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Dual Data Center routing/load balancing question

Customer has come to me with an interesting routing / load balancing question.


Large MPLS cloud to 50+ remote Branch locations with two Data Centers, A and B.

The PE routers in the cloud at each branch has connections to bothe Data Centers.

The PE routers are configured to see equal cost paths to the two Data Centers.


The Data Centers have Dark Fiber between them and they have the Server Vlan 172.16.10.x available at both sites.

ServerA is in location A and Server B is in location B

They will have HSRP on the gateway routers in location A and B with the RouterA being the primary.



The customer understands from the Branch we can load balance stream by stream traffic back to the Data Centers to use under normal conditions.  What they are concerned is that all return traffic is going to go out through RouterA.

Looking for some way that we can load balance out bound traffic from the Data Centers so that traffic from ServerA will go out RouterA and ServerB will go out RouterB, but failover seamlessly to the other location.

Moving ServerB to a different Subnet would be the option of last resort.


Does anyone have any thoughts?

4 Replies 4

Dennis Mink
VIP Alumni
VIP Alumni

OSPF can do equal cost load balancing, still your requiremeny is unusual. from your server subnet you would have one default gateway only , so you would have on router making a routing descision, and would not load balance, unless you put a layer 3 boundery between your server subnet and WAN. can you share a pic of your topology including routing?



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It seems to me if u have HSRP so outgoing traffic will always prefer to go via active node which is Router A , so even if u send traffic to them via both router A and B load balancing return traffic will go via router A .  As I remember even manipulating with ospf /eigrp metrics/cost will not help in case of HSRP. 

Jon Marshall
Hall of Fame
Hall of Fame


MHSRP so each server uses it’s local router as it’s default gateway. 



Level 1
Level 1

For HSRP, you can try creating a second HSRP group and using it as a default gateway for half of your devices. You can refer to the following for more information:



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