Part 1: Core Concepts (2 Marks)
- Enterprise Network Architecture: The structured interconnection of compute servers, workstations, storage devices, and communication peripherals across campuses to facilitate business data exchange.
- L2 vs L3 Switches: Layer 2 switches forward traffic based strictly on hardware MAC addresses within a broadcast domain; Layer 3 switches perform hardware wire-speed IP routing across VLANs using ASICs.
- Next-Generation Firewall (NGFW): Hardware gateway that combines deep packet inspection (DPI), intrusion prevention (IPS), application awareness, and TLS decryption.
Part 2: Structural Frameworks (10 Marks)
Enterprise Hardware Topology & Redundancy
- Internet Gateway / Dual ISP Feeds
- Border NGFW Cluster (HA Pair)
- Core Switches (VRRP / HSRP)
- / \
- [Distribution Switch A] [Distribution Switch B]
- / \ / \
- [Access 1] [Access 2] [Access 3] [Access 4]
Part 3: Distinction Tables
| Basis of Comparison | Layer 2 Switch | Router |
|---|---|---|
| PDU Handled | Data Link Frames. | Network IP Packets. |
| Addressing | 48-bit MAC addresses. | 32-bit (IPv4) or 128-bit (IPv6) addresses. |
| Broadcast Domain | Breaks collision domains; maintains single broadcast domain. | Breaks broadcast domains; blocks broadcasts by default. |
Part 4: Worked Problems & Exam Traps
Spanning Tree Protocol (STP - IEEE 802.1D) Root Bridge Election
- Bridge Priority: Lowest Bridge ID (Priority + MAC) becomes Root Bridge. Default priority: 32,768.
- Root Ports: Each non-root switch selects port with lowest path cost to Root Bridge.
- Designated Ports: Port on each segment with lowest cost to Root Bridge.
- Blocking Ports: All other ports placed in Alternate/Blocking state to eliminate Layer 2 loops.
Layer 2 loops cause fatal Broadcast Storms and MAC address table instability within milliseconds, crashing switch backplanes.