2960S Switch is disconnecting intermittently from the other 2960S Switch

[NELSON]

I need help.

I have a 2960S Switch (Sw-2) connected to 1 port of another 2960S Switch (Sw-1).  Both ports are configured as trunk with 3 allowed VLANs (1, 3 & 18).  If all ports of the Sw-2 are DISABLED, the ping to this Switch is continuous & no interruption.  But if all 9 ports (of this Sw-2 are ENABLED, the ping to Sw-2 is OK but after 15-25 minutes, there will be around 30-40 seconds disconnection (Request Time Out). This is the same situation during the whole day.

I have checked all LAN cables & I tried to isolate every switch port, but there is no problem with all ports & cables.

Below is the configuration of both interface.

SW-1

interface GigabitEthernet1/0/4
switchport trunk allowed vlan 1,3,18
switchport mode trunk
spanning-tree portfast

SW-2

interface GigabitEthernet1/0/23
switchport trunk allowed vlan 1,3,18
switchport mode trunk
spanning-tree portfast

Is there any additional configuration that I need to do to stabilized the connection?

Your support in solving this issue will be appreciated.

Many thanks!

[Mark Malone]

Hi

take this off should not be on trunk at all its specifically for access ports ,pc phones never use it between trunks it will cause issues

spanning-tree portfast

[Paul]

Second what Mark Malone said.

Read on BPDU guard and related packets.

[Leo Laohoo]

If all ports of the Sw-2 are DISABLED, the ping to this Switch is continuous & no interruption.  But if all 9 ports (of this Sw-2 are ENABLED, the ping to Sw-2 is OK but after 15-25 minutes, there will be around 30-40 seconds disconnection (Request Time Out).

Duhhhh ... WHAT???  "all 9 ports" are what?  Connected to each other in a non-Etherchannel?

WTF!  Someone wants to lose their job?

[nitesh.tomar1 · Accepted solution]

Hi Nelson,

Remove "spanning-tree portfast" from the config and then check

We use "spanning-tree portfast" on access ports and not on trunks

[NELSON]

Hi Nitesh,

I have removed the spanning-tree portfast in all trunk ports but the problem persists.  

[Mark Malone]

Hi Nelson as per Leos statement are these individual trunks all linked to the same switch , put them into an etherchannel , bundle all the trunks together to avoid STP issues happening , use LACP/PAGAP or just hardcode it on , quick guide below , do you have any topology of the setup you can provide so we can see what way its linked up?

http://www.dummies.com/programming/networking/cisco/etherchannel-configuration/