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Ask the Expert- SD-WAN

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Beginner

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

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)#

Everyone's tags (2)
1 ACCEPTED SOLUTION

Accepted Solutions
VIP Advisor

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

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

 



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future
5 REPLIES 5
VIP Mentor

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

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.

Beginner

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

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
!

VIP Advisor

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

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

 



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future
Beginner

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

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"
!

VIP Advisor

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

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



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future
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