How to fix STP loop error on HP A5500 and HP V1810 switches?

**Gowravaram** · 14-02-2012

Currently I am having 2 x A5500 switches and 1 x V1810 switch. I tried to create a extra links to either of A5500 switches. But it result into looping error.
Core 1 and 2 and port 32 are connected together and set them to the hybrid ports. RSTP was enabled on the both the switched. Core 1 was primary root where as Core 2 was primary root. Rest of all the STP values are supposed to be default.
On the Core 1, Gi1/0/1 is supposed to be fiber uplink to the V1810 port 52. And on the Core 2 the Gi1/0/28 was RJ45 uplink to V1810 to the port 48.
When I am typing dis stp bri on the both the switches it is giving below mentioned output.

[Core 1]dis stp bri
MSTID Port Role STP State Protection
0 GigabitEthernet1/0/1 DESI FORWARDING NONE
0 GigabitEthernet1/0/32 DESI FORWARDING NONE

[Core 2]dis stp bri
MSTID Port Role STP State Protection
0 GigabitEthernet1/0/28 DESI FORWARDING NONE
0 GigabitEthernet1/0/32 DESI FORWARDING NONE

[Core 1]dis stp
-------[CIST Global Info][Mode RSTP]-------
CIST Bridge :0.3ce5-a667-d4a6
Bridge Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20
CIST Root/ERPC :0.3ce5-a667-d4a6 / 0
CIST RegRoot/IRPC :0.3ce5-a667-d4a6 / 0
CIST RootPortId :0.0
BPDU-Protection :disabled
Bridge Config-
Digest-Snooping :disabled
CIST Root Type

RIMARY root
TC or TCN received :74
Time since last TC :0 days 0h:10m:1s

----[Port1(GigabitEthernet1/0/1)][FORWARDING]----
Port Protocol :enabled
Port Role :CIST Designated Port
Port Priority :128
Port Cost(Dot1T) :Config=auto / Active=20000
Desg. Bridge/Port :0.3ce5-a667-d4a6 / 128.1
Port Edged :Config=disabled / Active=disabled
Point-to-point :Config=auto / Active=true
Transmit Limit :10 packets/hello-time
Protection Type :None
---- More ---- [16D [16D MST BPDU Format :Config=auto / Active=legacy
Port Config-
Digest-Snooping :disabled
Rapid transition :false
Num of Vlans Mapped :4
PortTimes :Hello 2s MaxAge 20s FwDly 15s MsgAge 0s RemHop 20
BPDU Sent :313
TCN: 0, Config: 0, RST: 313, MST: 0
BPDU Received :0
TCN: 0, Config: 0, RST: 0, MST: 0

[Core 2]dis stp
-------[CIST Global Info][Mode RSTP]-------
CIST Bridge :4096.b8af-670a-ca80
Bridge Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20
CIST Root/ERPC :0.3ce5-a667-d4a6 / 20
CIST RegRoot/IRPC :4096.b8af-670a-ca80 / 0
CIST RootPortId :128.26
BPDU-Protection :disabled
Bridge Config-
Digest-Snooping :disabled
CIST Root Type

ECONDARY root
TC or TCN received :38
Time since last TC :0 days 0h:12m:6s

----[Port28(GigabitEthernet1/0/28)][FORWARDING]----
Port Protocol :enabled
Port Role :CIST Designated Port
Port Priority :128
Port Cost(Legacy) :Config=auto / Active=20
Desg. Bridge/Port :4096.b8af-670a-ca80 / 128.28
Port Edged :Config=disabled / Active=disabled
Point-to-point :Config=auto / Active=true
Transmit Limit :10 packets/hello-time
Protection Type :Loop
MST BPDU Format :Config=auto / Active=legacy
Port Config-
Digest-Snooping :disabled
Num of Vlans Mapped :4
PortTimes :Hello 2s MaxAge 20s FwDly 15s MsgAge 1s RemHop 20
BPDU Sent :853
TCN: 0, Config: 0, RST: 853, MST: 0
BPDU Received :0
TCN: 0, Config: 0, RST: 0, MST: 0

Is there any solution to overcome from the above mentioned problem?

**Bahumathi** · 14-02-2012

Tell me whether STP is configure on V1810. If you have not done the same then I am suggesting that you should drop bpdus and it will simply remove the loop error from your situation.

**Gowravaram** · 14-02-2012

I wanted to appreciate you for posting your quick response. I came across V1810 does not support for STP. So after going through the response of yours I would not be able to get redundant uplinks on V1810 switch of mine. Give me brief idea on the above mentioned matter. Thanks a lot in advance.

**TABLITA** · 14-02-2012

It won’t be the case if v1810 is going to discard STP BPDUs. That would be the case if you are able to loop it. another thing which you can try over here is to connect both the switches to in ARF and after that make use of distributed portchannel in order to dual connect with v1810. However the thing is that if there are no support for STP then I don’t think so there would be support for the portchannel.

**Caelyn** · 14-02-2012

To fix the issue you can give a try to loop prevention mechanism on 1810 switch. Also you can give a try to loop-detection action command on Trunk port of the A5500.