When is managed E-net switch required

Hello all. I am at a place that swears by managed ethernet switches because their sales rep convinced them that's what they needed. Not having enough knowledge under my belt about using managed switches, I turn to you guys, please. If someone could share with me some instances where using a managed switch was a requirement please. I get the security part of it, that isn't the case here. There are probably 20 CLX and even more Flex IO all connected to the same network, so there is a lot of traffic however, I have seen systems more extended than this, operate just fine using regular ethernet switches/hubs. Would appreciate any and all info you could share with me. Thank you

In my (very limited) experience, a managed switch was only required when:
1. Forwarding ports
2. Ring redundancy
3. Duplicating ports


I am sure there are more reasons..

https://community.fs.com/blog/managed-vs-unmanaged-switch-which-one-can-satisfy-your-real-need.html

for interest....

We had an un-managed network that built up and built up over the years, with switches here there and everywhere.
When we had an issue with network dropping off, we did not know where to start.
With plenty of planning, we now have a brand new managed network, and we know where all the cables go.

But then, we have a number of VLANS due to the complexity of our system.

Back when, managed switches where helped a lot when most EthernetI/P traffic was all broadcast traffic instead of unicast. Now days it is not as big of an issue.



Managed switches are used when you need to do VLANs and Routing. They also give you some useful diagnostic tools. It really depends on what kind of managed switches you have and what you are trying to do.

I’m in the “when shouldn’t you use a managed switch” in an industrial automation application. First, a small clarification, there is a difference between an unmanaged switch and a hub. Unmanaged switches will still filter traffic to a basic level so that not every port see all traffic. Hubs are simple repeaters. Any traffic coming in on one port gets repeated on all the others. In today’s world you most certainly don’t want to use a hub unless you are simply connecting one device to another. Having said that, hubs are required if you are doing diagnostics with something like wireshark and you need to see exactly what is coming out of / going into a specific Ethernet port.
With the complexity of network traffic these days managed switches reduce the amount of traffic any one device must process. If an Ethernet packet is received by a device (say a PLC), even if that packet is not meant for that device, the only way that device can determine that is to process it. If it is for that device then it uses it, if not it dumps it, either way it has processed it and that takes time and resources. A managed switch will block the packet (in most cases) from ever reaching the device in the first place. There are a lot of other reason most of which are way over my head but probably the best way to look at it is, in the overall system the switch is one component in potentially hundreds when considering the processors, I/O cards, sensors, drives, etc… however, that one component can make the communications far more efficient (and I mean dramatically more efficient) if you spend a little bit more upfront buying managed switches rather than unmanaged ones.

Firejo said:

There are a lot of other reason most of which are way over my head but probably the best way to look at it is, in the overall system the switch is one component in potentially hundreds when considering the processors, I/O cards, sensors, drives, etc… however, that one component can make the communications far more efficient (and I mean dramatically more efficient) if you spend a little bit more upfront buying managed switches rather than unmanaged ones.

Click to expand...

That can be true, but only if the managed switches are setup correctly. If setup incorrectly, or not at all, the switches function exactly like a really expensive unmanaged switch and the only thing they have done is cost significantly more money. I'd prefer to have a good industrial grade unmanaged switch than a poorly configured office grade managed switch any day of the week.

So if an unmanaged switch can handle unicast and only direct traffic to the port it needs to go, and a managed switch still hits all ports when a device does broadcast, how is a managed switch any more efficient at managing traffic? I wouldn't think it would be for simple star networks.

It depends on the application and you should also consider the audience. If you have 20 controllogix PLC's with Flex IO, I would personally have some type of switch on there with some brains for the times when you have issues and can't figure out why. Earlier versions of RSLogix (version 17 and below I think) used multicast for stuff like Flex IO. This would cause issues with unmanaged switches. Later versions use unicast which is better.

Along with VLANs and IGMP, one of the biggest benefits is the event logs. I had a system that was losing communications and with the event log, I tracked it down to an automatic server backup that IT was doing.

Standard office networks can handle late or missing packets and generally nobody will notice that their print job took two seconds longer to reach the printer. IT only hears about it when their IP phones start dropping calls.

On the other hand, If the plant is maintained by people that are going to need to troubleshoot this, managed switches can be a pain for them if they're not trained well. I had a group of electricians that removed managed switches because they had network issue. They replaced them with unmanaged switches and the it took the network to it's knees because the root cause was broadcast storm due to a patch cord jumpered in the switch. The managed switch took care of the problem and was noted in the log, but the electricians didn't know how to use it.

Unmanaged versus Managed Switches
https://www.cisco.com/c/dam/en/us/p...s_products_genericcontent0900aecd806c7afe.pdf

As the doc says managed can prioritize traffic in a group of devices for example a PLC and its I/O modules .

Helliana said:

That can be true, but only if the managed switches are setup correctly. If setup incorrectly, or not at all, the switches function exactly like a really expensive unmanaged switch and the only thing they have done is cost significantly more money. I'd prefer to have a good industrial grade unmanaged switch than a poorly configured office grade managed switch any day of the week.

Click to expand...

I can't say I disagree with that but isn't that kinda like this?
https://www.youtube.com/watch?v=zCrn-VJmpgE
If you don't use the equipment correctly you have no one to blame but yourself

Firejo said:

I can't say I disagree with that but isn't that kinda like this?

Click to expand...

So that one was great... but this was the next one up https://www.youtube.com/watch?v=7KvxOuC7Bhc

I now have tears in my eyes

Personally, my answer is this: managed switches give you plenty of fancy capability, but a significant portion of the time you don't need that. What you DO need is a way to find out what is going wrong. Unmanaged switches just give you blinky lights; and that won't do much more than tell you you have a problem. You already KNOW you have a problem, which is why you have the cabinet open in the first place.

Managed switches will give you many different ways to help detect errors, speed up commissioning, and even do predictive maintenance. The ones I see typically have cable testers built in to see if a cable is good. They have event logs to track what is happening. They have loop detection, to help prevent broadcast storms from a loop. They have error counters, so you can see the error rate is increasing and dive in further. Fiber units often give signal quality on the optics.

Helliana said:

That can be true, but only if the managed switches are setup correctly. If setup incorrectly, or not at all, the switches function exactly like a really expensive unmanaged switch and the only thing they have done is cost significantly more money. I'd prefer to have a good industrial grade unmanaged switch than a poorly configured office grade managed switch any day of the week.

Click to expand...

I'd rather yet have a good industrial grade managed switch. The ones I use come with 2 versions you can order, with settings defaulted to good EIP defaults or good PN defaults. That means you can mostly treat it as an unmanaged switch until you actually need it to be managed.

Firejo said:

I can't say I disagree with that but isn't that kinda like this?
https://www.youtube.com/watch?v=zCrn-VJmpgE
If you don't use the equipment correctly you have no one to blame but yourself

Click to expand...

To be fair, I feel like that guy did a pretty good job for an hour's work. I think that's actually an amazing metaphor for a lot of networks I see, where everything is horribly misconfigured, but it happens to still be working anyway.

Small standalone equipment or skidded equipment I would use unmanaged.

When I start looking at integrating smaller standalone machines into complete coordinated lines, integrating SCADA/MES Systems/complex IO systems, components from a diverse range of manufacturers, or distributed systems then I immediately go managed. Auto-MDIX/Autonegotiate ports are amazing but don’t always work correctly for various reasons. Managed switches let you force port configs to 100mbps at full duplex to prevent errors. They also give you tons of troubleshooting tools. I just troubleshot a cable today on a machine half way across the country by telnetting into a managed switch. Without that feature I would have had to call a network contractor to come to the plant and assist or spend hours doing process of elimination. If your potential cost of downtime is greater than $50/min I would go managed all the way, but only if you intend on using the tools.