MPLS TE and DS-TE Design for Enterprise Networks – Part 1


Business Drivers & Technical requirements
As part of business requirements to optimize bandwidth utilization and differentiate internal and external customers traffic flows across an aggregated transit environment such as MPLS Core backbone we define a MPLS TE solution with automated TE tunnels provisioning along with capability of MPLS TE to route traffic based on EXP value, DiffServ Traffic Engineering. We also define the incumbent MPLS DiffServ techniques such as MPLS VPN QoS Models to remark customer traffic flows at ingress.
Below is outlined the different design approaches to select the proper TE solution for the customer (Keep in mind business drivers are factors of the business segment of the customer. Therefore the business requirements are unique per customer even though there are many similarities when it comes to technical requirements among distinct network environments.)
1. MPLS TE and MPLS DiffServ – Deployed where differentiation and optimization are required
1.1. Per-VRF Tunnel Selection – With this technique we will provision manual TE tunnels with path protection and FRR with Link/node protection from PE to PE and forward high priority traffic (Trading VRFs) on these tunnels. Low priority traffic (Non-Trading VRFs) will flow following the Link-State Topology. This solution will require a QoS architecture describing admission control at the ingress and MPLS DiffServ through the MPLS Core. This increases the operational complexity of the network and reduce its scalability. We should probably look into a method to automate the provisioning of the TE tunnels.
1.2. Auto-mesh and LDP tunneling – LDP enabled on the links between PE and P routers, auto-mesh tunneling between P routers with LDP tunneling between PE routers. Admission Control and MPLS DiffServ will differentiate Customer traffic respectively at the ingress PE and on ingress P routers. We will also rely on CEF for traffic load balancing on the LDP links. This solution provides some limitations when it comes to Traffic Engineering Service differentiation as each VPN packet will have the same fate from TE forwarding perspective.

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