2 Service Provider MPLS Network on single CPE: Active-Active

Pain Area and aspects for consideration:

• If Last mile goes down frequently?
• MPLS Backbone issues with one Service Provider?  
• Should customer takes 2 different Service provider MPLS for all the locations?
• Will it be a cost effective solution?
• Up to what level of redundancy?
• Where is the Single point of Failure?
• Which Routing protocol needs to be run between CE-PE?
• What would the default-gateway IP address?
• How many ports required to connecting 2 Service Provider in Single CPE?

Solution Proposed :

This is the scenario where customer can ensure better uptime and high availability with load balancing feature on MPLS Network from 2 different Service providers, in this case study take 2 separate MPLS Network from 2 different Service Provider at each location either on HUB and Spoke or Mesh Topology and terminate into single CPE (Dual Power). Most of failure happens at Last mile end of the Service Provider which leads to high down time and less availability of the mission critical sites which affects business processes. Customers have to make sure that both Service providers offer their own last connectivity at every location unless if any last mile connectivity goes down that site would be down and isolate from the network because both the Service providers are different but the last miles they are using are same. This scenario also called Load sharing with multiple service providers. By configuration on CE and PE end at both the service providers, customers can have active-active scenario (Load sharing) where half of customers LAN traffic will move through one Service provider and rest of the customers LAN traffic will move through other Service provider in ideal scenario and if any location goes down traffic will reroute automatically on active Service provider and users would experience seamless connectivity at their end without any manual intervention. There are different ways to achieve this but the best way in terms of solution recommendation is to run eBGP as a Routing protocol between CE-PE at WAN Side with Attributes, for LAN side customer have to break their LAN segment into 2 different parts because one LAN segment would be advertise to one 1^st ISP MPLS link and other to 2^nd ISP MPLS Link for load sharing.

Technical Aspects:

1. Topology Support – Hub and Spoke or MESH Topology.
2. Recommended eBGP routing protocol in between CE-PE.
3. There will be 2 LAN segments which would be advertise separately to both ISP’s MPLS Link.
4. All CPE’s will advertise half LAN subnet in BGP to ISP1 and half LAN subnet in BGP to ISP2.
5. All CPE’s will advertise supernet subnet in BGP to ISP1 and ISP2.
6. In ideal scenario CPE will always choose most specific route towards destination and whenever any link goes down in that CPE will prefer supernet to reach that destination.
7. Multipath in BGP can also be configured for Load sharing but traffic will be asymmetric.
8. Routers should have minimum 2 Layer 3 port + 1 Layer 2 port.
9. Routers should support all the Routing protocol along with tracking command.