Study Focus Areas
- OSI Model & TCP/IP Stack
- Subnetting & IPv4/IPv6
- VLANs, Trunking (802.1Q), and Inter-VLAN Routing
- Routing Protocols: RIP, OSPF, EIGRP
- ACLs, NAT, and QoS
- Wireless, Automation, and Security Fundamentals
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SDN Architecture
Architecture Layers (Conceptual Stack)
- Application Layer: Where intent and policy are defined (e.g., security rules, traffic priorities).
- Control Layer: Where decisions are made based on that intent (e.g., SDN controllers like APIC).
- Infrastructure Layer: Where packets are actually forwarded—your physical switches and routers.
Design Components (Network Implementation)
- Underlay: The physical network (switches, routers, IP links).
- Overlay: The virtual network (VXLAN, GRE tunnels) running on top of the underlay.
- Fabric: The automated system that coordinates overlay and underlay, enforcing control and policy.
PoE Standards
- 802.3af – VoIP, Wireless APs
- 802.3at (PoE+) – Dual-Band APs, IP Phones
- 802.3bt (PoE++) – PTZ Cameras, Thin Clients
Router on a Stick
Use a single physical router interface with 802.1Q trunk to route between VLANs using subinterfaces.
ACL Types
- Standard ACL – Filters by source IP. 1–99 / 1300–1999
- Extended ACL – Filters by source/destination/protocol/port. 100–199 / 2000–2699
Redundancy Protocols
- HSRP – Cisco proprietary, uses active/standby
- VRRP – Open standard, elects master
- GLBP – Cisco proprietary, supports load balancing