4400 throughput

[asmlicense]

Dears,

We have the throghput problems on 4331 and 4431 and we decided just to buy and activate performance licenses.

On 4331 we have already install Performance License which increase from 100 mbps to 300 mbps. The next and the last license type is Boost License which as I know will give Over 2 Gbps. But there is Aggregate CEF Only Throughput in description and actualy I didn't understand what does it mean. Could someone explan Aggregate CEF Only Throughput section.

[Kasun Bandara]

hope this helps

https://community.cisco.com/t5/routing/cisco-4k-router/td-p/4060489

[asmlicense]

Hi Kasun,

As I understood from the topic Boot license just divide 2 Gbps between 3 ports (Gi0/0/0, Gi0/0/1, Gi0/0/2). Right?

[Joseph W. Doherty]

Yes and no.

An ISR use a CPU for much of its traffic forwarding.  More-or-less, that CPU doesn't really much care about number of interfaces, beyond more interfaces, of the same bandwidth capability, can provide more traffic to forward.

For example, ten gig interface running at about 10% utilization, each, to the CPU, is, more-or-less, the same as one gig interface running at 100%; i.e. both are providing a gig's worth of traffic to forward.

CPU capacity, is spread across all transit traffic.

BTW, with three gig interfaces, the router might have up to three (not six) gig of traffic to forward.

Also BTW, a Boost license doesn't guarantee the data sheet's noted bandwidth capability.  Actual bandwidth capacity can be (much), much less (throughput, with Boost license, dependent on "nature" of traffic and your router's config).

[Joseph W. Doherty]

It's a fancy way of saying in the best possible case.

Base license and performance licenses, more-or-less, guarantee their bandwidth throughput.  Not so with boost license.

Boost license, basically, allows the 4k to operate like earlier ISRs (with very variable performance).

[MHM Cisco World]

[Joseph W. Doherty]

Unfortunately, at least to me, that (Cisco?) slide, still seems to confuse the issue.

On a switch or router, forwarding is done once, i.e. in => out.

The aggregate (sum of all interfaces) bandwidth consumption entering, normally (assuming traffic not being dropped), is the same aggregate (sum of all interfaces) bandwidth consumption exiting.

Consider a router or switch with just two gig ports, running in full duplex mode.

A maximum of 2 Gbps can enter the device, as well as a maximum 2 Gbps can exit the device.  As, again, in => out, maximum bandwidth that could be forwarded is 2 Gbps.  However, Cisco will say 4 Gbps is crossing the fabric or backplane even though, if you remove the router and switch, and directly connect the two gig links, i.e. making a single (duplex) gig link, they will then say you're now transporting 2 Gbps.  I.e. or, conversely, you insert a router or switch into a gig link, and the bandwidth crossing the device's innards just doubled!

So, yes indeed, vendors often do like to "inflate" performance numbers for what's actually happening.  It's not really false, you just need to understand exactly what the numbers represent.