Stratix 5700 comm loss when connecting downstream Stratix switches

radfahrer

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Nov 2006
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Just polling here to see if anyone else has observed an issue with Stratix 5700 switches similar to what I've been seeing. At our site we have a 5700 as the main switch in our PLC panel, then we have another one in an MCC. When we connect the MCC switch to the main switch, we notice several (don't remember if it's all of them or not) of the LED port status indicators change from green to yellow for about a minute and then they go back to green. If I'm connected to a PLC with Logix5000 through the main switch, then I get disconnected when this happens. After the lights go back to green, everything is back to normal.

There is another integrator on this project and he's said he's seen this behavior before at other sites and they kind of just live with it. I'm planning to contact Rockwell at some point to see if they know what is going on here, but figured I'd check here to see if I'm the only one seeing this type of issue or if this is a more common phenomenon. The switches are pretty much in their default config, the only thing we've done is set them up with IP addresses.

Any feedback is appreciated...

-G
 
I believe the yellow is the switch "probing" the connected devices to see what sort they are, to workout how to best handle the traffic and whether or not to allow it in at all. Once they go green, you're connected and talking.

I think that if you set up smartports and tell each port what it's got, then it doesn't have to work it out by itself, and so you'll skip the yellow and go straight to green.
 
Is it typical for comms. to be lost during probing?

ASF,

Do you know if it's typical for comms. to be interrupted on already connected ports when this "probing" process is going on?

-G
 
During a last project we had multiple (Armor)Stratix 5700 switches and we had the exact same behavior. When we connected the switches together, the network (PLC,Studio5000) would completely drop for some time and then recover again. It was totally reproducible time after time.

I know we solved it, it had to do with the Spanning Tree Mode configured in the Stratix. Once we changed that on all switches, the problem was gone. But I am not sure anymore what exactly we had to change in the stratix configuration.

See following technotes, it has enough leads to solve it I think. :geek:

Ports Lose Connection when Connecting or Disconnecting Device on Stratix Switch
https://rockwellautomation.custhelp.com/app/answers/detail/a_id/65469/related/1

Stratix 5400/5700/8000/8300: Changing Spanning-Tree Mode
https://rockwellautomation.custhelp.com/app/answers/detail/a_id/62769/related/1
 
Spanning Tree definitely seems to be the issue

Basti504,

Thanks for the links. I had found the first one about the disconnect behavior and that had pointed me to the details on spanning tree and port mode. But I hadn't found the second one on the website and that has good info. Now I just need to figure out what to do! These switches have so many options, it's crazy...

My main lesson learned is "Don't use a managed switch unless you absolutely need it"...We've got a pretty simple network, and aren't really planning to use any of the advanced features of the switch...should have used a Stratix 2000 instead!

-G
 
Basti504,My main lesson learned is "Don't use a managed switch unless you absolutely need it"...
I gotta say I really disagree with this statement. You really need to learn more about your managed switches rather than opting for unmanaged as a default. All it takes is one data-hog device to bog down an unmanaged network and then your left scrambling, trying to find the culprit, with not much of a way to fix it. True, there are many features you may not need, but the ones you do are well worth it.

Just MHO.
 
Point well taken...

Steve,

Point well taken...I guess I just haven't had enough experience with using the switches to do troubleshooting to have seen that side of the equation, in general systems I've worked on are small enough that network bandwidth issues haven't come up. Will be interesting to see if we end up needing those features at this site since we've got the managed switches in there.

Just curious, are you using Stratix switches for your managed switches? And if so, how did you end up working around the issue I started this post with regards to. Did you end up using the smart port feature as Rockwell recommends, or did you follow the recommendations in the KB which required the Cisco commands to tailor the STP settings, or did you have some other solution?

-G
 
What I personally find of the managed switch thing is that when you unbox the switch, a lot of the fancy features are turned on by default instead of being enabled by the programmed who configured it because a) he needs the feature and b) knows what he is doing.

Often I see the managed switch being enabled with lots of features you don't need in that specific system or don't understand what it is doing. I fully love the integration with Studio5000 for diagnostics and such, but I'm sure not everybody needs or wants rapid spanning tree enabled by default, same with DHCP using express setup.
 
ASF,

Do you know if it's typical for comms. to be interrupted on already connected ports when this "probing" process is going on?

-G

I don't recall seeing this happen on already connected and talking ports - generally only when you first connect it, or if you change a setting in the connected device which forces it to drop off and reconnect to the network, or something. But in those cases, yes - it will not communicate with anything else until your light goes back to green.

Looks like you've got plenty of other information to keep you out of trouble for now, and we're already pushing the limits of my knowledge on the subject, so I'll go back to my corner now ;)
 
Be sure to make sure the Stratix has the latest firmware. We had all sorts of issues with these switches when they came with one of Rockwell's intellicenter MCCs. The firmware was full of bugs, which Rockwell did finally recognize as the root of our problems.

Enough time has passed that one would assume the firmware is stable, but doesn't hurt to check.
 
Without going into a lengthy post STP is very involved to setup correctly. It's a very useful feature but for the vast majority of installs the feature is not needed and can cause lots of problems if not setup correctly so it's best to disable it.

It comes enabled out of the box because that's how it's done on most enterprise grade equipment and the idea out of the box is to handle switch loops and avoid packet storms as many people pull these out of the box and connect equipment to the corporate network.

I will do a detailed post on STP for these switches later if people are interested.
 

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