Why we say router works as software while swithch as hardware?

johnifanx98

I heard about switch's logic is implemented in ASIC, while router's in firmware. Any reason the router does not use ASIC? Routing table should not be the reason, since switch also has arp table. Then could it because the router uses multiple routing protocols? Such protocol are too complex to be implemented in ASIC?

TehToG

I think you misunderstand what an ASIC is and why it's so good. An ASIC is a logical processor. It only does ONE task. Unlike a modern processor which can be fed data and instructions to perform on that data, an ASIC gets data in, does a set task on it, outputs it.

The advantage of an ASIC is that it's very fast, perfect for layer 2 switching. The downside is that it's not flexible on the instructions AT ALL. Routing is just too dynamic a process to be completed with an ASIC implementation. Now there may be very high end routers which use ASICs (and i'd suggest cisco routers use ASICS for some tasks.)

TL;dr - ASICs (as the name says) are for application specific tasks.