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Community Member

MPLS and CPU utilization !

Hi every1, this query could be a bit long but kindly read it, its very imp. I have a 3845 router running 12.4 20T, with 64 flash and 512 ram. Its utilization on average is 52% !!. This router is the DMVPN hub for 40 branches, other branches are coming through other P2p links. The number of branches is 160. The hub router is also connected to internet and from the entire country the traffic lands on this router to reach internet and other branches for data connectivity. On this 3845 i just have onboard encryption card and no AIM or other modules. Now an evaluation team proposed us that if we run MPLS in our environment with our ISP we will achieve the following

1) More guaranteed and end to end QOS for mission critical applications.

2) Bandwith management will be better

3) CPU utilization will drop.

For point 3) they said that due to use of gre tunnels router has to do a lot of fragmentation which results in high cpu load !!.

I am seeking advice from you experts kindly guide me, is it wise to run mpls in my bank ??? how will it benefit me ? shall i really go for it ? i think mpls is very complex to configure and understand so what you guys think. Pls provide me some basis so that i may know whether its really gonna be helpful or a burden ??

Thanks in advance


Re: MPLS and CPU utilization !

I donot think so you require the MPLS. Becasue it is more towards the service provider network. You can ask your SP to provide you the MPLS connectivity.

Even without configuring MPLS in your network you can acheive all the above mentioned points. You can ask your service provide you to provide all the things definately he will be going to charge you. BGP is the best Protocol in case of PE-CE link.


shivlu jain


shivlu jain

Hall of Fame Super Silver

Re: MPLS and CPU utilization !

Hello Ovais,

I agree with Shivlu:

if you buy an MPLS L3 VPN service the MPLS provider can give the equivalent of leased lines to branch offices and you can save cpu resources by performing routing without any form of tunneling and by having a single neighbor the PE router instead of 40 to 160 spokes of an overlay model.

This makes the difference.

This certainly provides cpu savings but you need to pay more for the MPLS service.

This doesn't mean you are going to run MPLS services on your routers.

Hope to help


Community Member

Re: MPLS and CPU utilization !

Hello Illusion,

We just changed to MPLS for our branches ( bank also) and it is nothing more than BGP between the PE and the CE. The MPLS is good, in that the BGP is a better protocol than Frame Relay and RIP which is what we had before. However non of these improvements will work properly without proper COS coordinated with the provideer, and proper QOS on your network. Cisco Works has a really cool QPM module. and if you have any high end routers like 7200 or even 2811, they can do NBAR. You will also have to have a valid sniffer product, because physically your topology will most likely go from a star to a fully meshed. which will aslo have an effect on your voip. You will realy have to have your finger on the traffic as far as QOS goes.

other than that is is a nice easy migration and you should be happy. Dont forget about the transit AS, rule if you have more than one provider. lastly , that 3845 sounds like it might be struggling a little, even not considering the fact that you have to segreagate your traffic types, simpley by the sheer volume of traffic. Good Luck.

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