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ISR 4451 Question


I have a question on the ISR 4451. Customer would like 10GE and ISR 4451 does support 10GE for the SFP module but in terms of performance, it support 1Gbps and upgradeable to 2Ggps.  


See this chart for the performance information on the 4451:


Does this  mean that the router will not be able to process 10GE at all due the the performance limit at 1Gbps (at default).  Will there be a bottle neck if the network interface starts sending/receiving traffic at 10Gbps?


Thank you in advance,


5 Replies 5

Joseph W. Doherty
Hall of Fame Master Hall of Fame Master
Hall of Fame Master
My understanding is the ISR 4K series have an internal "throttle" to limit the device's aggregate performance. It should work much like a shaper.

So I would expect if you have a 10g interface, over some time period, it shouldn't forward more data than a gig or two gig interface would for that time period. However, individual frames/packets should transmit/receive at 10g. If the 4K series works as I expect, what I wouldn't know is what "Tc" would be used.


Hi Paula,


You may want to check the below document. The limitations advertised (1Gb upgradable to 2Gb) are under normal operation with common features on. Depending on what features you intend to use the speeds may be higher or a lot lower than the platform limitation (e.g. WAAS)


A 4451 which I saw in production with a 1Gb internet circuit was doing fine but not great at around 800-950Mbps with NAT, QoS and ZBFW on. Keep in mind to take into account the upload and download when thinking at the platform limitation.


I would not even dream at thinking to have anywhere near 10Gb sustained throughput. So if the client whats 10Gb for the sake of 10Gb make sure you include the platform limitations as a bullet point. Alternatively ASR1001x is your next bet with upgradeable 2.5 to 5,10, and 20 Gbps and 2 x 10Gb slots.


Hope it helps,



Leo Laohoo
VIP Community Legend VIP Community Legend
VIP Community Legend
It means that the entire chassis, and not per-port, can support 1 Gbps and software upgradeable to 2 Gbps.
A router that can push >10 Gbps is the exclusive domain of the ASR.

Thank you so much everyone for responding.


The 4000 series routers have built in shapers that limit the throughput to that of what a combination of the hardware and license you have can handle. So to answer your question, yes there will be a bottleneck at the router if you are attempting to send 10Gb through it.  See the link below for real world throughput testing results.




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