We have above network and here is the cisco trunk configuration.
Nexus 5548
interface Ethernet1/9
description F5-10G-Link
switchport mode trunk
switchport trunk allowed vlan 201
Cisco 3850 (non-root switch)
interface Port-channel20
description F5-2G-Etherchannel trunk
switchport trunk allowed vlan 201
switchport mode trunk
end
interface GigabitEthernet1/0/45
description F5-1G-a
switchport trunk allowed vlan 201
switchport mode trunk
channel-protocol lacp
channel-group 20 mode active
end
!
interface GigabitEthernet1/0/46
description F5-1G-b
switchport trunk allowed vlan 201
switchport mode trunk
channel-protocol lacp
channel-group 20 mode active
end
links are up but if i check in STP configuration on cisco my 10G link is in blocking mode and 2G link is forwarding mode, as per STP cost calculation 10G link should be in forwarding because it has total cost to reach root is 4 and 2G link total cost to root is 5 right?
Even i tried to increase spanning-tree cost of 2G link but it didn't work still that link is in FWD mode.
SW2#sh spanning-tree int po20
Vlan Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
VLAN0201 Desg FWD 3 128.2046 P2p
Nexus#sh spanning-tree int e1/9
Vlan Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
VLAN0201 Altn BLK 2 128.137 P2p
If i am trying to shutdown 2G trunk then on Nexus switch i am seeing following spanning-tree status which is weird
Nexus# sh spanning-tree int e1/9
Vlan Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
VLAN0201 Desg BKN*2 128.137 P2p *LOOP_Inc
and this interface never come into forwarding state.
what i am doing wrong here? is my cisco config is wrong on trunk?
EDIT
In f5 side we have default STP setting which is "Passthrough", Should i change it to RSTP?
spanning-tree mode rapid-pvst