encapsulation dot1q 3

Encapsulation with Dot1Q (802.1Q) is a network protocol mechanism that provides VLAN tagging to Ethernet frames. VLANs (Virtual Local Area Networks) are used for traffic isolation and management in switched networks. Here's an explanation:

1. **Dot1Q Tagging**: It adds a 4-byte tag to the Ethernet header, specifically after the MAC address but before the LLC/SNAP or IP segments. This tag contains two fields - VLAN Identifier (VID) and Priority/Cos (Priority Code Point), which allows you to identify and prioritize different types of traffic.

2. **VLAN Encapsulation**: By tagging packets, it isolates the traffic belonging to each VLAN from others on the same physical link. This helps to prevent broadcast storms and unauthorized access between VLANs. Each switch port can be configured to either trunk (forward all tagged traffic) or access (only forward untagged traffic).

3. **Benefits**: Dot1Q encapsulation enables efficient use of bandwidth, enhances security by separating sensitive data, and simplifies network administration since each VLAN acts as a logical subnet.