Service Provider Design-Seeking-suggestion

Routing & Switching MPLS
2

Hello Maheshwaran

I will attempt to respond to each of your questions.

  1. It is possible to have a network design with only PE routers and no P routers. However, this is typically seen in smaller networks. If you have, say 5 routers, you can easily avoid using P routers, however, if you have 100 routers and try to avoid P routers, you can quickly see how that will be difficult, and expensive (many links between PE routers) and it won’t be very scalable.
  2. Yes, PE routers can act as Route Reflector (RR) routers. But it’s not a common practice as it could lead to performance issues. It’s generally better to use separate devices for these roles to distribute the load. Also, RRs should typically be located as close to the center of the network as possible, and PEs by definition are on the edge.
  3. It depends. Technically, both PE and P routers can connect to IGW routers. However, by connecting a P router to the IGW, by some definitions, you make it into a PE router!
    Best practice dictates that only PE routers are the ones that connect to the IGW as they are at the edge of the service provider network and handle customer traffic to and from the internet.
  4. Not having P routers in your service provider design is not recommended in general except for very small networks, which you wouldn’t typically see in an ISP. P routers help in reducing the complexity of the network by limiting the number of iBGP sessions and allowing PE routers to focus on handling customer traffic.
  5. The placement of RR routers depends on the size and design of your network. In general, it’s better to place RR routers closer to the center of the network to reduce the number of hops and ensure better connectivity. However, in a very large network, you may need multiple RRs, some of which could be placed closer to the border.

Remember that these are general suggestions and the best practice for your specific network might vary depending on various factors such as network size, traffic patterns, hardware capabilities, etc.

I hope this has been helpful!

Laz

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