Agenda
How to achieve Active/Active Internet Traffic load balancing along with High availability using single ISP via diverse physical path.
Scenario
Two DC’s with different ip subnets running and requires active/active internet load balancing for inbound and outbound along with high availability in case of failure of any of the physical connection failure in DC’s.
Limitation
- Don’t Have public AS number
- Reduce cost by involving multiple ISP
Schematic
Diagram attached for information
How to Achieve
BGP AS prepend path is one of the powerful attribute which is used to achieve the above requested task.
ISP has provided two separate public subnet for both the DC’s for service publication with Active/Active fashion.
Subnet a.b.c.d for DC1
Subnet e.f.g.h for DC2
ISP vendor X is having two connection outlet on both the DC’s via separate physical paths and giving a ethernet handoff at each DC’s.
Run BGP with ISP X from both DC’s Routers and send DC1 subnet a.b.c.d with normal metric and DC2 subnet e.f.g.h with as prepend path to ISP X DC1.
Note :- To have min. size of routing table , Have only default route from ISP X from both the DC’s BGP handoff.
Run IBGP between DC’s customer managed routers so that both can exchange respective public ip subnet as well default routes published by ISP X at both the DC’s.
Do the same level BGP configuration at DC 2 by AS path prepending DC 1 subnet and sending DC 2 public ip subnet with best metric.
Benefits
- Two active outbound connection from both DC’s
- Two active Inbound connection from both DC’s
- In case of failure of DC1 physical link or switch or ISP X router or Cable , Via IBGP DC1 subnet will still be reachable vis DC2 connection to internet world and traffic from internet will also be reachable to DC1 subnet via DC2 connection
I hope the above material is bit informative and useful ...
-GI