[f-nsp] Looking for throughput infos

[Kristian Larsson]

On Thu, Sep 14, 2006 at 07:21:07PM +0200, Stefan Neufeind wrote:
> Gerald Krause wrote:
> > On Thursday 14 September 2006 17:56, Jens Brey wrote:
> >> Hi,
> >>
> >> does someone has informations or a link about the throughput of a
> >> BigIron 4000 with M4 Modules, 512 MB RAM, Gigabit Uplink and 3 BGP Full
> >> Tables?
> >>
> >> I heard from something around 850 MBit. Is this right?
> >> Average packetsize is around 500 Byte.
> > 
> > IMHO the main limiting factor for the max throughput of a B4000 is the number 
> > of new flows/second because of the small cam size and not the packetsize 
> > itself. If you have 500 byte packets from/to only some certain 
> > sources/destinations I wouldn't be surprised if the B4000 could move 1GBit/s 
> > or more. The pain begins definitively when the flows grow up but this is 
> > something you hardly can control in an internet environment.
> 
> Hi,
> 
> but even then you can try to optimize a bit with net-aggregate, if you
> haven't yet already done so, try to increase cam-size etc.
> To my understanding everything that can be "switched" (routed) with
> information from CAM is quite fast and I *think* that 1GBit or more
> should be possible. But this is not based on practical experience with
> that small packets you have.
Just as mentioned, when the forwarding information
is in CAM the BI4k is wicked fast, 1Gbps is no
match. Just pure packet forwarding, it can do
wirespeed.

But since the CAM is route-cache based you need to
insert new entries from time to time, this is not
to bad. What is bad is when your trying to forward
packets to more destinations than can fit in your
CAM, then the CPU becomes busy with filling the
CAM with new entries and getting rid of the oldest
one. Since all entries really needs to be in CAM,
the CPU inserts and removes entries all the time,
this is called CAM trashing. Depending on how many
flows it needs to insert/remove per second you
throughput will drop drastically. 

We have used and still use BI4ks for routing 'on
the Internet' and it's working. From time to time,
the CAM is programmed with a faulty entry. Some
packets are misrouted and so forth.
Foundrys are fast, but it's not all about speed,
you need to move packets in the right direction as
well.

Tell us more of your environment and we can
hopefully give better answers :)

Regards,
   Kristian.

-- 
Kristian Larsson                                   KLL-RIPE
Network Engineer                      Net at Once [AS35706]
+46 704 910401			     kristian at spritelink.se