ISL encapsulates the original Ethernet frame, and a VLAN-ID is inserted into the ISL header among several other fields. Inter-Switch Link (ISL) is a Cisco proprietary VLAN trunking protocols, used for switched VLAN networks. 1q allows you to send untagged frames on a trunk link provided, your end devices (routers and switches) know which vlan they belong to. If an untagged frame is received they should ideally discard it, however. Note: Trunk ports send and receive tagged frames always. Normal VLAN traffic: All normal VLAN traffic (other than native vlan) will have a VLAN tag (.1q tag) attached while traversing the trunk ports. By default, VLAN 1 is management VLAN in Cisco switches.Ĥ. Management VLAN: it is the native vlan used for in-band management (SNMP trap source, syslog source interface, telnet, ssh access to a device). Port Mode Encapsulation Status Native vlanĢ. You may verify the native vlan using the show command: (config-if)#switchport trunk native vlan 2 However, you may change the native VLAN to any other number by using the following command: Default VLAN: It is the the native VLAN that is used for management functions by default it is VLAN 1. Different terms are as explained below:ġ.
Once the native VLAN is changed (to say, VLAN 2) the the management VLAN will be VLAN2. However, you may change the native VLAN to some other number (from VLAN 1) for security reasons. VLAN 1 is the default and native VLAN that is used for management functions. By default, all three are one and the same. There are different types of VLANs, viz Native VLAN, Management VLAN, and Default VLAN which may be confusing. For example, if you want to see the configuration information for vlan2, you give the command " sh vlan 2 The command " sh vlan" will display the configuration information for all VLANs, where as the command " sh vlan vlan#" shows only the configuration information pertaining to that vlan. You use " show vlan" or " show vlan vlan#" command to see the configuration details of VLANs.
The packet forwarding between VLANs is achieved through the use of routing. However, when you use switches and implement VLANs, each VLAN will be in a separate broadcast domain. When you use Hubs, all the nodes connected to the hub will be in the same collision domain. It is important to know the difference between a collision domain and a broadcast domain. This is an IEEE standard for transporting frames over ATM networks. LANE: LANE stands for LAN Emulation and is associated with ATM. 802.10: A Cisco proprietary method for transporting VLAN information inside the standard 802.10 FDDI frames.Ĥ. A VLAN identifier is inserted into the frame header, a technique called frame tagging.ģ. 802.1Q: This is an IEEE standard for the VLAN trunking protocols, associated with Ethernet. Supported by Catalyst switches and routers.Ģ. ISL: A Cisco proprietary trunking protocol, associated with Ethernet. Distribution of traffic thereby using the network bandwidth more efficiently.ġ. Grouping based on functional requirements irrespective of physical location of nodes, Simplify moves, adds, changes,Ĥ. Increased Security due to broadcast control, if you are using simple hub, you can observe traffic corresponding to any node by simply inserting a Network analyzer.ģ. Easy Administration resulting in reduced administration costs,Ģ. Note that switches can maintain an IP stack, which enables us to manage the switches either locally, as well as remotely by Telnet.įrame tagging is a technique used to uniquely identify a frame as it is forwarded through the switch fabric.ġ. The subnet portion of the switch IP address must match the subnet number of the management VLAN. To associate a switch with a management VLAN, you need to assign an IP address to the switch. A VLAN operating on a Catalyst switch limits transmission of unicast, multicast, and broadcast traffic to only the other ports belonging to that VLAN, thereby controlling broadcasts. Using VLAN technology, you can group switch ports and their connected users into logically defined communities of interest. Like routers, switches (Layer 2) have the ability to provide domain broadcast segmentation called a VLAN. All devices working on a VLAN will have same broadcast domain. Layer2 Technologies 1.3 Configure and Verify VLANsĪ VLAN is a group of devices on one or more logically segmented LANs.