Layer 2 Switching protocols (IPv4, IPv6, TCP, UDP, STP, ECMP, 802.1d, 802.1s, 802.1w, 802.1x)
Layer 3 Routing protocols (OSPF, BGP, VRFs)
Stateful firewalls
Programming or scripting
VPNs
Wireless technologies (802.1a/b/g/n)
Global and Local Server Load-Balancing
Multicast (PIM-SM, MSDP, IGMP)