Network Loop Detection

jctech2025
Comes here often

Network Loop Detection

Hi All,

I recently Was working with Cisco Meraki support to troubleshoot a problem AP. We discovered it's gonna need to be replaced. However while looking into it, we ran a packet capture on the switch the ap is connected to and we noticed that there are thousands of frames being sent by netgear with RLDP loop detection packets. I had to install probably 150 netgear switches in the building because they went to VOIP for their phone system.

If I look at the capture in Wireshark I see, abbreviated:
Source - Netgear
Protocol - RLDP
Info - Network Loop Detection

Is this saying that a loop is being detected on the network, or that a loop is being looked for? I checked the manual for the switch and "Loop Detection" is from what I read disabled by default. There has been complains about latency in the building. I don't know that this would factor in, however I wanted to ask the community.

 

I'm also asking in the forum as the original capture was taken from the Meraki Dashboard.

Thoughts?

2 Replies 2
Brash
Kind of a big deal
Kind of a big deal

I don't have any Netgear switches but logically from what you're seeing, it sounds likely that the Netgear switches are sending broadcast frames for loop detection. The idea would be that if the same frame is then received on the port that originally sent it, there is a loop detected in the network. Similar to (or the same as) spanning-tree BPDU's.

 

Depending on how many broadcasts you have flying around, it's possible that could impact your network.

jctech2025
Comes here often

Yeah, this is the first I have heard about this type of broadcast.  I have tested from multiple devices and I am seeing the same traffic.  I'm trying to determine if it is a loop or if it is a check for a loop, either way it is the most traffic on the wire.  I have never had to log into one of these devices before either.

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