Meraki Hub DC-DC routing behaviour

[nunop]

Hi,

I'm studying this scenario for a possible implementation of One-Armed Concentrator mode - Datacenter Redundancy (DC-DC Failover) which I think is quite similar to (scenario 3) https://documentation.meraki.com/MX/Networks_and_Routing/Border_Gateway_Protocol_(BGP)#Scenario_3:_D...

only adding the HQ as the internal network we want to reach from the spoke.

Given the below diagram I think we will have an asymetric routing in case priority hub of the spoke = DC-B, because the return traffic will get preference via DC-A (primary DC) and traffic will get eventually blocked by the DC-A statefull firewall.

My question is if there is someway to influence the Hub to Hub tunnel to be preferred (green arrow) with for example lower administrative distance to be preferred over eBGP or this is not possible to tune? Or any other thoughts?

Thanks!

[ww]

If your spoke has DC-B as first hub.

The DC-A HUB would do as Prepend 2x the AS number. HQ would choose DC-B as preferred (shorter) return path. 

You want force all traffic to DC-A for a reason from the HQ?

And why not set spoke to prefer DC-A?

[nunop]

The problem is that I have the traffic heavly AS prepended at the HQ via side B and additional prepend on side A won't make any change, just trying to see the options I have, so it seems hub to hub tunnel is not an option to consider, right?

Yes the spoke via A works fine but I'm checking if we go via B it works or not.

Thanks

[PhilipDAth]

I would be very nervous about this unless I could have a stretched VLAN between the two DCs, and to be able to turn the firewalls into a clsuter.