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VLAN Cross Connect ( CC ) is a mechanism used to create Switched VLANs, VLAN CC uses IEEE 802. 1ad frames where the S Tag is used as a Label as in MPLS.
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Some Related Sentences
VLAN and is
One implementation of this concept is termed a " private VLAN ".
This is because a virtual LAN ( or VLAN ) is technically a broadcast domain.
In computer networking, virtual local area network, virtual LAN or VLAN is a concept of partitioning a physical network, so that distinct broadcast domains are created.
In an environment employing VLANs, a one-to-one relationship often exists between VLANs and IP subnets, although it is possible to have multiple subnets on one VLAN.
This " color " is what is now known in the Ethernet frame as the 802. 1Q header, or the VLAN tag.
Configuration of the first custom VLAN port group usually involves removing ports from the default VLAN, such that the first custom group of VLAN ports is actually the second VLAN on the device, in addition to the default VLAN.
It is only when the VLAN port group is to extend to another device that tagging is used.
Some switches either allow or require a name be created for the VLAN, but it is only the VLAN group number that is important from one switch to the next.
Where a VLAN group is to simply pass through an intermediate switch via two pass-through ports, only the two ports must be a member of the VLAN, and are tagged to pass both the required VLAN and the default VLAN on the intermediate switch.
If the default VLAN were deleted or renumbered without first moving the management connection to a different VLAN, it is possible for the technician to be locked out of the switch configuration, requiring a forced clearing of the device configuration ( possibly to the factory default ) to regain access.
VLAN and mechanism
* VLAN, for analogous mechanism in Ethernet
VLAN and used
In Ethernet, Virtual LANs ( VLAN ) may be used to separate different QoS levels.
One VLAN may be used for Internet access ( low priority ), one for IPTV ( higher priority ) and one for IP telephony ( highest priority ).
At the MAC layer, VLAN IEEE 802. 1Q and IEEE 802. 1p can be used to carry essentially the same information.
At the Media Access Control ( MAC ) layer, VLAN IEEE 802. 1Q and IEEE 802. 1p can be used to carry essentially the same information as used by DiffServ.
Inter-Switch Link ( ISL ) is a Cisco proprietary protocol used to interconnect multiple switches and maintain VLAN information as traffic travels between switches on trunk links.
With a VLAN Management Policy Server ( VMPS ), an administrator can assign switch ports to VLANs dynamically based on information such as the source MAC address of the device connected to the port or the username used to log onto that device.
With 802. 1q VLAN Tagging and QinQ the sparse 16-bit EtherType is being completely used.
This protocol can be configured globally or on a port, and can be used with IEEE 802. 1AB / LLDP or by itself for auto discovering the phones, setting VLAN PVID, Layer 2 and Layer 3 QoS values.
Port Mirroring is used on a network switch to send a copy of network packets seen on one switch port ( or an entire VLAN ) to a network monitoring connection on another switch port.
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.
When a frame enters the VLAN-aware portion of the network, a tag is added to represent the VLAN membership of the frame's port or the port / protocol combination, depending on whether port-based or port-and-protocol-based VLAN classification is being used.
The primary goal of VMPS is VLAN assignment for general network management purposes, but can also be used for providing security through segregating clients with an unknown MAC address, or through further extension of the protocol to provide login for Cisco AClS.
It is offered as an option to the IEEE 802. 1Q standard, a widely used VLAN tagging protocol, although the use of ISL for new sites is deprecated by Cisco.
* Fixes for VLAN and bonding when libnl2 or earlier are used
VLAN and VLANs
Simpler devices only support partitioning on a port level ( if at all ), so sharing VLANs across devices requires running dedicated cabling for each VLAN.
However, unlike physically separate networks, VLANs share bandwidth, so VLAN trunks may require aggregated links and / or quality of service priorization.
By definition, switches may not bridge IP traffic between VLANs as it would violate the integrity of the VLAN broadcast domain.
A basic switch not configured for VLANs has VLAN functionality disabled or permanently enabled with a default VLAN that contains all ports on the device as members.
The IEEE committee defined this method of multiplexing VLANs in an effort to provide multivendor VLAN support.
Cisco also implemented VLANs over FDDI by carrying VLAN information in an IEEE 802. 10 frame header, contrary to the purpose of the IEEE 802. 10 standard.
Cisco switches run an instance of STP for each VLAN, and since VTP propagates VLANs across the campus LAN, VTP effectively creates more opportunities for a bridging loop to occur.
** Cisco home page for Virtual LANs / VLAN Trunking Protocol ( VLANs / VTP ) ( discusses DSL, DTP, GVRP, ISL, VTP, 802. 1Q )
VLANs have to be on a Sub-Interface, It is best practice to match the Sub-Interface # and the VLAN #
VLANs have to be on a Sub-Interface, It is best practice to match the Sub-Interface # and the VLAN #
After the frames are transmitted on their respective VLANs through the corporate network, the VLAN tag is stripped before the frame leaves the VLAN-aware corporate network, and is sent to its destination, which is another computer belonging to the same department.
* Scalability: In a properly designed Ethernet VLAN network, each switched path can have 4094 single tag VLANs.
Some aggregation and core switches can classify traffic by two VLANs using IEEE 802. 1ad VLAN stacking, so with such aggregation devices properly placed in the center of a network, end segments and rings of single tag devices can receive only the traffic that they need.
VLAN and IEEE
Both ISL and IEEE 802. 1Q tagging perform " explicit tagging "-the frame itself is tagged with VLAN information.
* From OSI layer 2, 3 or 4 to IP DSCP ( if IP packet ) and / or VLAN IEEE 802. 1p.
* From VLAN IEEE 802. 1p to IP DSCP.
* From IP DSCP to VLAN IEEE 802. 1p.
* From VLAN IEEE 802. 1p to port queue.
* VLAN tagging IEEE 802. 1q
The most common and preferred method, IEEE 802. 1Q adds a tag to the Ethernet frame, labeling it as belonging to a certain VLAN.
Enables IEEE 802. 1Q VLAN frame tagging, followed by the VLAN # that this sub-interface will route
Enables IEEE 802. 1Q VLAN frame tagging, followed by the VLAN # that this sub-interface will route
The RPR standard also supports the use of learning bridges ( IEEE 802. 1D ) to further enhance efficiency in point to multipoint applications and VLAN tagging ( IEEE 802. 1Q ).
* VLAN Identifier, a data field in IEEE 802. 1Q VLAN tagging
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