[c-nsp] 3845 maxing out at 400 Mbps

[Tony Varriale]

On 3/28/2011 9:14 PM, Frank Bulk wrote:
> We have two 3845's as border routers, each with three GigE interfaces (one
> facing upstream, the other downstream, the third facing the other 3845).
> The first 3845 has a typical packet-size mix (residential/business Internet)
> is consistently maxing out at 400 Mbps (predominately ingress because of
> asymmetric routing) running at about 43 kpps and 40% CPU.  It's flat-lines
> very evenly, uncannily so.  We checked and double-checked transport and it's
> set much higher, the same as the second 3845.
>
> The second 3845, which has a mix of both ingress and egress traffic at a
> combined 82 kpps (35 kpps ingress/50 kpps egress) but lower combined 360
> Mbps operates at a higher CPU (presumably because there's also egress
> traffic) with no flatlining.
>
> The ACLs are BCP 38-oriented with eBGP; no rate-limiting.  We're running
> 124-11.XW2.
>
> Any ideas?  The numbers are well below Cisco's router spec sheet.
>
> Frank
The first idea is pretty obvious: different packet sizes.  Why so?  The 
second idea would be to make sure you are staying in the CEF path as 
much as possible.  Verify that yet?

tv