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
