Which router to use for 100Mbps download and 20Mbps upload?

[bfpnetworking]

                   I need to upgrade one of our locations to a 100Mbps download/20Mbps upload circuit.

Which Cisco router should I use to meet the speed requirements?

The router handles basic NAT rules for email and VPN.  No special configuration other than that.

I have had vendors recommend a cisco 1921, 1941 and even 3900 series 9which seems like overkill).

Any thoghts/suggestions would be appreciated.

[Joseph W. Doherty]

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In the attached documented, for 120 Mbps of aggregate bandwidth, the closest Cisco recommendation would be for a 2921 (50 Mbps, duplex) or a 2951 (75 Mbps, duplex).

Assuming your usage is lighter than 100% utilization, in both directions, you can downsize for your expected usage.  Although realize your router may struggle, and performance suffer, when dealing with sustained bursts of traffic.

[Edison Ortiz]

Packet size does matter and VPN will demand more power.

Here is some testing I did earlier this year on 3945 ISR G2

3945	Onboard VPN
	Packet size / Bytes	Input Rate / bps	Input Rate / pps	Output rate / bps	Output Rate / pps	CPU
	512	13144000	3000	13144000	3000	25%
	512	21916000	5000	21916000	5000	36%
	256	15180000	6500	15175000	6500	45%
	256	23356000	10000	23356000	10000	65%
	128	15743000	12001	15744000	12001	76%
	64	12004000	15005	12004000	15005	91%
	64	14397000	17996	12687000	15860	96%

[Joseph W. Doherty]

How's your bps computed?

I.e. 512 bytes * 8 bits/byte * 3,000 pps = 12,288,000 bps or 64 bytes * 8 bits/byte * 15,005 pps = 7,682,560 bps.

[Edison Ortiz]

You need to account for the IPSec overhead.

The table was populated with the 'show int' and 'show proc cpu' outputs.