4000 Series ISRs "Aggregate Throughput"

[jellybeanshiba]

Dear Community

I'm currently looking for a router platform, which should be used as a home gateway on 400 Mbps broadband access. Until now, my 880 Series ISR (C881-K9) has been working very well, but due to its limited line rate (100 Mbps), I'm considering to purchase a newer platform.

Since it'll be nice to have hands on IOS-XE, I studied the 4000 Series ISRs Data Sheet and found this strange term "Aggregate Throughput."

https://www.cisco.com/c/en/us/products/collateral/routers/4000-series-integrated-services-routers-isr/datasheet-c78-732542.html

Surprisingly, Cisco 4321, for instance, claims to have an aggregate throughput of "50 Mbps to 100 Mbps." What I do not get is, how is it possible that such expensive platform achieves only 100 Mbps in throughput? Even if no additional features except of routing were activated, the total throughput will be limited to 100 Mbps, right? I mean, even my tiny 880 Series ISR with activated PAT/CBAC/VPN achieves comparable throughput (somewhere around 96 Mbps) in routing. Even if the licensing model has been changed drastically after the transition to G2 ISRs, I personally cannot imagine anyone expecting less than a few hundred Mbps on those platforms.

Could anyone please tell me why that is so? or (hopefully), am I missing some of principales here??

Thank you very much for any comments and wish you a very pleasant day.

jellybenashiba

[Leo Laohoo · Accepted solution]

The replacement for the 800-series router is the ISR 1100.

If you're saying that the 880 can push >90 Mbps then why look at the ISR 4K?  There's got to be a reason, right? 

The 4K has a bigger NAT table, optional modules can be added, can support more VLANs than the 800 (among other things). 

When loaded, that's when the 4K bogs down to 50- to 100 Mbps.  

[jellybeanshiba]

Thank you very much for your reply. The reason I was considering ISR 4000 Series was because ISR 1100 Series was not yet very widely sold in my country (CH) and thus I couldn't find an attractive price.

> When loaded, that's when the 4K bogs down to 50- to 100 Mbps.

Does it mean that when not fully loaded, like without hundreds of VLANs, ISR 4000 should achieve higher throughput than those aggregate throughputs on the datasheet?

[Joseph W. Doherty · Accepted solution]

"Does it mean that when not fully loaded, like without hundreds of VLANs, ISR 4000 should achieve higher throughput than those aggregate throughputs on the datasheet? "

No, the ISR 4K platforms have a built-in software throughput limit. The limit is set such that a particular ISR 4K platform can almost always maintain that throughput regardless of traffic kind and/or router configuration.

Earlier ISR series throughput was whatever the CPU could support for the traffic mix and device configuration, which could vary very much.

[jellybeanshiba]

Thank you very much for your clear explanation :)