Why is routing neither CPU nor memory intensive? [closed]

Solution 1:

What part of a router's job takes up RAM? Precious little. Packets in, packets out. The network stacks of modern operating systems are very well-tuned, and all packet inspection and routing happen directly in the kernel, so no ancillary user-land code is necessary.

If your router is also performing NAT, then the state table would consume some memory, but even a modest 2GB system is able to store hundreds of thousands of NAT state table entries without blinking an eye.

Additionally, if your router is performing dynamic routing duties (VRRP, BGP, etc.) those will consume memory.

To conclude, though, most firewall and routing tasks are very easy on system resources.