I work with a lot of single-site small and medium-sized businesses (10-100 users) that just need a single router to connect their LAN to the Internet... so it needs to do NAT, IOS Firewall (ip inspect), and various incoming PAT port forwardings. Streaming media is popular so it's likely the WAN connection won't be as bursty as you might think.
I know it's really hard to generalize but as a first approximation, I've been recommending the Cisco 87x series when the ISP provides a connection up to 2Mbps, a Cisco 18xx when the ISP WAN connection is 2Mbps-5Mbps, and finally a Cisco 28xx when the ISP WAN connection guaranteed service speed is between 5Mbps and 10Mbps
(I also recommend the ASA 55xx series, but this note is just wanting to know about IOS ROUTER performance, not PIX/ASA)
My question: I realize that each customer is different and all factors (like VPNs, big access-lists, etc) have to be considered, but is my "first guess" of a 87x, 18xx, or 28xx router model based completely on the ISP WAN speed reasonable or am I completely off base?
In my googling, I've seen various tables of SWITCHING performance of various routers, but can those pps numbers be applied to ROUTING performance as well?
(I'm guessing routing/nat/firewall is more CPU intensive that just port-to-port switching..)
Thanks for any opinions...
The switching performance often would be routing in the sense that a complete route table lookup isn't performed for the packet, instead the packet is L3 "switched". I.e. the maximum performance that should be obtainable with something like a file copy. However, as the document also notes, actual performance could be much less. (Much depends on the configuration. Something like NAT/PAT could have a big impact.) Also, when doing an actual file copy using TCP, don't forget the router also has to process the return ACK flow.