Flex Link (switchport backup) IOS 3.x to 16.x

[ampdog]

I have a WS-C3650-48TD Catalyst switch running IOS 3.06.04 configured using Flex Link. When I try to use the same configuration on a switch running IOS 16.3.7 the command is not there under the interface. see below...

Is there another way or technique to do Flex Link or create a backup truck on IOS 16.x?

Cisco IOS Software, IOS-XE Software, Catalyst L3 Switch Software (CAT3K_CAA-UNIVERSALK9-M), Version 03.06.04.E RELEASE SOFTWARE (fc2)

ROM: IOS-XE ROMMON
BOOTLDR: CAT3K_CAA Boot Loader (CAT3K_CAA-HBOOT-M) Version 3.56, RELEASE SOFTWARE (P)

!
interface GigabitEthernet1/0/47
description CS1-NSwitch1 Dot1q Trunk
switchport trunk allowed vlan 3
switchport mode trunk
switchport backup interface Gi1/0/48
speed 1000
duplex full
no cdp enable
!
interface GigabitEthernet1/0/48
description CS2-NSwitch1 Dot1q Trunk
switchport trunk allowed vlan 3
switchport mode trunk
speed 1000
duplex full
no cdp enable
!

*****************************************************************

Cisco IOS Software [Denali], Catalyst L3 Switch Software (CAT3K_CAA-UNIVERSALK9-M), Version 16.3.7, RELEASE SOFTWARE (fc4)

ROM: IOS-XE ROMMON
BOOTLDR: CAT3K_CAA Boot Loader (CAT3K_CAA-HBOOT-M) Version 3.56, RELEASE SOFTWARE (P)

NSwitch1(config)#
NSwitch1(config)#interface GigabitEthernet1/0/47
NSwitch1(config-if)#switchport backup interface Gi1/0/48
                                                   ^
% Invalid input detected at '^' marker.

NSwitch1(config-if)#

[Georg Pauwen]

Hello,

the short answer is (from the release notes for 16.x):

Flex Links are not supported. We recommend that you use spanning tree protocol (STP) as the alternative.

[ampdog]

Thanks Georg!

Would you say that the simplest / best way to accomplish this is to increase the STP cost on the secondary port as below?

Or, with "spanning-tree vlan 6 root primary" and "spanning-tree vlan 6 root secondary" on the other 2 switches?

Thanks Again!

!
interface GigabitEthernet1/0/47
description CS1-NSwitch1 Dot1q Trunk
switchport trunk allowed vlan 3
switchport mode trunk
speed 1000
duplex full
no cdp enable

 !
interface GigabitEthernet1/0/48
description CS2-NSwitch1 Dot1q Trunk
switchport trunk allowed vlan 3
switchport mode trunk
speed 1000
duplex full
no cdp enable

spanning-tree cost 5000
!

[paul driver · Accepted solution]

Hello

If flex link isn't available then you can use EEM scripting so to have the port in a down state until the primary port goes down then EEM will bring the secondary port up when applicable.

If you want to manipulate the trunk via STP so that gig0/48 or its neighbor port is being blocked suggest you use spanning-tree port-priority xx  as this affects only the neighboring port and switch

Spanning-tress cost xxx will cause a recalculation to effect the entire stp domain for best path towards the root switch

[ampdog]

THANKS Paul!!

This worked perfectly.

!
event manager applet If_Primary_Trunk_Down trap
  event syslog occurs 1 pattern "Line protocol on Interface GigabitEthernet1/0/47, changed state to down"
  action 0001 cli command "en"
  action 0002 cli command "conf t"
  action 0003 cli command "int g1/0/48"
  action 0004 cli command "no shut"
event manager applet If_Primary_Trunk_UP trap
  event syslog occurs 1 pattern "Line protocol on Interface GigabitEthernet1/0/47, changed state to up"
  action 0001 cli command "en"
  action 0002 cli command "conf t"
  action 0003 cli command "int g1/0/48"
  action 0004 cli command "shut"
!

[paul driver]

Hello 
I am glad it assisted you and thank you for the rating.