Cisco Interrupt Level Switching

Question:

I needed some information on Catalyst 3560V2 Price Interrupt level switching. We have recently had a case in our organization where the WAN bandwidth on a Cisco 2801 router was upgraded and which probably overwhelmed the bandwidth that the router could suport (46 Mbps). Post the upgraded the CPU process of the router would go high upto 90% during production hours. There was no process on the router which showed up using the high resources and it was apprently the interrupt switching that was driving the utilization high. We had CEF enabled on all interfaces on the router as well.

1) I want to know what exactly interrupt level switching is ?

2) Why is the packet interrupt swicthed when there is CEF enabled?

3) Cisco documents say that "Interrupt-level switching means that when a packet arrives, an interrupt is triggered which causes the CPU to postpone other     tasks in order to handle that packet.At times when there is heavy traffic load will this not hamper other processes ?

Answer:

please review these docs for more info.

http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_tech_note09186a00800a7306.Catalyst 3560V2 shtml

http://www.cisco.com/en/US/products/hw/routers/ps359/products_tech_note09186a00801c2af0.shtml