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Author Topic: Dante and Spanning Tree running on redundant networks  (Read 1081 times)

Riley Casey

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Re: Dante and Spanning Tree running on redundant networks
« Reply #10 on: May 15, 2021, 12:04:46 pm »

I'm not qualified to address the hardcore nuts and bolts of networking but it never hurts to remember that the initial design criteria for Dante redundancy was addressing the portable /  tour market where snakes routinely unspooled daily and essentially ran thru open top conduit or sometimes literally under the feet of thousands of audience members. A Dante network installed in a venue with cables permanently installed in EMT and with connectors that might be re-mated once a year is pretty robust to start with. Its certainly is a good idea to have back up everything and redundancy is only a bad thing when it leads to misconfiguration but it doesn't need to be a religion.


I'm standing up redundant Dante networks for a performing arts center.  ...

Helge A Bentsen

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Re: Dante and Spanning Tree running on redundant networks
« Reply #11 on: May 15, 2021, 01:58:30 pm »

I'm not qualified to address the hardcore nuts and bolts of networking but it never hurts to remember that the initial design criteria for Dante redundancy was addressing the portable /  tour market where snakes routinely unspooled daily and essentially ran thru open top conduit or sometimes literally under the feet of thousands of audience members. A Dante network installed in a venue with cables permanently installed in EMT and with connectors that might be re-mated once a year is pretty robust to start with. Its certainly is a good idea to have back up everything and redundancy is only a bad thing when it leads to misconfiguration but it doesn't need to be a religion.

Agreed.
I frequently run  Dante primary only, no issues.
But, if my cables are exposed to traffic or other mechanical issues, I run secondary as well.
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brian maddox

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Re: Dante and Spanning Tree running on redundant networks
« Reply #12 on: May 15, 2021, 04:34:17 pm »

Agreed.
I frequently run  Dante primary only, no issues.
But, if my cables are exposed to traffic or other mechanical issues, I run secondary as well.

At the risk of swerving the thread...

I've come to pick and choose very carefully where I run a secondary network for Dante and where I don't. The reason for this is that running a secondary network into any device enables cabling redundancy BUT also introduces a potential catastrophic failure point as well because as soon as they are in the same physical box, the potential for them to be "merged" into a single network and crash your entire Dante system becomes at least a possibility. A number of Dante devices, when initialized, revert to "daisy chain" mode. This is catastrophic and will crash your entire Dante network, often requiring a complete reboot of EVERY device on the network including ALL of your switches. I've had this happen with a Shure wireless unit [completely on it's own mind you]. I've had this happen with a Yamaha RIO [during troubleshooting another issue, but still a major PITA]. This is not a failure you want to have happen during a show.

This is also why I cringe when single switches are configured for separate VLans and the Primary and Secondary are run on the same switch. Yes, it should work fine. But if it should STOP "working fine" [due to someone fat fingering a switch configuration change or any number of other potential oopses] it's gonna be a Pretty Big Deal.

I heard recently that even NASA has admitted that overly obsessing over too many Fail Over redundant systems can, in and of itself, lead to failures. Just something to keep in mind.
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brian maddox
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Phillip Ivan Pietruschka

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Re: Dante and Spanning Tree running on redundant networks
« Reply #13 on: May 15, 2021, 08:16:53 pm »

Brian,

The Dante engineer I did L3 training with a few years ago was very strongly of the opinion that redundancy was principally of value for live production work where there was an appreciable risk of cables being damaged or the like. For installs where this isnít a plausible risk, and higher end switches are used he argued there was basically no point, or the cost & risk V benefit was marginal. It does make sense in broadcast and other facilities which require 24Hr uptime; and without that redundancy maintenance becomes fraught. Iíve heard similar sentiments discussed by broadcast engineers talking about 2110 installations.
« Last Edit: May 15, 2021, 10:39:24 pm by Phillip Ivan Pietruschka »
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Erik Jerde

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Re: Dante and Spanning Tree running on redundant networks
« Reply #14 on: May 16, 2021, 10:31:14 am »

So reading through this I think there may be a couple of mis-understandings from the OPs original.  It reads to me like some people think the IT recommendation is to have the primary and secondary networks as part of the same ring.  I believe that is incorrect and that the recommendation is still two separate primary and secondary networks with the switches daisy chained and the last switch in the chain linked back to the first.  STP would then kill one of the links and you'd have your tree.

Regarding the STP election, unless STP is completely eliminated there will always be an election when another switch is plugged in, ring or not.  So when that portable rack is connected and starts sending out it's BPDUs that will trigger an election ring or no.

I personally am loathe to disable STP because I don't trust people to plug stuff in correctly.  I've had to deal with production networks getting interconnected to office networks resulting in dueling DHCP servers and the resulting chaos because a construction worker thought he was helping.  That one was hard to track down because it was stuffed up in a ceiling.  I've never had STP problems because I always leave it enabled.

I would expect that a STP election wouldn't interrupt dante where there is a primary/secondary system setup.  Of course there's lots of primary only devices that could be taken out.  It should be easy to test what actually happens.

You could leave STP enabled on the main switches but disable it on all ports that are permanently plugged in to wall plates.  I'd still be cautious when there's multiple ports present right next to each other.  End users have a way of screwing things up and I could still see people plugging one switch into two ports.  If you had STP off on those ports then your network would get hammered worse than a STP election would do.

As to the ring design vis-a-vis dante, I'd skip that regardless of STP because it makes the network too deep.  IT needs to be instructed that the network should remain as flat as possible.  If redundancy is desired on the switch interconnects look into LAG groups.  I'm not aware of them being contra indicated for Dante though it's entirely possible I've missed that.
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Russell Ault

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Re: Dante and Spanning Tree running on redundant networks
« Reply #15 on: May 16, 2021, 04:05:24 pm »

{...} I personally am loathe to disable STP because I don't trust people to plug stuff in correctly.  I've had to deal with production networks getting interconnected to office networks resulting in dueling DHCP servers and the resulting chaos because a construction worker thought he was helping.  That one was hard to track down because it was stuffed up in a ceiling.  I've never had STP problems because I always leave it enabled. {...}

Huh, this is exactly the opposite of common practice here. All of the PACs I work at (several of which are even municipally-owned) have production networks that are so air-gapped from the rest of the building that the in-house IT department doesn't even know they exist. Heck, in at least one venue, the production networks are so air-gapped that other departments don't even know they exist (jokes about the nature of the stage carpenters' network are left as an exercise for the reader). Production network ports are only provided in locations where anyone who has access to them can be subjected to termination (or, at a minimum, buying everyone a round) should a show-stopping mistake occur, at which point I'd personally rather troubleshoot a broadcast storm (i.e. a persistent failure) than an STP election interruption (i.e. an intermittent failure).

For the OP, the other thing to remember with Dante and adding switches is that so many (almost all?) two-port Dante devices can also act as switches in some configurations, so it's possible to plug in something as simple as a single microphone RX and trigger an election.

-Russ
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brian maddox

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Re: Dante and Spanning Tree running on redundant networks
« Reply #16 on: May 16, 2021, 07:42:22 pm »

....
For the OP, the other thing to remember with Dante and adding switches is that so many (almost all?) two-port Dante devices can also act as switches in some configurations, so it's possible to plug in something as simple as a single microphone RX and trigger an election.

-Russ

You said what I said, but much more betterer. :)
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Re: Dante and Spanning Tree running on redundant networks
¬ę Reply #16 on: May 16, 2021, 07:42:22 pm ¬Ľ


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