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SG300-28P: POE power drops every several minutes

richlafferty
Level 1
Level 1

Hi all,

We have an SG300-28P which, at intervals between 5 and 30 minutes or so, drops power to all of its POE-powered ports and then immediately restores power. The switch logs nothing when this happens other than recording that the ports went down and back up, even with debug logging enabled. Non-POE ports are not affected.

When the problem started there were only four POE-powered devices on the switch and we are far under our power budget. (While testing I added a fifth device, see below.)

Not all combinations of devices cause the drops to occur -- specifically, it looks like having devices on ports near each other causes the drops. When the drops occur, the absent counters of all of the POE devices increment. I noticed this earlier thread here seemed similar:

https://supportforums.cisco.com/thread/2165089

but in that case, he got no power at all in the adjacent configurations, instead of having it drop every several minutes.

I'm running

sw06#sh ver

SW version    1.1.2.0 ( date  12-Nov-2011 time  23:34:26 )

Boot version    1.1.0.6 ( date  11-May-2011 time  18:31:00 )

HW version    V02

I have the new 1.2.2.7.6 firmware ready to go, I'll update this when I have a chance to test it. Unfortunately it is a production switch, but it's one with relatively few devices on it so far. If need be, I've got an sf300-48p I can swap in to dedicate this sg300 to testing.

Thanks for anything you might suggest.

Here's the details:

-  "Phone" is an Avaya 4610SW or 5610SW IP phone (class 2)

- "Watchdog" is a IT Watchdogs Watchdog 100 environmental monitor (class 0)

- "WAP" is a Cisco WAP4410N (class 3)

First failing combination:

gi10 phone #1

gi22 phone #2

gi23 watchdog

gi24 wap

would cause POE power to drop on all those ports every 5-30 minutes.

I turned off Green Ethernet entirely -- no change.

Then did the following tests:

1. "power inline never" on gi23 and gi24: problem went away

2. "power inline auto" on gi23 and gi24:  problem came back

3. "power inline never" on gi23 only:     problem went away

4. "power inline auto" on gi23:           problem came back

5. "power inline never" on gi24 only:     problem went away

6. "power inline auto" on gi24:           problem came back.

I left gi23 powered down overnight and it was stable: made it ~10h without any issues.

This morning tried the following configs:


08:54 - worked fine

gi4 watchdog

gi10 phone #1

gi22 phone #2

gi24 wap


10:31 - added another phone, problem came back

gi4 watchdog

gi10 phone #1

gi22 phone #2

gi23 phone #3

gi24 wap


10:43 - moved phone #3 to gi11 (adjacent to gi12) -- problem continued

gi4 watchdog

gi10 phone #1

gi11 phone #3

gi22 phone #2

gi24 wap


11:00 - moved phone #3 to gi8 -- problem continued

gi4 watchdog

gi8 phone #3

gi10 phone #1

gi22 phone #2

gi24 wap


11:31 - moved phone #3 to gi14 -- problem went away

gi4 watchdog

gi10 phone #1

gi14 phone #3

gi22 phone #2

gi24 wap


and that's where we've left things right now, been stable for about four hours.

All of the following outputs are from the latest (11:31) config.

sw06#show power inline

Port based power-limit mode

Unit  Power  Nominal Power   Consumed Power   Usage Threshold   Traps  

---- ------- ------------- ------------------ --------------- ---------

1     On      180 Watts     18 Watts (10%)         95         Disable 

  Port      Powered Device         State          Status    Priority   Class  

-------- -------------------- ---------------- ------------ -------- ---------

  gi1                               Auto        Searching     low     class0  

  gi2                               Auto        Searching     low     class0  

  gi3                               Auto        Searching     low     class0  

  gi4                               Auto            On        low     class0  

  gi5                               Auto        Searching     low     class0  

  gi6                               Auto        Searching     low     class0  

  gi7                               Auto        Searching     low     class0  

  gi8                               Auto        Searching     low     class0  

  gi9                               Auto        Searching     low     class0  

  gi10                              Auto            On        low     class2  

  gi11                              Auto        Searching     low     class0  

  gi12                              Auto        Searching     low     class0  

  gi13                              Auto        Searching     low     class0  

  gi14                              Auto            On        low     class2  

  gi15                              Auto        Searching     low     class0  

  gi16                              Auto        Searching     low     class0  

  gi17                              Auto        Searching     low     class0  

  gi18                              Auto        Searching     low     class0  

  gi19                              Auto        Searching     low     class0  

  gi20                              Auto        Searching     low     class0  

  gi21                              Auto        Searching     low     class0  

  gi22                              Auto            On        low     class2  

  gi23                              Auto        Searching     low     class0  

  gi24            -                 Auto            On        low     class3  


-- watchdog:

sw06#show power inline gi4

  Port      Powered Device         State          Status    Priority   Class  

-------- -------------------- ---------------- ------------ -------- ---------

  gi4                               Auto            On        low     class0  

Power limit (for port power-limit mode): 15.400W

Port Status:               Port is on - valid resistor detected

Overload Counter:          0

Short Counter:             0

Denied Counter:            0

Absent Counter:            4

Invalid Signature Counter: 0

sw06#show interfaces advertise gi4               

Port: gi4      

Type: 1G-Copper

Link state: Up

Auto negotiation: Enabled

                                  1000f  1000h  100f  100h  10f  10h

                                  -----  -----  ----  ----  ---  ---

Admin Local link Advertisement    yes    no     yes   yes   yes  yes 

Oper Local link Advertisement     yes    no     yes   yes   yes  yes 

Oper Remote link Advertisement    no     no     yes   yes   yes  yes 

Priority Resolution               -      -      yes   -     -    - 


-- phone:

sw06#show power inline gi10

  Port      Powered Device         State          Status    Priority   Class  

-------- -------------------- ---------------- ------------ -------- ---------

  gi10                              Auto            On        low     class2  

Power limit (for port power-limit mode): 15.400W

Port Status:               Port is on - valid resistor detected

Overload Counter:          0

Short Counter:             0

Denied Counter:            0

Absent Counter:            465

Invalid Signature Counter: 0

sw06#show int adv gi10

Port: gi10     

Type: 1G-Copper

Link state: Up

Auto negotiation: Enabled

                                  1000f  1000h  100f  100h  10f  10h

                                  -----  -----  ----  ----  ---  ---

Admin Local link Advertisement    yes    no     yes   yes   yes  yes 

Oper Local link Advertisement     yes    no     yes   yes   yes  yes 

Oper Remote link Advertisement    no     no     yes   yes   yes  yes 

Priority Resolution               -      -      yes   -     -    - 


-- phone:

sw06#show power inline gi14

  Port      Powered Device         State          Status    Priority   Class  

-------- -------------------- ---------------- ------------ -------- ---------

  gi14                              Auto            On        low     class2  

Power limit (for port power-limit mode): 15.400W

Port Status:               Port is on - valid resistor detected

Overload Counter:          0

Short Counter:             0

Denied Counter:            0

Absent Counter:            0

Invalid Signature Counter: 0

sw06#show int adv gi14 

Port: gi14     

Type: 1G-Copper

Link state: Up

Auto negotiation: Enabled

                                  1000f  1000h  100f  100h  10f  10h

                                  -----  -----  ----  ----  ---  ---

Admin Local link Advertisement    yes    no     yes   yes   yes  yes 

Oper Local link Advertisement     yes    no     yes   yes   yes  yes 

Oper Remote link Advertisement    no     no     yes   yes   yes  yes 

Priority Resolution               -      -      yes   -     -    - 

sw06#


-- phone:

sw06#show power inline gi22

  Port      Powered Device         State          Status    Priority   Class  

-------- -------------------- ---------------- ------------ -------- ---------

  gi22                              Auto            On        low     class2  

Power limit (for port power-limit mode): 15.400W

Port Status:               Port is on - valid resistor detected

Overload Counter:          0

Short Counter:             0

Denied Counter:            0

Absent Counter:            591

Invalid Signature Counter: 166

sw06#show int adv gi22

Port: gi22     

Type: 1G-Copper

Link state: Up

Auto negotiation: Enabled

                                  1000f  1000h  100f  100h  10f  10h

                                  -----  -----  ----  ----  ---  ---

Admin Local link Advertisement    yes    no     yes   yes   yes  yes 

Oper Local link Advertisement     yes    no     yes   yes   yes  yes 

Oper Remote link Advertisement    no     no     yes   yes   yes  yes 

Priority Resolution               -      -      yes   -     -    - 


-- was watchdog, now empty:

sw06#show power inline gi23

  Port      Powered Device         State          Status    Priority   Class  

-------- -------------------- ---------------- ------------ -------- ---------

  gi23                              Auto        Searching     low     class0  

Power limit (for port power-limit mode): 15.400W

Port Status:               Port is off - detection is in process

Overload Counter:          0

Short Counter:             0

Denied Counter:            0

Absent Counter:            587

Invalid Signature Counter: 0


-- wap:

sw06#show power inline gi24

  Port      Powered Device         State          Status    Priority   Class  

-------- -------------------- ---------------- ------------ -------- ---------

  gi24            -                 Auto            On        low     class3  

Power limit (for port power-limit mode): 15.400W

Port Status:               Port is on - valid resistor detected

Overload Counter:          0

Short Counter:             0

Denied Counter:            0

Absent Counter:            607

Invalid Signature Counter: 3

sw06#show int adv gi24

Port: gi24     

Type: 1G-Copper

Link state: Up

Auto negotiation: Enabled

                                  1000f  1000h  100f  100h  10f  10h

                                  -----  -----  ----  ----  ---  ---

Admin Local link Advertisement    yes    no     yes   yes   yes  yes 

Oper Local link Advertisement     yes    no     yes   yes   yes  yes 

Oper Remote link Advertisement    no     no     yes   no    no   no  

Priority Resolution               -      -      yes   -     -    - 


Other useful bits:

sw06#show spanning-tree active

Spanning tree disabled (BPDU flooding) mode RSTP

Default port cost method:  long

sw06#sh ver

SW version    1.1.2.0 ( date  12-Nov-2011 time  23:34:26 )

Boot version    1.1.0.6 ( date  11-May-2011 time  18:31:00 )

HW version    V02

1 Accepted Solution

Accepted Solutions

Hi Rich, reference this picture I just drew- This is a rough interpretation of how a 24 port switch has for guts. Each + block represents a transformer. The corresponding numbers below represent the port bank which corresponds to the transformer. Of course POE MODULE is clearly identified. Each POE module services 12 ports.

I think you have a completely different issue. If the POE is working for 5-30 minutes, it may be a layer 1 issue (bad wires) or a different condition, perhaps equipment being disturbed. If the switch is at fault, it would seem more likely to be a defective than a buggy unit.  I have done a lot of extensive research on how the switch ASIC, transformer and POE modules work in cohesion.

Quite frankly, I think you should upgrade to the 1.2.7.76 firmware, factory reset the unit and test any ports you'd like using the same equipment. If the POE keeps dropping off every 5-30 minutes and you are absolutely positive it is not a layer 1 issue or a configuration issue on your products, I'd just replace the switch.

-Tom
Please rate helpful posts

-Tom Please mark answered for helpful posts http://blogs.cisco.com/smallbusiness/

View solution in original post

6 Replies 6

Tom Watts
VIP Alumni
VIP Alumni

Hello Rich, the case I created for the other gentlemen, John White is 622799757. Currently, this case status is pending more testing from the development team. However, his scenario is using Ruckus 7982 AP.

The important thing to note I think is how the port transform and poe modules interact. The port transformer services 4 ports

1,2,13,14

3,4,15,16

etc

In theory you should be able to connect every other port without issues such as;

1, 3, 5, 7

13, 15, 17, 19

etc

To keep this very simple;

Connect phone #1 to port 1

Connect phone #2 to port 2

Connect phone #3 to port 13

Connect ap #1 to port 14

Do these devices 1 at a time until they are fully powered. Do not connect them all at the same time.

What is the result?

-Tom
Please rate helpful posts

-Tom Please mark answered for helpful posts http://blogs.cisco.com/smallbusiness/

Did so (with ports 3, 4, 15, 16 -- port 1 is a trunk to another switch so I didn't want to repatch it.)

I haven't seen POE power bounce in the last ten minutes or so. I did notice one slight anomaly when the AP was coming up:

11-Sep-2012 17:05:41 %LINK-I-Up:  gi16

11-Sep-2012 17:05:46 %LINK-W-Down:  gi16

11-Sep-2012 17:05:48 %LINK-I-Up:  gi16

11-Sep-2012 17:05:50 %LINK-W-Down:  gi16

11-Sep-2012 17:05:51 %LINK-I-Up:  gi16

but I suspect that might just be a weirdness of the AP. I'll let this soak overnight -- I'm about to head out for the day, and sometimes the cycle is as long as a half hour when it does happen. If there's something else you'd like me to test following this test, let me know, and I'll provide that tomorrow morning along with whether or not this was stable overnight.

The watchdog is currently disconnected, so these four are the only POE devices on the switch.

I'm out of the office for most of tomorrow.

Hey Tom,

The switch was stable overnight with three phones and the WAP in 3, 4, 15, 16.  The Watchdog is still disconnected. What's the next step?

Hi Rich, reference this picture I just drew- This is a rough interpretation of how a 24 port switch has for guts. Each + block represents a transformer. The corresponding numbers below represent the port bank which corresponds to the transformer. Of course POE MODULE is clearly identified. Each POE module services 12 ports.

I think you have a completely different issue. If the POE is working for 5-30 minutes, it may be a layer 1 issue (bad wires) or a different condition, perhaps equipment being disturbed. If the switch is at fault, it would seem more likely to be a defective than a buggy unit.  I have done a lot of extensive research on how the switch ASIC, transformer and POE modules work in cohesion.

Quite frankly, I think you should upgrade to the 1.2.7.76 firmware, factory reset the unit and test any ports you'd like using the same equipment. If the POE keeps dropping off every 5-30 minutes and you are absolutely positive it is not a layer 1 issue or a configuration issue on your products, I'd just replace the switch.

-Tom
Please rate helpful posts

-Tom Please mark answered for helpful posts http://blogs.cisco.com/smallbusiness/

Hi Thomas,

Upgrading the firmware seems to have done it. We've been stable (knock on wood!) for about a month now. Thanks for your help!

myanuary
Level 1
Level 1

yesterday, i've an issue like that on catalyst 4507...

two ip phone suddenly "off", and when i try to connect it on another port, it's "on" again..

the poe status is auto...

so i try to connect it to my pc, and the link is up, then i connect it again to ip phone again and magically it's "on" again...

i don't know why suddenly the poe "die" and "live" again, i am still curious if this happen again..

what a strange problem...