topic Re: Loop-detection with Delta equipement (furnace) shutdown port when power outage. in ICX Switches

Loop-detection with Delta equipement (furnace) shutdown port when power outage.

ala_ma — Thu, 27 Feb 2020 16:28:30 GMT

We have a network with ICX7250 switches and loop-detection activated on ports. On some Delta equipments (for furnace control), when it have a power outage, the switch detect a loop and shutdown the port. The port come down when the power is lost, not when it come back. If we make a debug, we can see the loop detection packet come back on the switch. The equipment continu to make some packet transfert before shuthing down. If we remove the loop detection protection, the loop goes on the router and make many next hop router errors. Even if we change that equipement it's the same problem. For us, it's clear that the problem come from the design of this equipment. Is there any way to disable loop detection and configure the router to prevent problem coming from that equipment?
Thank you

Re: Loop-detection with Delta equipement (furnace) shutdown port when power outage.

netwizz — Fri, 28 Feb 2020 14:14:38 GMT

Good Morning:

If the connected interface is going into an error-disabled state due to loop-detection during a power-outage, most likely some other piece of equipment is behaving strangely reflecting the loop-detection frames (PDU for Layer-2 where "Packet" is the PDU for Layer-3) are being reflected back at the ICX unit.

Specifically, the way loop-detection works is that the same switch that generates the loop-detection will recognize it should it come back into another Interface. This normally happens when there is a loop in the network topology.

Usually when you see a route change notification in the logging, it is because the ARP table reflects the next-hop IP available via a MAC address that is reachable via a different interface.

Does the device you are reaching go through something else and have two (2) connections to your Rucks ICX devie?

You will need to explain more about your network topology to get better support.

I can assure you the loop-detection works extremely well in every implementation we have tried. Its only downside we have found is if you have multiple units they pass it through transparently... i.e. you run loop-detection on a VLAN, if that VLAN crosses a trunk (i.e. a link between switches carrying multiple VLANs) that if someone loops something (i.e. connecting an Avaya VoIP phone on two interfaces that go to different closets or switches), the loop-detection frame will get picked up and passed through the other devices which do not recognize it as theirs, and it gets back to the switch that made the loop-detection frame only on a trunk or fiber link.

All that said, what about just not making loops? or using spanning-tree, which is excellent at mitigating loops?

Re: Loop-detection with Delta equipement (furnace) shutdown port when power outage.

ala_ma — Tue, 03 Mar 2020 19:15:27 GMT

Hello,
the equipment have only one network connector plug and he's plugged directly in a ICX7250. The ICX7250 is plug in a router ICX6610.

We made many others tests. On a ICX6450, the loop-detection dont shutdown the port with the same equipment. It seem to happends only with ICX7250. I tried many software version 08030, 08070 and 08090. No difference.
Finaly I think I will put a shutdown disable for that device.
bye