Trunking or VLAN Tagging
- Switch ports can be allocated to individual VLANs.
- Subsequently, Broadcasts are limited to their own VLAN.
- Different VLANs must be connected via routers or routing modules (layer 3 devices).
- Trunking/VLAN header is added to frame by switch on the outbound side to guide frame to appropriate VLAN within recipient switch.
- Cisco adds 26 bytes of ISL VLAN header for trunking on the front-end and 4 bytes of their own CRC on the back-end of the frame.
- IEEE adds 4 bytes for 802.1q header on trunk.
- Minimum Ethernet frame size = 64 bytes.
- Maximum Ethernet frame size = 1518 bytes.
- Max Enet size = 1522 or 1544 bytes with trunking.
- Use "protocol" instead of "packet" when building Data Pattern matches within or after the network layer header