Network loop

[RajaHassamIrfan86583]

I am facing an issue. My network gets unstable for a minute and port of one switch goes to error disable and reason i get is loopback. I am not able to identify the issue. i have enabled err disable loopback but it makes network unstable for some time when there is issue if i disconnect that one switch from the network. the whole network works fine there is no time out then. The loop is detected on interface which is connected to root Switch. Conf of the switch having issue is attached. 

[MHM Cisco World]

There is l2 loop'

Can you share the topolgy 

MHM

[RajaHassamIrfan86583]

Switches are connected as figure and  RSTP is used on all switches

[MHM Cisco World]

Show spanning tree 

Share output 

MHM

[RajaHassamIrfan86583]

Spanning tree pix attached

[Ruben Cocheno]

@RajaHassamIrfan86583 

Make sure that you don't have STP disabled on any port of that switch that you disconnected. You can also disable all ports and leave only the uplinks up, and enable port by port if you are not sure what port is causing problems. Also check the logs

[RajaHassamIrfan86583]

@Ruben Cocheno I have done this but this didnt solved the issue. In logs it shows loopback detected on main cable connected the root switch

[RajaHassamIrfan86583]

I have enabled loopback recovery but it disrupts the whole network which is creating issues for all users

[Ruben Cocheno]

@RajaHassamIrfan86583 

if the root cause is the main cable, then remove it if you have redundancy for that. If not check STP on the switch after that main cable/

[RajaHassamIrfan86583]

when i remove the cable of that switch the network works smoothly but when plugged in it again start same issue and not able to odentify the problem 

[MHM Cisco World]

The topolgy you share is hub and spoke and you share multi show spanning tree 

Can yoh share only the show spanning tree (and summary) of hub and switch that have issue 

MHM

[RajaHassamIrfan86583]

VLAN0001
Spanning tree enabled protocol rstp
Root ID Priority 16385
Address 3c26.e43c.bf00
Cost 4
Port 1 (GigabitEthernet0/1)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 885a.9207.d100
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi0/1 Root FWD 4 128.1 P2p
Gi0/9 Desg FWD 19 128.9 P2p
Gi0/11 Desg FWD 19 128.11 P2p
Gi0/13 Desg FWD 19 128.13 P2p
Gi0/15 Desg FWD 19 128.15 P2p
Gi0/17 Desg FWD 19 128.17 P2p
Gi0/19 Desg FWD 4 128.19 P2p

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------

Gi0/23 Desg FWD 19 128.23 P2p

Summary

Root bridge for: none
EtherChannel misconfig guard is enabled
Extended system ID is enabled
Portfast Default is disabled
Portfast Edge BPDU Guard Default is disabled
Portfast Edge BPDU Filter Default is disabled
Loopguard Default is enabled
PVST Simulation Default is enabled but inactive in rapid-pvst mode
Bridge Assurance is enabled
UplinkFast is disabled
BackboneFast is disabled
Configured Pathcost method used is short

Name Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
VLAN0001 0 0 0 8 8
---------------------- -------- --------- -------- ---------- ----------
1 vlan 0 0 0 8 8