Pain Area and aspects for consideration:
- If Last mile goes down frequently?
- MPLS Backbone issues with one Service Provider?
- Will it be a cost effective solution?
- Up to what level of redundancy and uptime commitment?
- Where is the Single point of Failure?
- Will both the circuits run parallely?
- What 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 2 CPE’s?
Solution Discussion
This is the scenario where customer can ensure better uptime and high availability with load sharing 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 2 different CPE’s for better redundancy. 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 multi-homing 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. CPE Router should have minimum 1 Routed port along with 1 LAN port with all the routing features enable on to it.
So in respect of solution recommendation is to run eBGP as a Routing protocol between CE-PE at WAN Side with Attributes and iBGP between both the CPE’s, for LAN side customer have to break their LAN segment into 2 different parts because one LAN segment would be advertise to one 1st ISP MPLS link and other to 2nd ISP MPLS Link.
Technical Arrangement -:
- Topology Support – Hub and Spoke or MESH Topology.
- Recommended eBGP routing protocol in between CE-PE.
- There will be 2 LAN segments which would be advertise separately to both ISP’s MPLS Link.
- Configure different group for each subnet in HSRP/VRRP in LAN segment and users will configure Virtual IP address as default IP address of their gateway.
- All CPE’s will advertise half LAN subnet in BGP to ISP1 and half LAN subnet in BGP to ISP2.
- All CPE’s will advertise supernet subnet in BGP to ISP1 and ISP2.
- Configure IBGP between both the CE Routers.
- 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.
