On Thu, Oct 25, 2007 at 05:36:11PM -0400, Scott Brim wrote:
On 25 Oct 2007 at 17:02 -0400, Jason Frisvold allegedly wrote:
Anyone have any experience with these Anagran flow routers? Are they that much of a departure from traditional routing that it makes a big difference?
There's no difference in routing per se. Rather it's in-band signaling of QoS parameters to provide feedback to queue management.
I read over the vendor's site when that article was sent, and I'll be honest, a lot of what they are trumpeting are steps backwards in router performance. While the site is pretty light on the details, Anagram's "Fast Flow Routing Architecture" sounds very similar to dated multilayer switching approaches. CEF-like adjacency certainly provides higher routing throughput with less overhead. So if it's a win, it must be a win because the cost of going back to a flow-caching is offset by a gain in better QoS. Their QoS details are a bit sketchy, but this would worry me: BTC basically '"watches" every flow. By constantly comparing each flow's behavior over time against a simple set of operator-defined rules per flow class, BTC can identify "suspect" flows that by virtue of their duration, byte count, source/destination, or other criteria, require some form of corrective or policing action. So now there's a "flow table" that in the forwarding plane. What happens when the flow table overflows? How does the router decide when to age-out a flow? I have yet to see a flow-centric filtering device save the network when it's flow/session table is what's under attack. -- Ross Vandegrift ross@kallisti.us "The good Christian should beware of mathematicians, and all those who make empty prophecies. The danger already exists that the mathematicians have made a covenant with the devil to darken the spirit and to confine man in the bonds of Hell." --St. Augustine, De Genesi ad Litteram, Book II, xviii, 37