Etherchannel within same C3850 switch stack

[Cinco F Smartnet-Tac]

Hello

due to some singularities (riverbed implementation), we need to configure an Etherchannel within the same C3850 stack. Schema is below:

1/0/4 (C3850) ----- lan0_0 (RB) / wan0_0 (RB) ------ 1/0/7 (C3850)
2/0/4 (C3850)----- lan0_1 (RB) / wan0_1 (RB) ------ 2/0/7 (C3850)

1/0/4 and 2/0/4: L3 etherchannel

2/0/7 and 2/0/7: L2 etherchannel vlan 230

Does anyone know if this is possible?

Thank you

Marcos

[Francesco Molino]

Hi Marcos

What's your question? Is it related to design or configuration? 

In terms of config, you can do both on your 3850. 

I'm not very familiar with riverbed, but others like barracuda have quite the same design. It's for in-path and out-path. 

Is your vlan 230 your outside subnet? 

Thanks 

PS: Please don't forget to rate and select as validated answer if that answered your question

[Cinco F Smartnet-Tac]

Hi Francesco

actually is both design and configuration.

We configured that topology and it worked, but 3 days later the network got unstable.

Initially we thought it could be the Riverbed, but when we removed it from the stack, the issue persisted what caused some doubts if an etherchannel can really be configured within the same C3850 stack.

Vlan 230 is an outside subnet where I have 2 firewalls (HA mode) connected.

config is below:

ip route 0.0.0.0 0.0.0.0 10.95.64.201
!
interface Port-channel11
description *** CHANNEL TOWARDS LAN RIVERBED ***
no switchport
ip address 10.95.64.202 255.255.255.248
speed 100
duplex full
spanning-tree portfast
!
interface Port-channel12
description *** CHANNEL FROM WAN RIVERBED ***
switchport access vlan 230
switchport mode access
speed 100
duplex full
!
interface GigabitEthernet1/0/4
description ## TO LAN0_0 Riverbed ##
no switchport
no ip address
speed 100
duplex full
channel-group 11 mode on
spanning-tree portfast
!
interface GigabitEthernet2/0/4
description ## TO LAN0_1 Riverbed ##
no switchport
no ip address
speed 100
duplex full
channel-group 11 mode on
spanning-tree portfast
!
interface GigabitEthernet1/0/7
description ## TO WAN0_0 Riverbed ##
switchport access vlan 230
switchport mode access
speed 100
duplex full
channel-group 12 mode on
spanning-tree portfast
!
interface GigabitEthernet2/0/7
description ## TO WAN0_1 Riverbed ##
switchport access vlan 230
switchport mode access
speed 100
duplex full
channel-group 12 mode on
spanning-tree portfast

[Julio E. Moisa]

Hi

Remove the spanning portfast and set up the speed as auto. 

[Cinco F Smartnet-Tac]

Hi Julio.

I will. Besides that, do you believe that this design has something incorrect?

thank you for helping

Marcos

[Julio E. Moisa · Accepted solution]

Hi,

Nop, at simple sight everything looks fine. You can also evaluate to change the mode to be used with LaCP instead on both switches. 

[Francesco Molino]

Hi 

Except what Julio said, nothing special. Maybe you can also change your port-channel in lacp as riverbed support that. 

However, what kind of instability you had? 

Maybe nothing related to your new po?

Did you took some debugs or logs or whatever to share? 

Thanks

PS: Please don't forget to rate and select as validated answer if this answered your question

[Cinco F Smartnet-Tac]

Thank you Julio and Francesco.

when the network got unstable some devices were reachable and some not from other sites. When the etherchannel within the stack was removed, all of devices were reachable.

I will reproduce the issue in a lab and then inform you guys about the results.

Thank you both for helping

Marcos

[Francesco Molino · Accepted solution]

Maybe there was a missconfiguration somewhere and you faced STP issue but without logs it would be difficult to say what and where. If you can reproduce that in LAB, we can help you in troubleshoot and figure out what's going on.

Thanks

PS: Please don't forget to rate and select as validated answer if this answered your question

[Cinco F Smartnet-Tac]

Hi Julio and Francesco

we configured the etherchannel as LACP and we have not had any issue since then.

Thank you very much for your help

Kind regards

Marcos

[Julio E. Moisa]

Hi

Im glad to hear that. Thank you for the update.

Have a great day

:-)

[Francesco Molino]

Hi

Glad that everything is good.
If you need any help, let us know

[Julio E. Moisa]

Hi

Im not really sure about the question, but you can have 2 separate ether-channel on the switches but you cannot have the same etherchannel working as L2 and L3 at the same time, they need in different groups. But you need to group at least 2 interface for each group to take advantage of Etherchannel. 

Hope it answered the question.

:-)