Router recomendation for a 100 Meg WAN?

[msaltissi]

Dear All

I really need help choosing a router to support a 100 Meg WAN.

It must be able to handle the full 100 Meg throughput at an MTU size of 1440-1500.

No need for modules or interface cards because I will use the onboard FE/GEs.

It will just be for routing and basic ACLs without any need for services, no encryption, no voice and no vpn.

Any help will be much appreciated.

Regards

Mark

[andrew.prince]

Mark,

Check out the below URL for "Realistic" thruput numbers.

http://www.cisco.com/web/partners/downloads/765/tools/quickreference/routerperformance.pdf

HTH>

[dsandre-toh]

that's an excellent planning document !

is there a similar document with encryption performance numbers? ie. max. encrypted thru-put, max tunnels ?

[msaltissi]

I found Miercom reports which has more details about Cisco routers and performance metrics.

http://www.miercom.com/?url=reports/&v=16&st=v

I checked out the Cisco Integrated Service Router Generation 2 May 2010 and I saw in Figure 3 numbers for encryption.

[msaltissi]

Cheers for that.

So please correct me if I'm wrong here.

My requirements are to provide a 100 Mbps of throughput for WAN IP traffic and I want to use both the router FE interfaces.

Its basic IP routing with no encryption.

According to the doc you sent me, to calculate the throughput using a 1500 MTU the following applies:

The calculation I used is (PPS x MTU x 8)/1000000 = Mbps

Cisco ISR2901 = 3924 Mbps throughput

Cisco ISR2911 = 4236 Mbps throughput

If this is the case then the 2901 will be more than ample for my requirements.

Does this sound right?

Ta

Mark

[paolo bevilacqua]

Just follow the reccomendations in the official Cisco document attached, and there is no need for calculations.

[hobbe]

Yes and absolutely NO !

As always there is never a strait answer.

yes that could be the way to calculate but most likely it is not.

Its very seldom that all your traffic matches the MTU size.

The MTU size is what that network part max can handle.

So if your traffic senders always packs a packet almost full then it would be a way to determin the router, but that just never happens.

Fx Imix traffic is most likely more accurate measurement to go by

If you can measure your traffic up and running somewhere then you will get the most correct result.

Then you will know "exactly".

So in short:

To calculate when YOUR 100Mbit/s router becomes overwhelmed you will have to use your traffic as a measurement tool.

if you calculate with to many large frames and your network uses alot of small frames then you might not get the performance you need in your network,

if you calculate with small frames then you will get the performance, but you might end up spending more money than necessary on hardware.

You want to ballance it all out to get the most bang for the buck. Thats what Imix is for.  its  a calculated value of what size of packets and % is sent over a "normal" internet network.

Good luck

HTH