Bandwidth Issues on Cisco 1921 v15.5

[CarsonDavis56998]

Hello, I have just connected a Cisco 1921 Router to a 1G Circuit, however, when running a speed test behind the router I can only get up to 170-190Mbps. On the router, I have the minimum features and configurations enabled to try to see was it some of the configurations such as DMVPN, IPSec, OSPF, and a list of ACL's I built causing the router to bottleneck but it seems that was not the issue. I have seen many posts stating that this is normal behavior from this model router. However, I am having a hard time understanding why would cisco advertise that this router can support 2770 Mbps throughput but can cant get anywhere near that in a production environment. Does anyone have an idea and could possibly fill me in, or is there a license needed to enable higher speeds? Also, are there any routers out there that can support 1G total throughput that anyone would recommend? Thanks!

Additional notes:

- I have tried setting Speed @ 1000Mbps and Full-Duplex on both sides but still no luck

- I have confirmed that CPU utilization stays under 10%

- There are no CRC/Input errors on the WAN port

[Joseph W. Doherty · Accepted solution]

There's a bunch of conditions to obtain the 2.7 Gbps; generally not possible in the "real world".

Cisco also provides a recommendation of using the 1921 for up to 15 Mbps WAN circuits.

The fact you say you don't see the CPU go above 10% should imply the router's CPU isn't the bandwidth limiter cause.

Could you explain/expand on the physical WAN topology?

[CarsonDavis56998]

Thanks for the response  @Joseph W. Doherty. Currently, the topology is very simplistic as I have already removed many appliances in front and behind my router to better focus on the BW issue.

As of right now, there is only a Broadband DIA circuit that then feeds to my Cisco 1921 router. The Broadband circuit has been verified and has speeds of almost 950Mbps. Furthermore, the circuit is in passthrough mode, so nothing like Firewall features and web filtering is enabled. Let me know if there is anything other information I may provide. Thanks!

[Joseph W. Doherty]

950 Mbps both up and down?

[Leo Laohoo]

Agree with @Joseph W. Doherty .

1921 is not designed to do 1 Gbps work.  

For home use, maybe 150 Mbps but put it in an Enterprise environment and it will have an average speed of 15 Mbps.

[Joseph W. Doherty]

"1921 is not designed to do 1 Gbps work."

That's for sure, although if CPU not exceeding 10% usage (which seems low for 100 Mbps on that router), I would suspect there's some other issue, often on the "WAN" side, but we're still lacking for information.