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L2 Etherchannel over 2 ISPs between two sites

dvrizhov
Level 1
Level 1

We are implementing the network design between the two sites (OLD Data center and NEW Data Center), scheme in attachement.

We have chosen this scheme on the following criteria:

- A single IP network between the sites (for simplicity migration);

- Fault tolerance via different ISPs.

But the problem is L2 etherchannel doesn't work correctly:

when one side port is shutting down, on the other side etherchannel will not rebuild and does not see that link down on the other end.

We have tried to use LACP in etherchannel (mode active on ports), but result was the same.

What may be the problem? Is it on the ISPs side?

Should we use this design or we have to subneting the network and make connections between the data centers classically with L3 channels and OSPF?

The configures of Core ports listed below:

OLD data center core (Cat 6509):

interface GigabitEthernet2/6

description #### TO DATA-CENTER core 1#####

switchport

switchport trunk encapsulation dot1q

switchport trunk native vlan 5

switchport mode trunk

logging event link-status

logging event trunk-status

logging event bundle-status

speed 100

duplex full

udld port aggressive

channel-group 2 mode on

end

!

interface GigabitEthernet2/7

description #### TO DATA-CENTER core 2#####

switchport

switchport trunk encapsulation dot1q

switchport trunk native vlan 5

switchport mode trunk

logging event link-status

logging event trunk-status

logging event bundle-status

shutdown

speed 100

duplex full

udld port aggressive

channel-group 2 mode on

end

!

interface Port-channel2

description #### TO DATA-CENTER core 1#####

switchport

switchport trunk encapsulation dot1q

switchport trunk native vlan 5

switchport mode trunk

logging event link-status

logging event trunk-status

logging event bundle-status

speed 100

duplex full

end

NEW data center core (Stack 2x3750):

interface GigabitEthernet1/0/1

description -- to MC-16R2-Core, port gi 2/6 --

switchport trunk encapsulation dot1q

switchport trunk native vlan 5

switchport mode trunk

logging event trunk-status

logging event bundle-status

logging event spanning-tree

speed 100

duplex full

udld port aggressive

channel-group 1 mode on

end

!

interface GigabitEthernet2/0/1

description -- to MC-16R2-Core, port gi 2/7 --

switchport trunk encapsulation dot1q

switchport trunk native vlan 5

switchport mode trunk

logging event trunk-status

logging event bundle-status

logging event spanning-tree

shutdown

speed 100

duplex full

udld port aggressive

channel-group 1 mode on

end

interface Port-channel1

description ### to MC-16R2-Core ###

switchport trunk encapsulation dot1q

switchport trunk native vlan 5

switchport mode trunk

logging event trunk-status

logging event bundle-status

logging event spanning-tree

speed 100

duplex full

end

I would be grateful for any advice.

1 Reply 1

Ivan Krimmel
Level 7
Level 7

Hi Dmitry,

I couldn't open the .vsd file, so I will just give it a try - I think having a L2VPN in that case would be beneficial, as you are trying to bridge two disperse segments via a 3d-party carrier.

HTH,

Ivan.

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