11-06-2013 07:57 AM - edited 03-04-2019 09:30 PM
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.
11-06-2013 10:00 AM
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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.
11-06-2013 10:27 AM
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% |
11-06-2013 06:48 PM
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.
11-07-2013 12:00 PM
You need to account for the IPSec overhead.
The table was populated with the 'show int' and 'show proc cpu' outputs.
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