My routers are connected each other through Hub with FastEthernet cables. When I looked into cdp packet captured by Ethereal software, I found CDP packet looks like this:
IEEE 802.3 Ethernet //layer2 Logical-Link Control //layer3 Cisco Discovery Protocol //layer4
Why CDP protocol is called as layer 2 ? Also if I get CDP packet over serial cable(PPP?), is CDP still layer 2 ? I think PPP protocol is layer 2.
I'm so confused. Help me out..