Problem Description

For OSN1500 NG-SDH equipment fan speed regulation scheme, R3 and previous versions and R6 and later versions are not the same, so the results returned by using cfg-get-fanspeed query are not the same, for example:

Host version: 5.21.12.42

:cfg-get-fanspeed

FAN-SPEED

FAN-SPEED XC-HIGHEST-TEMPERATURE

auto(mid) 38

Total records :1

Host version: 5.21.16.13

:cfg-get-fanspeed

FAN-SPEED

FAN-SPEED MINIMUM-DISPERSION

auto(high) 580

Total records :1

So what is the exact speed scheme and how do I interpret the returned results?

Warning message

None

Processing

Understand the return result of cfg-get-fanspeed according to the corresponding fan speed regulation scheme.

Root cause

For NGSDH equipment, versions before R6 performed fan speed regulation based on the temperature of the network element, so the cfg-get-fanspeed command returns the results of the fan speed and the temperature monitored by the cross-board.

R6 and later performs temperature adjustment based on the temperature difference, which is the difference between the maximum normal operating temperature allowed for the critical chips on the single board and the current temperature.

The automatic fan speed regulation scheme considers two change processes, speed regulation to high and speed regulation to low:

Speed up

The main control regularly reads the temperature values and tolerated temperature difference reported by all the single board sensors. As long as any single board detects the temperature and the calculated tolerated temperature difference is less than 40°C ( =40 degrees), the fan switches from low speed to medium speed.

The main control regularly reads the temperature values and tolerance temperature difference reported by all single board sensors. As long as any single board detects the temperature and the calculated tolerance temperature difference is less than 30℃ ( =30 degrees), the fan switches from medium speed to high speed.

Switching speed to low

In order to prevent repeated changes in fan speed at the point of speed change, set the temperature return difference, the main control reads the temperature value and tolerance temperature difference reported by all single board sensors at regular intervals, all single boards detect the temperature, and the calculated tolerance temperature difference is less than 38 ℃ (= 38 degrees), the fan is switched from high-speed to medium-speed, or else the status quo is maintained.

The main control regularly reads the temperature value and tolerance temperature difference reported by all single board sensors, all single boards detect the temperature, and the calculated tolerance temperature difference is less than 48℃ ( =48 degrees), the fan switches from medium speed to low speed, otherwise the status quo is maintained.

In addition, the fan will run at full speed in the following cases:

1. The fan will run at full speed for network elements using old cross boards:

3500: SSN1GXCSA, SSN1EXCSA, SSN1UXCSA, SSN1UXCSB

7500: sst1gxcsa, sst1gxcsb

2500: ssq1cxl, ssq2Cxl

2500REG: SSQ1CRG

2、Main control board power on initial, or the main control is not in position, the fan runs at full speed;

3、Auto-speed mode, as long as one of the fans is detected offline ( BD_STATUS ), the other fans run at full speed;

4、Auto-speed mode, as long as one of the fans is detected as fault FAN_FAIL alarm, the other fans run at full speed.

5、Using SSN1FAN and SSN1XDS board with the network element, the fan will run at full speed.

Recommendations and Summary

The fan speed regulation scheme of R6 is too complicated and not reasonable enough, R&D plans to optimize it in the subsequent versions.

The current R9C04 version still uses the same speed control scheme as the R6 version.