VTP and STP-ISL in VLAN

L3 and L4 exchanges are very mature. The exchange technology is also widely used in the Internet, and the full exchange network is already very common. VLAN usage is essential in these networks.

1. VLANVirtual LANs) Description

A VLAN is a switched network logically divided according to its role, plan group, and application. It has nothing to do with the user's physical location. For example, several terminals may be composed of one part, which may include engineers or financial personnel. When the actual physical location of the terminal is similar, a LAN can be formed ). If they are in different buildings, they can be aggregated through VLAN. The ports in the same VLAN can accept the broadcast packets in the VLAN. However, ports in other VLANs cannot be accepted.

VLAN provides the following features:

Simplifies the deletion, addition, and modification of terminals.

When a terminal is physically moved to a new location, its features can be redefined from the network management workstation through SNMP or the user interface menu. For terminals that only move in the same VLAN, it maintains the previously defined features. For terminals moving in different VLANs, the terminals can obtain new VLAN definitions.

* Control communication activities

A VLAN can consist of the same or different switch ports. The broadcast information is restricted in VLAN. This feature limits that only the ports in the VLAN can have broadcast and multicast communication. Management domain) is a collection of multiple VLANs with only one manager.

* Working Group and network security

Dividing networks into different domains can increase security. VLAN can limit the number of users in the broadcast domain. Controlling the size and composition of VLANs can control the corresponding features of broadcast domains.

VTP and STP are the most widely used VLAN technologies. They are a concentrated manifestation of the advantages of VLAN.

2. VTPVLAN Trunking Protocol)

VTP maintains VLAN configuration uniformity through the network. VTP adds, deletes, and adjusts VLANs in system-level management, and automatically broadcasts information to other switches in the network. In addition, VTP reduces the configurations that may cause security issues.

* When multiple name VLANs are used, the transaction can be changed *-connection.

* When they are incorrectly mapped to a LAN and other LAN, the VLAN can be switched to an internal disconnection.

VTP Mode

When a vswitch is in VTP Server or transparent mode, you can configure a vlan on the vswitch. When a vswitch is configured on a VTP Server or in a transparent mode, use the CLI, console menu, and MIB when using the SNMP Simple Network Management Protocol management workstation) to modify the VLAN configuration.

A vswitch configured in VTP Server mode broadcasts VLAN configurations to neighboring switches and learns new VLAN configurations from neighboring switches through its Trunk. In Server mode, you can use MIB, CLI, or Console mode to add, delete, and modify VLANs.

For example, if a VLAN is added, VTP broadcasts the new VLAN, And the Trunk Network Ports of the Server and Client are ready to receive information.

After the switch is automatically switched to the Client mode of VTP, it transmits broadcast information and learns new information from the broadcast. However, you cannot add, delete, or modify VLANs through MIB, CLI, or console. The VTP Client cannot keep VLAN information in non-Easy memory. When it is started, it receives broadcast information through the Trunk network port and learns the configuration information.

In VTP transparent mode, VLAN configurations are not broadcast or learned from the network. When a vswitch is in VTP transparent mode, you can use the console, CLI, and MIB to modify, add, and delete VLANs.

To make each VLAN usable, The VTP must be known. In the authorization list of the Trunk port, a fast Ethernet ISL Trunk automatically transmits data for a VLAN and transfers data from one switch to another.

It should be noted that if the exchange receives broadcast in VTP Server mode contains more than 128 VLANs, the switch is automatically switched to VTP Client mode.

Change the switch's transparent mode from VTP Client mode to VTP. The switch maintains the initial and unique VLAN and deletes the remaining VLAN.

Transmit VTP Information

Each vswitch uses VTP to broadcast the management domain of the Trunk port and define the specific VLAN boundary. Its Configuration revision number is known as VLAN and specific parameters. The switch can only work after a VTP management domain is registered.

Through Trunk, The VTP Server transmits information to other switches and receives updates. The VTP Server also saves the VLAN list in The VTP management domain information in NVRAM. VTP dynamically displays VLANs in the management domain through a unified name and internal list.

VTP information is transmitted over all Trunk connections, including ISL, 802.10, and LANE. Vtp mib provides SNMP tools for VTP and allows you to view VTP parameter configurations.

VTP creates shared configuration values and distributes the following shared configuration information:

* VLAN IDsISL)

* Use the LAN name atm lane)

* 10 said fddi)

* Maximum transmission unit MTU in VLAN

* Frame format

3. Spanning-Tree Protocol Spanning Tree Protocol)

STP can provide path redundancy, even if multiple valid paths in the Network may cause abnormal loops, resulting in abnormal network. Using STP can make two terminals have only one valid path.

STP defines a tree in a large network and forces a certain backup path to be In the Standby state. If part of the spanning tree is inaccessible or the STP value changes, the spanning-tree algorithm recalculates the spanning-tree topology and re-establishes a connection by starting the backup path. STP operations are transparent to terminals. The terminals are connected to either one or more parts of the LAN.

Configure the Spanning-Tree Protocol in different VLANs. When a network is created, multiple paths exist for all nodes in the network. The algorithm in the spanning-tree calculates the optimal path. Because each VLAN is a logical LAN, you can enable STP to work on a maximum of 64 VLANs at a time. To configure more than 64 VLANs, You need to disable STP for other VLANs. By default, STP supports 1-64 VLANs.

ISL protocol between switches
The ISL (Interior SwitchingLink) protocol is used to implement VLAN relay between switches. It is an information packet marking protocol. Frames sent on ISL interfaces are composed of a standard Ethernet frame and related VLAN information. You can transmit data from different VLANs on interfaces that support ISL.