What is QinQ in networking?

A Q-in-Q VLAN tunnel enables a service provider to segregate the traffic of different customers in their infrastructure, while still giving the customer a full range of VLANs for their internal use by adding a second 802.1Q tag to an already tagged frame.

What is selective QinQ?

Selective Q-in-Q is the way to achieve Q-in-Q per CVLAN basis, where you have the flexibility to selectively choose and add service VLAN tag based on the customer VLAN.

What is Svlan and Cvlan?

CVLAN tag—Identifies the VLAN to which the frame belongs when it is transmitted in the customer network. SVLAN tag—Identifies the VLAN to which the QinQ frame belongs when it is transmitted in the service provider network. The service provider allocates the SVLAN tag to the customer.

What is the TPID value of an 802.1Q tagged frame?

0x8100
Two bytes are used for the tag protocol identifier (TPID), the other two bytes for tag control information (TCI). The TCI field is further divided into PCP, DEI, and VID. A 16-bit field set to a value of 0x8100 in order to identify the frame as an IEEE 802.1Q-tagged frame.

What is 802.1Q tunneling?

802.1Q tunneling enables Service Providers to use a single VLAN to support customers who have multiple VLANs, while preserving customer VLAN IDs and keeping traffic in different customer VLANs segregated. A port configured to support 802.1Q tunneling is called a tunnel port.

What is inner VLAN and outer VLAN?

Within an Ethernet Frame, these two tags are often known as “Inner tag” and “Outer tag”. “Inner tags” contain VLAN information that belong to the traffic of the NSP’s customers. The “Outer tags” contains information relating to the NSP’s VLAN networks.

What is the difference between tagged and untagged VLAN?

VLAN-enabled ports are generally categorized in one of two ways, tagged or untagged. These may also be referred to as “trunk” or “access” respectively. The purpose of a tagged or “trunked” port is to pass traffic for multiple VLAN’s, whereas an untagged or “access” port accepts traffic for only a single VLAN.

What is VLAN stacking?

The VLAN Stacking allows the telecom operator to place all traffic from a single customer (which could be multiple VLAN’s) into a single VLAN simplifying management across his network.

What is the purpose of 802.1Q tagging?

The 802.1Q tagging protocol allows the Ethernet frame size to increase by four bytes to a range of 68 to 1522 bytes. This size increase is due to the insertion of a four-byte VLAN tag into the frame. The tags, which include a VLAN Identifier (VID), are attached to each Ethernet frame by MAC address.

How large is the VLAN ID in the 802.1Q tag?

4-byte
IEEE 802.1Q adds a 4-byte VLAN tag between the Source/Destination MAC address and Length/Type fields of an Ethernet frame to identify the VLAN to which the frame belongs.

What is the difference between 802.1Q and 802.1 ad?

IEEE 802.1Q defines a 12-bit VLAN ID field and can identify only 4096 VLANs. With the growth of networks, this limitation has become more acute. IEEE 802.1ad, as an amendment to IEEE 802.1Q, adds an additional 802.1Q tag (also known as a VLAN tag) to single-tagged 802.1Q packets, expanding VLAN space to 4094 x 4094.