| Security |
| Switching VLAN STP Port |
10. VLAN Continued
- Inter-VLAN communication is only possible via a router or Layer 3 switch
- Each VLAN has a unique ID (between 1–4094)
- Switch ports can be manually assigned to specific VLANs (Access Ports)
- Ports that carry traffic from multiple VLANs are called Trunk ports and use tagging protocols like IEEE 802.1Q
11. Port Security Features
Port Security
Restricts the number of allowed MAC addresses per port
Switch(config-if)#switchport port-security
Switch(config-if)#switchport port-security maximum 2
Switch(config-if)#switchport port-security violation shutdown
Switch(config-if)#switchport port-security mac-address 0000.1111.2222
DHCP Snooping
- Blocks rogue DHCP servers
- Designates trusted ports for legitimate DHCP responses
ARP Inspection
- Prevents spoofing and ARP poisoning attacks
- Uses DHCP Snooping tables for verification
Flood Guard
- Protects the switch from broadcast storms and MAC flooding
- Helps prevent denial-of-service (DoS) attacks
BPDU Guard & Root Guard
- BPDU Guard: Prevents BPDU frames on access ports
- Root Guard: Prevents undesired switches from becoming Root Bridge
12. Advanced Switching Features
Port Bonding (Link Aggregation)
- Combines multiple physical links into a single logical link
- Follows the IEEE 802.3ad standard
- Boosts bandwidth and redundancy
Power over Ethernet (PoE)
- Delivers electrical power through Ethernet cables
- Supports IP cameras, VoIP phones, and other powered devices
- Complies with IEEE 802.3af and IEEE 802.3at standards
Port Mirroring / SPAN
- Copies traffic from one or more ports to a monitoring port
- Used for network analysis and intrusion detection
Switch(config)#monitor session 1 source interface Fa0/1
Switch(config)#monitor session 1 destination interface Fa0/10
13. Conclusion
Layer 2 switching combined with VLANs and advanced security features forms the backbone of modern network architecture. A solid understanding of STP, RSTP, and security protocols such as Port Security and DHCP Snooping is essential for building flexible, scalable, and secure networks. Mastering these concepts is a powerful advantage for both the Network+ exam and professional implementation.
