revive an older post, the data so far seems pertinent.  I work in a university setting, so getting permission to establish a wireless network is difficult at best.  When/if we get permission, we will at most get allocated one channel.  I need to establish wireless control for both audio and lighting, however the wireless will be non mission critical. 

What I am considering is this, a wireless network with multiple ssid's one for audio and one for lighting, each with their own vlan tag that could then be split at a smart switch, with one connection to the audio network and one to the lighting network.  I have a reasonable amount of network experience, but none with vlans...  I think, this method could/would prevent too much traffic on the mission critical portions of the network, with the only possibility being the wireless may have some latency issues

Thoughts?  Given the above advice is the foolish?

Thanks

Well, here is what comes off the top of my head.

It will probably work, with some caveats.

• You will most certainly have some latency issues.  Probably more noticeable with sound.
• The VLAN problem is largely one of protocol, not amount of traffic.  I wouldn't be concerned about the wireless putting too much traffic on the mission critical portions of the network, wire will always win on that one.
• Where VLANs will come to haunt you is in the management.  VLANs are largely transparent to the individual networks, provided that configure the trunking and management correctly.  You will need at minimum 3 VLANs (lx, sound, and management).  The trick here is to create a VLAN just for switch configuration, and to never let either the sound network or the lx network see any of the management traffic.  The other trick is getting the trunking configuration correct.  As you will be passing multiple VLANs from one device, the WAP down to another, the switch.  You will then establish port level VLANs for everything else.  So when considering a switch, you'll need one that allows you to actually configure VLANs on the port level, and configure their trunking operation.  A simple "smart switch" that just allows simple assignment of a VLAN to a port, or making a trunk port will probably not do. What does this mean?  A true Layer 2 managed switch - $$$.  You may be able to get by with one of those business class value smart switches, but I doubt they would be very reliable in function.

In the end its hard to judge if this is foolish or not.  If you need the functionality, and these are the constraints you must live in, then there are few options.  I can say this will probably cost more money than you originally thinking of spending.  As I would put around $500 minimum into an enterprise class managed switch (something that is not advertised as web managed - I'm thinking an HP ProCurve 2610).

Beyond this you will also have the classic multicast and IGMP problems to deal with when configuring a lighting network.  I'm sure there is also some specific compatibility issues to deal with in sound as well.  Plus once you link the two networks with this switch, realize that it has the high possibility of introducing problems into both networks independently.  Adding this one device means both systems are no longer vanilla networks.

One other thought - what kind of wireless control of the lighting do you need?  Would an RFR do the job?  Then you are back to one wireless network, and a lot less headaches.

I have run across this wireless situation before.  If there is fear of stepping on critical wireless communications then it is best to get permission.  I.E.  Live Broadcast.  With that being said.  There are many tools including tools provided on most wireless routers that can allow you to be stealth about adding wireless, and being secure.  With that said, if your IT department is concerned with you adding wireless networking devices to an isolated network, there are people at ETC that are more than willing to provide you with the information needed to calm your IT departments mind.  Feel free to give us a call.  800.688.4116.

cwaddell said:

When/if we get permission, we will at most get allocated one channel.  I need to establish wireless control for both audio and lighting, however the wireless will be non mission critical.

If you're told "You may transmit on this specific channel only", then I would suggest two physical wifi access points, one on each network, both set to that channel.

WiFi is designed to handle the idea that multiple access points may be transmitting on the same radio channel, so while it may slightly increase the latency of the wireless link (though probably not noticeably), it will be much easier to both fault-find and configure. (Plus you can use much cheaper hardware.)

- Eg Lighting wifi isn't working but the Audio one is. With two physical access points, the fault lies in the Lighting AP. With one access point trunked into two VLANs, it gets harder to figure out - maybe somebody reset the switch config you built? Maybe somebody linked the two VLANs together by accident and the Audio stream is now squashing Lighting?

However, if they mean that you're only allowed one Access Point, then you will have to use VLANs. (and *much* more expensive network kit)

The traffic on the two 'wired' networks would be the same either way:

• In the case of two VLANs, the additional VLAN header data only exists from the point of plugging into the managed switch to the WiFi transmission. Outside of that segment, the two sets of network hardware do not know about the existence of the other.
• In the case of two access points, there's no link between them at all, so the same result.

On a semi-related note, it's worth looking to see if you can do some filtering of the data going to the wireless link. It may be useful to prevent some kinds of data from going over the WiFi, while allowing the use of the relevent remotes.
- ArtNet in particular is well-known to become a problem when sent over WiFi as it tends to flood wireless links.

I suppose another Idea that I could pursue is to do this on the 5ghz band.  We only have to work with the college when we need a device in the 2.4 ghz band... then I could put audio on 2.4 ghz (or not, their problem...) and lighting on 5ghz...  I'm well aware of the issues with 5ghz and line of sight, but we can put the AP on our balcony rail.... that might be the easiest solution out there too....