CCNA ICND2 Flash Cards

To create more flexible designs that group users by department, or by groups that work together, instead of by physical location
To segment devices into smaller LANs (broadcast domains) to reduce overhead caused to each host in the VLAN
To reduce the workload for the Spanning Tree Protocol (STP) by limiting a VLAN to a single access switch
To enforce better security by keeping hosts that work with sensitive data on a separate VLAN
To separate traffic sent by an IP phone from traffic sent by PCs connected to the phones

When a sending switch adds another header to the frame before sending it over the trunk connection.

The use of trunking allows switches to pass frames from multiple VLANs over a single physical connection.

Switch1 sends a frame from VLAN 1 to Switch2 before sending the frame Switch1 adds another header to the frame specifying the VLAN ID so Switch2 knows this frame belongs to a VLAN1 Switch 2 recieves the frame decapsulates the header and sees that the frame belongs to VLAN1, so Switch 2 floods the frame out all interfaces belonging to VLAN1 instead of ALL interfaces on the switch.

ISL - Inter-Switch Link 802.1Q

Inter-Switch Link is a Cisco proprietary trunking protocol that encapsulates an entire ehternet frame with a new header and trailer whose main purpose is to specify the VLAN number in the header.

802.1Q is an IEEE trunking protocol that inserts an additional 4 bit header to the original ethernet frame instead of encapsulating the original frame to specify the VLAN ID of a frame.

Native VLAN is a 802.1Q concept that specifies a certain specific VLAN on a switch as the native VLAN and does not add 802.1Q headers to frames passed through that VLAN. The main use for native VLANs is to provide a connection to devices that dont understand trunking.

1-1005

1006-4094

VLANs must be in seperate subnets in order to forward packets to hosts in other subnets. Each VLAN is assigned a specific subnet and in turn forwards the frame to a router for a packet destined to a different subnet. The router processes the frame and forwards the packet out the same incoming interface but specifies the different VLAN ID in the header so its routed properly to that device. Most networks today have devices called multilayer switches to perform this same logic without the use of a router.

VLAN Trunking Protocol provides a means by which cisco switches can exchange VLAN configuration information similar to how routing protocols advertise and learn about new route connections on a WAN or LAN.

Server, Client, and Transparent mode

You can't but you can set all switches to use transparent mode so they dont create or send out any VLAN trunk headers on any frames in the network. Its more like passively disabling it rather then turning it off completely.

When a VTP update is recieved with an incremented VLAN database configuration revision number from the VLAN server.