Subscriber Discussion

How To Avoid Downtime From PoE Switches?

UI
Undisclosed Integrator #1
Jan 20, 2017

It seems easy for the other components of the video system to have redundancy via either clustering, or virtualization. However, the vulnerability that I'm curious about is the PoE switch that has all the cameras connected to it providing it power and data. If that switch goes out, essentially all the cameras are down.

I've been thinking of splitting half the cameras on one PoE switch, and half on another PoE switch so at least if one goes down, we have some video. Is there a better solution?

UI
Undisclosed Integrator #4
Jan 20, 2017

Interesting question. I would suggest that unless the edge device has 2 LAN ports, then you could use edge storage with external power via fig8?

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UM
Undisclosed Manufacturer #2
Jan 20, 2017

Are you concerned about the switch PoE going out or the network switch portion going out?  If you are concerned about the power, you could loop through a PoE injector.  The injector would usually take priority, but if it were to fail, the PoE switch would pick up the power.

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MM
Michael Miller
Jan 20, 2017

Why not use a enterprise POE switch with with multiple power supplies. 

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Brian Karas
Jan 20, 2017
IPVM

But then what about downtime from the cabling? There was a discussion about dual-NIC cameras previously that had some interesting comments.

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Kevin Bennett
Jan 20, 2017

Enterprise class switches with redundant power supplies that have each supply plugged into a separate UPC is one method to ensure some level of continuity.  The UPCs should be enterprise class as well if this is a critical operation.

Depending on the environment your switch is operating in, you may want to consider environmentally hardened (aka "hardened" or "industrial") switches that can better tolerate extremes in temperatures.

And, as you suggested, spreading the load across multiple switches can help protect against a single point of failure.

If you are thinking about going the route that UM2 above - using PoE injectors and having a PoE switch as a backup in case the injectors fail, be sure the injectors will pass PoE (and data for that matter) from another source when the injector is offline.

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Mike Dotson
Jan 20, 2017
Formerly of Seneca • IPVMU Certified

If I may ask an educational question...

What are the primary failure mechanisms of POE Switches (and Midspans) seen out in the field?

Based on what was asked here, it appears to be the power supply.

Also, is there a fail case where a single POE port has an issue and needs to be recycled?

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MI
Matt Ion
Jan 20, 2017

I think I've had all of two mid- to upper-grade PoE switches fail on me, out of several dozen in use - one D-Link, one Cisco, both older units. The Cisco would sometimes lose connectivity on several ports (up to half of them) but get it back with a power cycle. The D-Link didn't fail in operation, but if it was power cycled, it would sometimes fail to start up properly.

I have a wide range of PoE switches in service right now, from 4+4 nameless unmanaged desktop switches to 48-port Cisco SGE models, all chunking away happily. There are even a bunch of old Linksys SFE-1000Ps (the first managed switches we used) still in service after 8+ years.

There are a lot of suggestions here of redundancies and backups and splitting up networks and whatnot, but basic risk assessment from MY experience is that switch failure is really not that much of a concern. We have gone with two 24-port models vs. a single 48-port on a couple sites for exactly this reason (so we don't lose ALL cameras if a switch fails) but five years on for this site, there hasn't been a single issue (the site also has another 24-port and an 8-port in remote locations).

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Jon Dillabaugh
Jan 23, 2017
Pro Focus LLC

Why not have 2x48 port switches with half of the 48 cams on each, with the ability to quickly patch the others over from a failed switch. At least that way you only have the downtime equivalent to the time it takes to patch over 24 cams. 

I see this as better than two fully loaded 24 port switches that don't offer any quick fixes if one fails. 

You could also argue that half loading 48 port switches may alleviate the issue of PSU failure, since they will likely be running at half load anyways. 

MM
Michael Miller
Jan 20, 2017

We have a lot of switches in the field and the only failures we have had where the cheap non-managed or 8+ year old Linksys switches.  We mostly us Hp 2920 switches which have hot-swappable power supplies and redundant power supply options.   These have been rock solid for us even ones that are installed in sealed NEMA boxes with direct sunlight on them (not my design)

Our health care and ISP customers would be the best ones to ask as downtime can cost a lot of money or worse kill someone.  They both use high-end Cisco gear with stacked switches, redundant power supply, and fiber rings.  If you want to build a switch network with max uptime I would follow what the big boys do. 

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MI
Matt Ion
Jan 22, 2017

Obviously those are more critical situations than a bank of cameras going offline in a retail or food establishment. As with most of this business, it's risk management vs. cost.

The restaurants are using mainly higher-end HP and Cisco models for their networks, because it can cost them a lot if their ordering and POS systems go down in the middle of a lunch rush. The cameras are important, but not OMG YOU HAVE TO GET THIS WORKING IN FIVE MINUTES OR WE'RE ALL DEAD important :)

UI
Undisclosed Integrator #1
Jan 23, 2017

Yeah I think going with some enterprise switches with redundant power supplies should be sufficient for our network. 

External power supplies was an interesting idea. Will keep that in mind. 

UM
Undisclosed Manufacturer #3
Jan 23, 2017

Using cameras support edge recording, add 24V power to cameras and using VMS support edge recording.

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