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Port Flapping Switch

 
n811
Occasional Visitor

Port Flapping Switch

Greathings,

 

I got several Problems with my Network.
Some VoIP Phones will crash, Windows Applications will end up with "Not Responding".

I recognizied that i sometimes lose pings. In my humble oppinion the reason for this would be port flapping, but i can't find the reason for the port flapping. I've changed several cables.

 

 

My Infrastructure:

 

  • Two Locations conected via VPN
  • Problems just in smaler Location
  • 2 x HP J9727A 2920-24G-PoE+ Switch
  • 2 x HPE 5130 48G PoE+
  • ~50 PCs
  • 15 VoIP Phones
  • 5 VLAN

 

 

The portflapping looks like this:

 

%Jul  4 17:03:54:862 2019 Switch1 IFNET/3/PHY_UPDOWN: Physical state on the interface GigabitEthernet2/0/3 changed to down.
%Jul  4 17:03:54:892 2019 Switch1 IFNET/5/LINK_UPDOWN: Line protocol state on the interface GigabitEthernet2/0/3 changed to down.
%Jul  4 17:03:57:099 2019 Switch1 IFNET/3/PHY_UPDOWN: Physical state on the interface GigabitEthernet2/0/3 changed to up.
%Jul  4 17:03:57:102 2019 Switch1 IFNET/5/LINK_UPDOWN: Line protocol state on the interface GigabitEthernet2/0/3 changed to up.
%Jul  4 17:04:00:487 2019 Switch1 IFNET/3/PHY_UPDOWN: Physical state on the interface GigabitEthernet2/0/3 changed to down.
%Jul  4 17:04:00:513 2019 Switch1 IFNET/5/LINK_UPDOWN: Line protocol state on the interface GigabitEthernet2/0/3 changed to down.
%Jul  4 17:04:02:464 2019 Switch1 IFNET/3/PHY_UPDOWN: Physical state on the interface GigabitEthernet2/0/3 changed to up.
%Jul  4 17:04:02:475 2019 Switch1 IFNET/5/LINK_UPDOWN: Line protocol state on the interface GigabitEthernet2/0/3 changed to up.

 

 

What exactly does this mean?

Have these three devices triggered arround 54 disconects which results in rebuilding the spanning tree? Could my error be here?

 

 -------------- STP slot 1 TC or TCN count -------------
 MST ID   Port                                Receive  Send
 0        GigabitEthernet1/0/29               0        54   
 0        GigabitEthernet1/0/30               0        56   
 0        GigabitEthernet2/0/33               9        17

 

 

 

Both got 370W. Why is port 1/0/24 on Priority High with 10 W consumption while port 1/0/31 is on Critical with 3 W?

 

=========================================================
  ===============display poe device===============  
Slot  1: 
 PSE ID    Slot No.  SSlot No. PortNum   MaxPower(W)    State   Model           
 4         1         0         48        370.0          On      LSP7POEB        
Slot  2: 
 PSE ID    Slot No.  SSlot No. PortNum   MaxPower(W)    State   Model           
 7         2         0         48        370.0          On      LSP7POEB        
=========================================================
  ===============display poe interface===============  
 Interface    PoE       Priority  CurPower  Oper      IEEE  Detection           
                                  (W)                 Class Status              
 GE1/0/23     Disabled  Low       0.0       Off       0     Disabled            
 GE1/0/24     Enabled   High      10.4      On        0     Delivering Power    
 GE1/0/30     Disabled  Low       0.0       Off       0     Disabled            
 GE1/0/31     Enabled   Critical  3.0       On        2     Delivering Power    
 GE1/0/32     Enabled   Critical  2.5       On        2     Delivering Power    
 GE1/0/33     Enabled   High      3.1       On        2     Delivering Power    
 GE1/0/34     Enabled   High      3.2       On        2     Delivering Power    
 GE1/0/35     Enabled   High      3.1       On        2     Delivering Power    
 GE1/0/36     Enabled   High      3.1       On        2     Delivering Power    
 GE1/0/37     Enabled   High      3.1       On        2     Delivering Power    
 GE1/0/38     Enabled   High      0.0       Off       0     Searching           
 GE1/0/40     Enabled   High      3.0       On        2     Delivering Power    
 GE1/0/41     Enabled   High      3.0       On        2     Delivering Power    
 GE1/0/42     Enabled   High      3.2       On        2     Delivering Power    
 GE1/0/43     Enabled   High      3.3       On        2     Delivering Power    
 GE1/0/44     Enabled   High      0.0       Off       0     Searching           
 GE2/0/27     Disabled  Low       0.0       Off       0     Disabled            
 GE2/0/29     Enabled   High      3.0       On        2     Delivering Power    
 GE2/0/30     Enabled   High      0.0       Off       0     Searching           
 GE2/0/31     Disabled  Low       0.0       Off       0     Disabled            
 GE2/0/32     Enabled   Critical  0.0       Off       0     Searching           
 GE2/0/33     Enabled   High      5.5       On        3     Delivering Power    
 GE2/0/34     Disabled  Low       0.0       Off       0     Disabled            
 GE2/0/35     Enabled   High      3.3       On        2     Delivering Power    
 GE2/0/36     Enabled   High      3.1       On        2     Delivering Power    
 GE2/0/37     Enabled   High      3.0       On        2     Delivering Power    
 GE2/0/38     Enabled   High      2.5       On        2     Delivering Power    
 GE2/0/39     Enabled   High      3.1       On        2     Delivering Power    
 GE2/0/40     Enabled   High      0.0       Off       0     Searching           
 GE2/0/41     Enabled   Critical  2.5       On        2     Delivering Power    
 GE2/0/42     Enabled   High      0.0       Off       0     Searching           
 GE2/0/43     Enabled   High      0.0       Off       0     Searching           
 GE2/0/44     Enabled   High      3.0       On        2     Delivering Power    
 GE2/0/45     Enabled   High      3.1       On        2     Delivering Power    
 GE2/0/46     Enabled   High      2.7       On        2     Delivering Power    
 GE2/0/47     Enabled   High      2.6       On        2     Delivering Power    
 GE2/0/48     Enabled   Critical  2.8       On        2     Delivering Power    
   ---  On State Ports: 25; Used: 84.2(W); Remaining: 655.8(W)  ---

 

 

Any idea how i can find the reason for this annoying flaping?

 

 

---

n811

2 REPLIES 2
parnassus
Honored Contributor

Re: Port Flapping Switch

Port Flapping is just a symptom. The reason (or reasons) behind a Port Flapping can be tricky to diagnose.

First: triple check physical cabling...it should be certified end-to-end (from PC/VoIP Phone port to Switch port), after that check for looping...especially in involved VoIP Phones (I've seen idiots doing silly things on Ethernet Ports of VoIP Phones)...then you should check your VLANs (tagging for Voice) and Spanning Tree...and setup few Comware based (or ArubaOS-Switch based) commands to protect your network from loops and other nasty things that can happen on the edge side.

n811
Occasional Visitor

Re: Port Flapping Switch

Hi parnassus, 

 

thanks for your Reply.

 

Cable Check:

I dont think my issue is a result of bad cables because i had a VoIP Phone which wasn't working so i changed all cables.

The one from Phone to RJ45 port on the wall.
The port on the wall which will result in a new cable to my Patchpanel.
The cable from Patchpanel to Switch.
After i was finished the Phone still havent worked. So i unplugged the cable from the switch wich results in a shutdown of the phone cuz of removal poe. After i plugged it in again it worked.

 

Well i could had bad luck, but i don't think i got two brocken cables out of six. (different manufacturer)

 

Spanning tree:
STP isn't enabled on all switches. I guess here could be something. Correct me if i'm wrong. I never created a loop on a rackmounted switch on Purpose, but i did so on a small Desktop one. I thought a loop will permanent block my whole Network after one single broadcast have been send.

Could it be a loop?
Enable STP on all Switches and modify its priority should resolve it even if i got a loop somewhere, am i right?

 

---

n811