Good afternoon all,
We have been experiencing a very interesting issue lately, and I figured I'd share in case any of you ran into the same issue.
A single modem causes ‘Full Carrier Utilization Signature’ (Standing Wave, Full Hay Stack) on 1,2,or in rare cases 3 upstream carriers.
We have multiple examples of the issue causing OV QOS call volume on the node. We see calls prior to the issue and during the issue, but once resolved the call volume stops.
Issue appears to happen mostly when either a single device or multiple devices go offline on a node, and goes back through the registration process.
Full Bandwidth utilization (Standing Wave).
ServAssure shows 100% CER and < 10dBmV US SNR
Causes excessive saturation on the remaining available channels.
Dynamic Modulation happens on the impaired frequency, down to QPSK.
All devices on the node go into partial service 8x3 or 16x3, due to the impairment.
It appears that a single Cisco device is causing the issue.
We identify the offending device by T4 Timeouts (DOCS-IF-MIB::docsIfCmStatusT4Timeouts.2)
The offending device has T4's in the 5-7000 range over a 2-3 hour period.
A reset of the device immediately clears the issue on the node.
Still investigating. Possible Cisco Software/Hardware issue.