okay .. lets get the expert view points on this ... from
http://www.networkworld.com/reviews/2003/0714rev.html "We measured the performance effect of filtering with three metrics: throughput, average latency and maximum latency (see How we did it). To determine routers' ability to recover from failure, we also measured reboot times under load for each device. " humm what was asked earlier wasn't it....
" In the filtering cases, we asked vendors to configure one router with filters covering multiple conditions: source and destination IP address; protocol number; and TCP or User Datagram Protocol (UDP) port number. We asked vendors to set their last filter as the one we'd use for test traffic, forcing the routers to cycle through their entire filter list. Vendors also enabled logging, so we'd know how many packets "hit" each filter. Tests were run with eight, 16, 64 and 256 unique filters applied.
In the routing test cases, we asked vendors not only to apply various numbers of filters but also to enable two routing protocols - Border Gateway Protocol (BGP) and Open Shortest Path First (OSPF).
We ran through the various numbers of filters with two routing scenarios, dubbed "small tables" and "big tables." In the small-table case, we advertised reachability information for 64 networks each over BGP and OSPF. That's the sort of table size a small or midsize business might run.
In the big-table case, we advertised 125,000 routes using BGP and 4,096 using OSPF. The first number represents the current size of the Internet "full table" - the total number of networks visible in the global Internet. The second number represents about 10% of the size of a Tier-1 ISP's OSPF Area 0 network - the core of any OSPF network.
Holding the full Internet table might seem like a lot to ask of an access router. However, a growing number of corporations use multi-homed connections - BGP connections to different ISPs for redundancy - and their actual table size might be at least twice as large as the one we used. "
Well you can read the rest.....