Integration of Cisco Core Switch 3850X and Cisco Access Switch C1000

[Herald Sison]

Hi Everyone,

i tried integrating 2 switches for office use Cisco Core Switch 3850X and Cisco Access Switch C1000 via copper uplink ports, when i tried to connect the two switches the whole network experienced some weird lag and slowness in the network performance.

is there something wrong with my configuration, 

core side port config:

interface GigabitEthernet1/0/44
description UPLINK to ACC-SW01
switchport mode trunk

i already have a static route from my core switch to my firewall and it is working fine,

ip route 0.0.0.0 0.0.0.0 172.21.1.1

access side port config:

interface GigabitEthernet1/0/48
description UPLINK from Core
switchport mode trunk

do i need to add static route from my access switch to core switch?

thanks to anyone who can help me sort this out.

more power to all!

[balaji.bandi]

This may be due to STP i guess, Make sure your Core Switch 3850 have higher ATP priority

what is the logs you see omn both the devices ?