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What are the different VLAN frame tagging techniques?
Two trunking protocols are usually used today for frame tagging: Inter-Switch Link (ISL) – Cisco’s proprietary VLAN tagging protocol. IEEE 802.1q – IEEE’s VLAN tagging protocol. Since it is an open standard, it can be used for tagging between switches from different vendors.
What does untagged VLAN mean?
Untagged VLANs An untagged port, or access port on a Cisco switch, connects to hosts (such as a server). The host is unaware of any VLAN configuration. The connected host sends its traffic without any VLAN tag on the frames. When the frame reaches the switch port, the switch will add the VLAN tag.
What is the difference between untagged and tagged port?
Untagged packet received on an untagged port: forward based on VLAN configured on the port. Tagged packet received on an untagged port: drop packet except the tag is the same as the VLAN configured on the port. Tagged packet received on a tagged port: forward based on the VLAN tag in the packet.
What is VLAN tagging and untagging?
The meaning of “tagged” and “untagged” is this: If a VLAN is tagged on a port, it means that data from that VLAN is sent out the port in 802.1q format, which has a VID (a tag) that identifies what VLAN it’s associated with. Also, data received with a VLAN tag is placed in the appropriate VLAN.
What is a “tagged” port in VLAN context?
Tagged ports are going to be the trunk ports (the port, that carries multiple VLANs) and usually this port is connected to a router or another switch/bridge, you can have multiple trunk ports as well. Tagged ports are always carrying packets with a VLAN tag (hence the name) and you must ALWAYS specify the tagged ports for each VLAN ID you want this port to forward. It is possible that a port is a tagged port for one VLAN ID and the same port is an untagged port for a different VLAN ID, but
Why do we use VLAN tagged port?
By now, you can probably guess where this answer is heading. The use of a tagged port (aka trunk port for some vendors) is to allow you to send the data from more than one VLAN over a single link . The tagging allows the receiving device to understand which traffic belongs to which VLAN allowing it to maintain the logical separation.