Hi
This is one of the wierdest threads I have seen.
First of all I think that it will be worth reading at least the first three or four chapters of the classic book "TCP IP Illiustrated" TCP/IP Illustrated, Vol. 1: The Protocols (Addison-Wesley Professional Computing Series): W. Richard... so that at the basic terms and concepts are understood.
A few pointers :
1. Ethernet works with MAC addresses and not IP adresses. There is no such thing as an IP address for Ethernet (and Ethernet protocol)
2. Networking doesn't need IP, although nowadays most traffic is based on IP and so IP addreses are required. In fact it is possible to communicate between HW and PCs without IP addresses - one example is just using an Ethernet protocol as is done by uNetwork: http://www.utasker.com/docs/uTasker/uNetwork.PDF which is incorporated in the uTasker stack and allows distributed processing in local networks (that is, a software runs on multiple processors/nodes as a single OS without the tasks involved needing to know on which physical nodes other OS tasks in the networked software are actually running on. It is possible to also communicate with PCs like this, although not using the typical IP ports which the vast majority of applications make use of.
3. Ethernet may also use multiple MAC addresses (some EMACs include multiple unicast MAC address support, which helps in such situations). Multicast MAC addresses are also often used in addition (typically together with IP though).
4. A network node based on IP will need an IP address. In the simpest case an IPv4 address. However often there wil be multiple IP addresses - a node can have multiple IP unicast IPv4 and/or IPv6 addresses if it wants (not to mention multicast group addresses). IPv6 will tend to have multiple IPv6 addresses - at least a link-local address and usually a global address too.
Since WANs still often don't support native IPv6 some sort of tunneling is often in operation which may be carrying IPv6 inside IPv4: http://www.utasker.com/docs/uTasker/uTaskerIPV6.PDF
So essentially no IP is needed for communication but for standard practial networking it makes sense to have also an IP network stack that will just allow everything to work for you when needed. Stacks vary in the number of protocols, features, versions of protocols etc. they support (there are thousands which are possible and some which are essential). Before making decisions on embedded networking on does need to know what one wants to be able to do....
Regards
Mark
Kinetis: µTasker Kinetis support
K60: µTasker Kinetis TWR-K60N512 support / µTasker Kinetis TWR-K60D100M support / µTasker Kinetis TWR-K60F120M support
IPv6: http://www.utasker.com/docs/uTasker/uTaskerIPV6.PDF
Multi-homed networking: http://www.utasker.com/docs/uTasker/uTaskerNetworking.pdf
Distributed System Networking: http://www.utasker.com/docs/uTasker/uNetwork.PDF
For the complete "out-of-the-box" Kinetis experience and faster time to market