This chapter is from the book
- VLAN provides logical grouping of the hosts to restrict the broadcast domain.
- VLANs are usually categorized into local and end-to-end VLANs, and each has its own pros and cons.
- With the help of trunking, VLANS can be easily extended over a single physical link.
- ISL and 802.1Q are two trunking protocols, with dot1Q the industry standard.
- Dot1Q frames insert 4 bytes and recalculate the CRC.
- Native VLAN is not encapsulated in dot1Q trunking, and it is important to have same native VLAN on both sides of the switches.
- VTP is used to distribute VLAN databases. It has multiple versions and modes. VTP works in server, client, and transparent mode.
- Any switch with a higher revision number can overwrite the VLAN database. Insert the new switch with caution and follow the recommended steps.
- EtherChannel is a technology that was originally developed by Cisco as a LAN switch-to-switch technique of grouping several Fast or Gigabit Ethernet ports into one logical channel.
- PagP and LACP are the two main protocols for EtherChannel.
- For EtherChannel, it is highly recommended to use the even number of ports in the channel to have better load balancing.