On 2007/04/20 09:48, Toni Mueller wrote: > Hi Claudio, > > On Fri, 06.04.2007 at 12:09:38 +0200, Claudio Jeker <[EMAIL PROTECTED]> wrote: > > Even the most expensive Cisco/Foundry/Extreme switches have not the CPU > > power to route or filter packets. > > how comes they boast running BGP and such stuff? Eg. Cisco 6509 and up,
Smaller Ciscos than that run BGP (e.g. cat3550/3560/3750) at least up to some routing table sizes (no chance for a full internet table, but some people run these in a mixed network with OpenBGP handling most of the BGP work via multihop sessions, and the L3 switches handling much of the packet forwarding). > or Extreme Black Diamond? This requires real routing capabilities, > doesn't it? They have a small/medium sized cpu, which runs the routing protocols and maintaining the FDB, there are also fast lookup tables (called TCAM on Cisco) which can be used by the switch ASICs to lookup IP destinations and switch them. Check out the 'local context addressing' section in http://www.juniper.net/solutions/literature/white_papers/200161.pdf (when reading this article bear in mind Cisco now sell a lot of L3 switches for what is traditionally 'router' use, obviously Juniper would like to discourage that :-) Run out of TCAM space (as might happen with worm/ddos traffic), or configure things that need the main processor to look at packets, and the CPU (e.g. PowerPC 405, MIPS R7000) starts to get awfully busy...
