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Cisco switch not powering up a few phones

We are having a POE issue on some ports on a Cisco SG500-52MP.  About 5 users phones are not powering up.  We eliminated a cabling issue and a phone issue by plugging in the phones directly to the Cisco switch, however some ports are not powering up the phones.  For instance.

Joe's phone is not working and was plugged into port 25
Mary's phone is working and is plugged into port 41

If we swap phones, Mary's phone does not power up on port 25 and Joe's phone powers up on port 41.  This tells us something is going on with the switch.  We don't want to power cycle the switch just yet as other workstations are working.  The system has been up and running for about a year and no changes were made.

Is there something that we can look for on the switch itself to see why those 5 particular ports are not powering up the phones?
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ptsolutionsinc
Asked:
ptsolutionsinc
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1 Solution
 
atlas_shudderedSr. Network EngineerCommented:
Are you managing via gui or cli?

Are these new phones or existing that just stopped working?
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ptsolutionsincAuthor Commented:
managed via the gui.

existing phones that stopped working.
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atlas_shudderedSr. Network EngineerCommented:
okay.   Can you get into the cli?
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Andy BartkiewiczNetwork AnalystCommented:
What type of phones do you have?
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ptsolutionsincAuthor Commented:
i can get into cli if need be.  im not too familiar with cli but i know how to follow directions.  They are polycom VVX310
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atlas_shudderedSr. Network EngineerCommented:
okay, log into the switch and run the following command:

show power inline

Open in new window


and post the output to the question
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ptsolutionsincAuthor Commented:
port 25 which is one of the ports that is not powering up the phone shows Status off
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atlas_shudderedSr. Network EngineerCommented:
The out put should look something like this:

show power inline ?   
  GigabitEthernet  GigabitEthernet IEEE 802.3z
  module           Limit display to interfaces on module
  police           Show inline power police
  priority         Show inline power priority
  |                Output modifiers
  <cr>

LON-KY-SW205.24.20#show power inline 

Module   Available     Used     Remaining
          (Watts)     (Watts)    (Watts) 
------   ---------   --------   ---------
1          1440.0       44.1      1395.9
Interface Admin  Oper       Power   Device              Class Max
                            (Watts)                            
--------- ------ ---------- ------- ------------------- ----- ----
Gi1/0/1   auto   on         6.3     IP Phone 7942       2     30.0 
Gi1/0/2   auto   on         6.3     IP Phone 7912       n/a   30.0 
Gi1/0/3   auto   on         6.3     IP Phone 7940       n/a   30.0 
Gi1/0/4   auto   on         6.3     IP Phone 7912       n/a   30.0 
Gi1/0/5   auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/6   auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/7   auto   on         6.3     IP Phone 7940       n/a   30.0 
Gi1/0/8   auto   on         6.3     IP Phone 7940       n/a   30.0 
Gi1/0/9   auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/10  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/11  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/12  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/13  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/14  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/15  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/16  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/17  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/18  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/19  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/20  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/21  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/22  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/23  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/24  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/25  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/26  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/27  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/28  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/29  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/30  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/31  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/32  auto   faulty     0.0     n/a                 n/a   30.0 
Gi1/0/33  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/34  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/35  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/36  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/37  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/38  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/39  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/40  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/41  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/42  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/43  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/44  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/45  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/46  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/47  auto   off        0.0     n/a                 n/a   30.0 
Gi1/0/48  auto   on         6.3     IP Phone 7940       n/a   30.0 

Open in new window

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Andy BartkiewiczNetwork AnalystCommented:
Looks like the phones draw 15.4W. Depending on the switch type you have the maximum output on POE may be 375W. So that would mean that you can have a maximum of 24 phones on your switch.
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ptsolutionsincAuthor Commented:
here is the output

CiscoSG500-2#show power inline

Port based power-limit mode
Inrush Test: Enable
Legacy Mode: Enable

Unit  Power  Nominal Power   Consumed Power   Usage Threshold   Traps   Temp (C)                
---- ------- ------------- ------------------ --------------- --------- --------                
 1     On      740 Watts     30 Watts (4%)          95         Disable     48                    


  Port      Powered Device         State          Status    Priority   Class
-------- -------------------- ---------------- ------------ -------- ---------
gi1/1/1                             Auto           Off        low     class4
gi1/1/2                             Auto           Off        low     class4
gi1/1/3                             Auto           Off        low     class4
gi1/1/4                             Auto           Off        low     class4
gi1/1/5                             Auto           Off        low     class4
gi1/1/6                             Auto           Off        low     class4
gi1/1/7                             Auto        Searching     low     class4
gi1/1/8                             Auto            On        low     class2
gi1/1/9                             Auto            On        low     class2
gi1/1/10                            Auto            On        low     class2
gi1/1/11                            Auto            On        low     class2
gi1/1/12                            Auto            On        low     class2
gi1/1/13                            Auto        Searching     low     class4
gi1/1/14                            Auto        Searching     low     class4
gi1/1/15                            Auto            On        low     class2
gi1/1/16                            Auto            On        low     class2
gi1/1/17                            Auto            On        low     class2
gi1/1/18                            Auto        Searching     low     class4
gi1/1/19                            Auto        Searching     low     class4
gi1/1/20                            Auto        Searching     low     class4
gi1/1/21                            Auto        Searching     low     class4
gi1/1/22                            Auto        Searching     low     class4
gi1/1/23                            Auto        Searching     low     class4
gi1/1/24                            Auto        Searching     low     class4
gi1/1/25                            Auto           Off        low     class4
gi1/1/26                            Auto           Off        low     class4
gi1/1/27                            Auto           Off        low     class4
gi1/1/28                            Auto           Off        low     class4
gi1/1/29                            Auto           Off        low     class4
gi1/1/30                            Auto           Off        low     class4
gi1/1/31                            Auto        Searching     low     class4
gi1/1/32                            Auto        Searching     low     class4
gi1/1/33                            Auto        Searching     low     class4
gi1/1/34                            Auto        Searching     low     class4
gi1/1/35                            Auto        Searching     low     class4
gi1/1/36                            Auto            On        low     class2
gi1/1/37                            Auto            On        low     class2
gi1/1/38                            Auto        Searching     low     class4
gi1/1/39                            Auto        Searching     low     class4
gi1/1/40                            Auto        Searching     low     class4
gi1/1/41                            Auto        Searching     low     class4
gi1/1/42                            Auto        Searching     low     class4
gi1/1/43                            Auto        Searching     low     class4
gi1/1/44                            Auto        Searching     low     class4
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ptsolutionsincAuthor Commented:
here are the results of the other switch

 Port      Powered Device         State          Status    Priority   Class
-------- -------------------- ---------------- ------------ -------- ---------
gi1/1/1                             Auto        Searching     low     class4
gi1/1/2                             Auto        Searching     low     class4
gi1/1/3                             Auto        Searching     low     class4
gi1/1/4                             Auto            On        low     class2
gi1/1/5                             Auto          Fault       low     class4
gi1/1/6                             Auto            On        low     class2
gi1/1/7                             Auto        Searching     low     class4
gi1/1/8                             Auto        Searching     low     class4
gi1/1/9                             Auto            On        low     class2
gi1/1/10                            Auto          Fault       low     class4
gi1/1/11                            Auto          Fault       low     class4
gi1/1/12                            Auto            On        low     class2
gi1/1/13                            Auto            On        low     class2
gi1/1/14                            Auto          Fault       low     class4
gi1/1/15                            Auto            On        low     class2
gi1/1/16                            Auto            On        low     class2
gi1/1/17                            Auto        Searching     low     class4
gi1/1/18                            Auto        Searching     low     class4
gi1/1/19                            Auto            On        low     class2
gi1/1/20                            Auto        Searching     low     class4
gi1/1/21                            Auto        Searching     low     class4
gi1/1/22                            Auto            On        low     class2
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atlas_shudderedSr. Network EngineerCommented:
Okay, go into the webui and change the poe priorities for 25 and 17.  Change 25 to class 2 change 17 class 4.  Let your users know you are going to make this change because it may lead to the user on port 17 losing connectivity.  Once change is made, check phone connected to port 25 and let me know the results
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atlas_shudderedSr. Network EngineerCommented:
Okay, on the second switch run this command on the interfaces showing fault:

show pow inl gi1/1/5
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ptsolutionsincAuthor Commented:
why are we messing with port 17?
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ptsolutionsincAuthor Commented:
Also, port 41, the port that the phone works, is class 4 and port 25 is also class 4.  I don't see where to change classes in the gui.
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atlas_shudderedSr. Network EngineerCommented:
Port 17 is in a full on status with priority class 2.  What I am looking for is if the behaviour will follow on the transition.  If it does not, then we can isolate to a global power distribution issue.  If it does the port itself becomes more the suspect.
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atlas_shudderedSr. Network EngineerCommented:
sorry.  Change the priority level to high
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atlas_shudderedSr. Network EngineerCommented:
also please provide the output from:

show pow inl gi1/1/25
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atlas_shudderedSr. Network EngineerCommented:
No further input from asker
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