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IEEE 802.1Q, often referred to as Dot1q, is the networking standard that supports virtual local area networking (VLANs) on an IEEE 802.3 Ethernet network. The standard defines a system of VLAN tagging for Ethernet frames and the accompanying procedures to be used by bridges and switches in handling such frames.
With ISL, an Ethernet frame is encapsulated with a header that transports VLAN IDs between switches and routers. With IEEE 802.1Q the tag is internal. This is a key advantage for IEEE 802.1Q as it means tagged frames can be sent over standard Ethernet links. ISL does add overhead to the frame as a 26-byte header containing a 10-bit VLAN ID.
VLANs operate at the data link layer of the OSI model. Administrators often configure a VLAN to map directly to an IP network, or subnet, which gives the appearance of involving the network layer. Generally, VLANs within the same organization will be assigned different non-overlapping network address ranges. This is not a requirement of VLANs.
The newly inserted VLAN header's EtherType is set to 0x8100 to identify the following data as a VLAN tag. 12 bits are used for the VLAN ID, the other bits in the VLAN fields are filled in according to the QoS policy, etc. of the interface at which the tag imposition occurred.
Without using MVRP, either a manual configuration of VLAN trunks or use of a manufacturer's proprietary method is necessary. It is through MVRP that dynamic VLAN entries will be updated in the filtering database. In short, MVRP helps to maintain VLAN configuration dynamically based on current network configurations. 802.1Q allows for:
That value was chosen because the maximum length of the data field of an Ethernet 802.3 frame is 1500 bytes and 1536 is equivalent to the number 600 in the hexadecimal numeral system. Thus, values of 1500 and below for this field indicate that the field is used as the size of the payload of the Ethernet frame while values of 1536 and above ...
One or more logical or physical interfaces may have a VRF and these VRFs do not share routes. Therefore, the packets are only forwarded between interfaces on the same VRF. VRFs are the TCP/IP layer 3 equivalent of a VLAN. Because the routing instances are independent, the same or overlapping IP addresses can be used without conflicting with ...
Multiple VLAN Registration Protocol (for provider bridges) IEEE 802.1ad: 01-80-C2-00-00-0E: Local LAN Link, never crosses another device 0x88CC Link Layer Discovery Protocol (primary) 0x88F7 Precision Time Protocol (PTP) version 2 over Ethernet (802.1AS) 01-80-C2-00-00-21: 0x88F5 GARP VLAN Registration Protocol (also known as IEEE 802.1Q GVRP)