We are using a Cisco FL-4330 for the first time. Our application requires Gbit throughput in one vlan.

According to the specification sheet, the Cisco FL-4330 only supports 100mbit in the backplane. The performance license increases this to 300 mbit.

Cisco's license model is very confusing to us. Could someone who is very familiar with these devices and the corresponding licenses confirm that no more than 300mbit throughput is possible?

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    Those are the hardware limits - with CEF + license, 2 Gbit/s in aggregate should be possible. Do you require specific router functions or just a basic router with Ethernet? For the latter, a simple L3 switch might be sufficient. – Zac67 Oct 19 '20 at 19:17
  • @Zac67: We're locked into this hardware by a customer. What we need is intervlan routing + possibly VPN. I'm not sure what you mean by CEF. If we can't make do with this router, we're going to add a switch. What exactly do you mean by "in aggregate"? – Fang Oct 19 '20 at 19:25
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    Inter-VLAN routing is fine with an L3 switch - do you require Gigabit VPN? Then the 4000 series won't work. CEF stands for Cisco Express Forwarding - fast, but with limitations, see Marc's answer. "in aggregate" means that no single port pair can reach that speed, only all ports together. – Zac67 Oct 19 '20 at 20:26
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    That is a router, not a switch, so it does not really have a backplane where forwarding is done in hardware. Running different services on a router can greatly slow the throughput on the router. For example, running encryption services will slow the router throughput to 10 to 15% of what it can do unencrypted. – Ron Maupin Oct 19 '20 at 20:28
  • @RonMaupin Absolutely - if Gbit inter-VLAN routing is required and 100 Mbit/s or so VPN is fine, using an L3 switch and the 4000 as separate WAN/VPN router would be reasonable. – Zac67 Oct 19 '20 at 20:43

The ISR 4000 series routers come with a platform shaper that will limit total throughput through the L3 forwarding feature.

In the case of the 4331, these figures are:

  • Default: 100Mbps
  • FL-4330-PERF-K9: 300Mbps
  • FL-4330-BOOST-K9: as fast as the router's CPU cores can deliver.

Having the Boost license unlocks line rate for the given 1Gbit/s sec interfaces. Hovewer, this comes at a price.

With default and PERF licensing, Cisco promises that the router can deliver up to the platform shaper's limit, no matter what combination of features you throw at it (IPSec, NAT, Hierachrical QoS, WaaS, Firewalling ...).

With the boost license, all CPU cores can be unlocked, and when running advanced combinations of features, you might hit the router's limits before line rate is achieved on the given interfaces.

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

Educated guess: When equipped with a switching module, L2-forwarding within that switch module is probably not subject to the platform shaper's limitations. Inter-VLAN forwarding, even when using ports of the same switching module, is probably subject to the platform shaper.


Seems I was not quite right. Inter module forwarding seems not to be subject to platform throughput licensing.

See Section "Multigigabit Fabric" in https://www.cisco.com/c/en/us/products/collateral/routers/4000-series-integrated-services-routers-isr/data_sheet_c78-612808.html

Throughput for direct module-to-module traffic using the MGF will thereby not be limited by the platform’s performance license levels. Layer 2 switching of packets is thus done at the full Gigabit Ethernet line rate, either local to each LAN switch NIM or when transferring the MGF with multiple MGF-enabled modules installed in the system; module-to-module MGF traffic throughput is limited to 1 Gbps.

However even that document still does not say if L3 forwarded traffic from SVI to SVI is leaving the MGF and hits the CPUs, where it's probably subject to throughput licensing.

  • Does that mean that within a switching module (we do have one) the performance licenses are not needed? – Fang Oct 19 '20 at 19:58
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    See my edit. L2 switched traffic is not subject to throughput licensing. L3 forwarded traffic from SVI to SVI might still be. Safe option (if affordable): get the boost license. – Marc 'netztier' Luethi Oct 19 '20 at 20:08
  • If you manage to get 1Gbit/s line rate inter vlan forwarding on a switch module (while keeping the PERF license), please be sure to report back. I'm also interested to know. – Marc 'netztier' Luethi Oct 19 '20 at 20:18
  • We didn't manage to get it working and then bought an additional dedicated switch. – Fang Oct 29 '20 at 17:04

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