Choosing PE-CE Routing protocol

When it comes to choosing your PE-CE routing protocol, Which one do you think is best?

Choosing the PE-CE routing protocol for MPLS VPN  is an ongoing debate between back end network teams and those who have customer interface roles. They are always trying to satisfy the customer and we are always trying to keep the network simple, clean and stable.

To approach this issue we have to look from different perceptual views, as customers and service providers, as customer interface engineers and back end engineers. We need to see the big picture and work on a WIN-WIN solution.

The role of the PE-CE routing protocol is to exchange routes between the customer's site and the provider's routers. The received routes are then converted to VPNv4 routes and distributed using MP-BGP to the rest of the network. This routing exchange operation happens between different networks or autonomous systems (Customer, SP networks) which makes BGP the best fit for such relation.

From the provider perspective we need to keep the network as clean as possible. One way to this is running the minimum set of routing protocols. Increasing the number of running protocols on the provider's network is undesirable for many reasons, some of them are listed below:

  1. Increases the possibility of hitting bugs. Network Stability suffers from bugs.
  2. Need for network OS that supports more features. This may require regular maintenance or upgrades to cope with different customers' requirements.
  3. Harder troubleshooting for operations teams and problems is expected to take longer time to be solved.
  4. Its harder to maintain in a Multi-Vendor environments, because of proprietary protocols or features.

Taking in consideration the previous points the provider will always prefer running BGP as a PE-CE routing protocol because BGP is mandatory in service provider networks so they are already running it.

The customer may have a different point of view and other considerations as follows:

  1. The customers are usually trying to run something they are comfortable with. Most IT departments in small to medium size enterprises are not comfortable running BGP.
  2. The customers do not want to add a new protocol to their networks for reasons like they have small routers and these routers do not support BGP or because this may require some configuration changes to their networks.
  3. This may be also for other myths about BGP or assuming the BGP is going to slow their network convergence in case of failures. "There are a lot of features to improve convergence time if this is really a big concern".

Both sides have their own justifications, but again if we consider the big picture we will see that running BGP benefits both the customer and the provider. BGP offers full control for both sides on routing updates and traffic policies. Customer will have his problems handled faster and by highly skilled engineers. BGP is the heart of the internet and you will find full support from vendors and service provider.

I believe that BGP is the best PE-CE routing protocols. We will explore the configuration and best practices part of this issue in coming posts.

Please make sure to post your experience about this topic  and help us to finalize this debate :)

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