Attached file is drawing, and below is the current config of link that is already up. I need to add another fiber redudnant link between 6509 and 2960 stack. Please help me on config Spanning side by not taking 6509 down after the change. 6509 is in distribution.
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X-ALPHA-IDF-1FORMS-2960S-0# (SIDE)
!
interface GigabitEthernet1/0/52
description X-ALPHA-F-6509-0 uplink
switchport trunk native vlan 18
switchport mode trunk
srr-queue bandwidth share 1 50 30 19
priority-queue out
mls qos trust dscp
macro description cisco-router
auto qos trust
spanning-tree portfast disable
spanning-tree guard loop
ip dhcp snooping trust
!
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X-ALPHA-F-6509-0# (SIDE)
!
interface GigabitEthernet3/10
description 1st floor POC2 Forms IDF
switchport
switchport trunk encapsulation dot1q
switchport trunk native vlan 18
switchport mode trunk
no ip address
mls qos trust dscp
spanning-tree guard loop
!
