Lessons learnt DMX over IP.. Part(1) there is standards / there is no standards

[mrpackethead]

Unicast gets about one sentence of discussion in the e1.31 standard. I personally like multicast a lot as it's generally plug and play. As long as the universe numbers match, everything (generally) talks.

Yes, using multicast is significantly easier than unicast thats fore sure.

For 99% of users it won't be an issue.

in 2008 we hadn't heard of the RGB pixel mega tree. In 2009 just another mega tree, in 2010, we installed some pretty large scale commercial shows, in 2011 we saw widespread deployment of pixels domestically.. THeres a trend, and in 2012 i think you'll start to see some pretty huge domestic installations who start to get scaling issues.

When I was doing some initial testing with the WIZ5100 chip, I found that I could do 6 universes of E1.31 by running the chip in raw mode and letting the cpu handle the packet inspection. But instead I decided to go with one universe per hardware socket. This limited me to 4 universes, but since the packet inspection is all done in hardware rather than having to be handled by the CPU, the presence of large numbers of packets on the LAN doesn't cause a problem. The WIZ5200 should be good for 8 universes. Everything is a tradeoff.

Eight universes in total on the wire?

[Barnabybear]

Not that i'm to up on them, but isn't that what subnets are for to avoid transmitting large amounts of data to devices that don't need to see it?

[mrpackethead]

In the old days when networks where built using 10base2 ( coax ) or you had 'hubs' rather than switches what you say would have been true.

In a switched network, the job of the switch is to make sure that as far as possible that only traffic destined for a 'device' ends up at a device. It does this by learning the mac-address's of all the devices, and which ports they are attached to. It matches the destination mac address of a packet against this 'table' and forwards it to the relevant port.

For unicast packets this is pretty straight forward. For multicast packets, things get more trickery...

[Barnabybear]

For unicast packets this is pretty straight forward. For multicast packets, things get more trickery..

How trickery? I've just finished building two E681s which currently don't support unicast (I don't know if there are any plans for it). These will be for a mega tree.
I'm sure that I will add more pixels as time goes on & I haven't bought any switches yet. So supposing that we get into the realms of 12 to 16 universes – did I ought to be looking for specific equipment and setup to avoid problems?

[mrpackethead]

@Barnabybear..

I'm sure that jstjohn will jump in, but i'm pretty sure that the E681 by default supports E1.31 over unicast. If it does then you just need to make sure that your media server does that as well. At the 12-16 universe space you'll be fine probably..

However if you want to do things in multicast, and your transmitting over that 8 universe limit that Jstjohn is talking bout then you'll need an ethernet switch which has IGMP snopping support. ( and the controller will need to have an IGMP client capability )..

[budude]

The E681 defaults (and only supports) multicast with the current code. Frankly if you're into the 10+ universe stage then another couple thousand for a good refurbed higher end switch is a blip... Do you really want to trust 30K+ worth of setup on $100 Best Buy special - no...

[mrpackethead]

The E681 defaults (and only supports) multicast with the current code. Frankly if you're into the 10+ universe stage then another couple thousand for a good refurbed higher end switch is a blip... Do you really want to trust 30K+ worth of setup on $100 Best Buy special - no...

Does the E681 support IGMP as well?

[dirknerkle]

The E681 defaults (and only supports) multicast with the current code. Frankly if you're into the 10+ universe stage then another couple thousand for a good refurbed higher end switch is a blip... Do you really want to trust 30K+ worth of setup on $100 Best Buy special - no...

I think cisco has some awesomely fast gear, and sometimes you can pick up a good factory refurb unit pretty reasonably...

[budude]

I think cisco has some awesomely fast gear, and sometimes you can pick up a good factory refurb unit pretty reasonably...

I've heard some people say that yeah...

[mrpackethead]

Been a while since Cisco had the fastest switches. Though they still have the best marketing machine.