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What is tunnel VLAN?
Understanding 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 a dot1q tunnel?
802.1Q tunneling (aka Q-in-Q) is a technique often used by Metro Ethernet providers as a layer 2 VPN for customers. By using a different VLAN tag for each customer we can separate the traffic from different customers and also transparently transfer it throughout the service provider network.
How many bits is a VLAN ID?
12
VLAN identifier (VID) A 12-bit field specifying the VLAN to which the frame belongs. The values of 0 and 4095 (0x000 and 0xFFF in hexadecimal) are reserved. All other values may be used as VLAN identifiers, allowing up to 4,094 VLANs.
Is VLAN a protocol?
VLAN Trunking Protocol (VTP) is a Cisco proprietary protocol that propagates the definition of Virtual Local Area Networks (VLAN) on the whole local area network.
What is QinQ used for?
The general purpose of QinQ is to allow frames from multiple customers to be forwarded (or tunneled) through another topology (provider network) using service VLANs or S-VLANs.
How many VLANs are included in 802.1Q?
The 802.1q field includes the 12-bit VLAN ID field, which specifies the VLAN to which the frame belongs. 802.1q tagged frame can carry information for 4,094 VLANs. 802.1q defines one special VLAN ID on each trunk as the native VLAN (by default VLAN 1). 802.1q does not add an 802.1Q header to frames in the native VLAN.
What’s the difference between ISL and 802.1q?
Unlike ISL, which encapsulates the whole frame in an ISL header and trailer, 802.1q inserts an extra 4-byte 802.1q VLAN field into the original frame’s Ethernet header. The 802.1q field includes the 12-bit VLAN ID field, which specifies the VLAN to which the frame belongs. 802.1q tagged frame can carry information for 4,094 VLANs.
Can you use 802.1Q between different Cisco switches?
802.1q is a VLAN tagging protocols developed by IEEE (Institute of Electrical and Electronics Engineers). Since it is an open standard, it can be used between switches from different vendors, so if you’re trunking between a Cisco switch and a different brand of switch, you’ve can use 802.1q for the trunk to work.
Which is the IEEE 802.1Q tag termination feature?
The Q-in-Q VLAN tag termination feature is simpler than the IEEE 802.1Q tunneling feature deployed for the Catalyst 6500 series switches or the Catalyst 3550 and Catalyst 3750 switches. Whereas switches require IEEE 802.1Q tunnels on interfaces to carry double-tagged traffic,…