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IP/MPLS Network Architecture

nunoscosta
Level 1
Level 1

Hi guys,

 

I have 3 questions regarding IP/MPLS architecture.

1. Let's consider one network "hub and spoke" with 200 "spoke" sites that are connected with 9 core sites (each remote is connected with 2 core sites for HA) to reach 2 "Hubs".

The network layers are CORE (PE Routers only), Edge (Costumer Edge Router) and Access (LAN).

It is relevant to consider P Routers? What are the main concerns?

 

2.This private network, will be changed to the following:

. Each PE Router will be configure as P Router

. Each Costumer Edge Router will be configure as PE Router.

What are the advantages in that, regarding O&M, security, costs?

 

3.What are the best practices regarding tunnel span?

 

Thank you very much for your knowledge!!!

Regards,

NC

 

1 Accepted Solution

Accepted Solutions

I think theses are both valid designs. There is no right or wrong. And I probably would need much more insight into the situation and requirements of that company.
But I would normally go with the P - PE design with no CE routers. It has one tier less in the architecture and adds a lot of MPLS functionality in the branches. But you need to spend money on advanced ip services licenses, unless you have them anyway.

Also it is the less complex design from my point of view, since all branch routers are configured the same way and there is no cascading of sites.

But it really all depends on your requirements. I guess you have some virtualization requirements, since you're using MPLS for your corporate network. If you have a requirement to run different VRF's in a branch, then having PE's in the branch is definitely a good choice.

- Markus

View solution in original post

4 Replies 4

Markus Benz
Level 1
Level 1

Hi Nuno,

I am not a 100% sure what exactly you want to know.
But I try to answer your question.

The main benefit of having a PE router in a enterprise branch is virtualization. You can configure VRF's in the branch. If you have several VRF's that you need to run within a site, this might be beneficial to you. Downside is clearly licenses required for MPLS (correct IOS version) etc.

As for the core, the difference between P and PE is that P routers only run MPLS and an IGP. No BGP and no VRF's are configured on these routers. They only forward traffic within the core. You actually don't need to touch them, unless you add a new PE router or you upgrade IOS etc.
A PE router runs BGP and VRF's etc. so there is much more need to configure something on them if you add sites etc.
Depending on the platform you run, it could also be a performance issue. Since your only run a minimum of protocols on P routers, the are very stable and performant.
So a P router based core, maybe adds some stability over what you have today.

I don't know exactly what the motivation is to change you'r environment to a P - PE based setup, instead of PE - CE based. But I don't see any problem with it. With a large customer with a lot of virtualization requirements, I would probably do the same. Would be interesting to understand the background here. Probably I can give you a more precise answer then.

What exactly do you want to know regarding the "tunnel span"?

Regards,
Markus

 

Hi Markuz,

 

Thank you very much for your answer.

The main question here is, where should you terminate the LSP or MPLS domain?

On the PE, or CE routers?

If you configure the CE to be PE router then you don't need the atual PE routers (aggregation nodes) doing BGP peering, because they only need to transfer the data faster. In this case P routers should be the best configuration.

You can check the attatchment to understand the concerns.

 

Tunnel Span is about MPLS domain reachability, where should i terminate the labeling?

sorry my english :)

best regards,

Nuno Costa

I think theses are both valid designs. There is no right or wrong. And I probably would need much more insight into the situation and requirements of that company.
But I would normally go with the P - PE design with no CE routers. It has one tier less in the architecture and adds a lot of MPLS functionality in the branches. But you need to spend money on advanced ip services licenses, unless you have them anyway.

Also it is the less complex design from my point of view, since all branch routers are configured the same way and there is no cascading of sites.

But it really all depends on your requirements. I guess you have some virtualization requirements, since you're using MPLS for your corporate network. If you have a requirement to run different VRF's in a branch, then having PE's in the branch is definitely a good choice.

- Markus

Hi Markus,

 

You clarify all my doubts.

Thank very much for your answers.

 

regards,

NC

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