NetworkingConcepts

VTP (VLAN Trunking Protocol) A Cisco proprietary protocol used to manage VLANs across switches. Allows centralized creation, deletion, and renaming of VLANs. Advertises VLAN information to other switches in the same VTP domain.  How It Works VTP advertisements are sent over trunk links. Switches exchange VLAN information such as VLAN IDs and names. One switch can act as a "server" to create, modify, or delete VLANs, and others learn automatically. Key Terms & Modes VTP Domain: Logical group of switches sharing VLAN info. VTP Modes: Server: Default mode; can create/modify VLANs and advertise them. Client: Cannot create/modify VLANs; receives VLAN info from server. Transparent: Forwards VTP updates but does not apply them Off (VTPv3): Switch does not participate in VTP. VTP Revision Number: Version number that increases with VLAN database changes VTP Pruning: Feature that prevents unnecessary VLAN traffic from being sent o...

Layer-2 Concepts VLAN VTP STP PVST Layer-3 Concepts

  VLAN (Virtual Local Area Network) Logical segmentation of a switch into multiple broadcast domains. Increases security, reduces broadcast traffic, and improves management. Each VLAN acts as a separate Layer 2 network (requires a router or Layer 3 switch for inter-VLAN communication). Access Port Belongs to a single VLAN . Carries untagged traffic . Used to connect end devices (PCs, printers, IP phones). Trunk Port Can carry multiple VLANs simultaneously. Frames are tagged with 802.1Q headers to identify VLANs. Commonly used between switches, or switch-to-router/switch-to-server links. Native VLAN On an 802.1Q trunk, the VLAN whose traffic is sent untagged . Default is VLAN 1 (but best practice: change it). Must be the same on both ends of a trunk to avoid VLAN mismatch issues . Quick Interview One-Liners: VLAN = logical segmentation. Access port = single VLAN, untagged. Trunk port = multiple VLANs, tagged. Native VLA...

  Definition of STP Spanning Tree Protocol (STP) is a Layer 2 protocol that prevents switching loops in a network by dynamically blocking redundant paths and creating a loop-free logical topology. Key Terms in STP Bridge ID (BID): Unique identifier for each switch, made of Bridge Priority (default 32768) + MAC address . Root Bridge: The switch with the lowest Bridge ID ; becomes the logical center of the STP topology. Root Port (RP): On non-root switches, the port with the lowest path cost to reach the Root Bridge. Only one Root Port per switch. Designated Port (DP): On each network segment, the port that has the lowest cost to the Root Bridge . Note: All ports in root bridge is designated port.   Blocked/Non-Designated Port: Ports that are neither Root nor Designated . These remain in a blocking state to prevent loops. Path Cost: A numeric value assigned to a network link based on its bandwidth. Lower cost = higher bandwidth (preferred path). Used by ST...