In the star network structure, each node is connected to a central node device (such as a hub, switch) in a point-to-point manner, and the data sent by each node needs to be transmitted to the destination node after passing through the central node device.
As shown in Figure 5-8, the star structure is the most widely usedWebsite constructionOne of the topology designs.
The network with this topology requires high reliability of the central node, otherwise, once a failure occurs, the entire network will be endangered.
1. Star topology characteristics
(1) The network structure is simple, management is convenient, and implementation is easy. (2) The communication medium is twisted pair, and RJ-45 interface standard is used at both ends. (3) The transmission distance is up to 100 meters, the network delay time is short, and the bit error rate is low (4) The media access method adopts the CSMA/CD protocol of Ethernet.
2. Disadvantages of star topology
(1) The cost of the line is increased and the utilization rate of the line is not high. (2) High reliability requirements for the central node.
3. Central node equipment
The central node equipment of star topology can be either a hub or a switch. The two networks have the same appearance, but the network communication performance is essentially different.
A star topology network constructed by a hub. All nodes share the total bandwidth of the hub. At the same time, only two nodes can communicate with each other. The communication mode can only be half duplex. The hub is a physical layer device. Its internal communication mechanism is not fundamentally different from the traditional bus Ethernet, but its topology has changed from bus to star,The communication medium is changed from coaxial thin cable to twisted pair.Therefore, the star network built by 10M low-speed hub is often called traditional star Ethernet.
For the star topology network built by the switch, all nodes share their own interface bandwidth of the switch, and the communication mode can be full duplex.The switch is a data link layer device, and its built-in back bus bandwidth is sufficient to meet the communication bandwidth requirements of each node. Therefore, several node groups can communicate at the same time,Website construction outsourcingWithout conflict.
4. Common star topology network
1) Traditional star Ethernet
Features of traditional star Ethernet:
(1) The central node device is the lOBase hub.
(2) Category 3 twisted pair is used as communication medium, with transmission rate of 10Mbps and maximum transmission distance of 100m.Such as 10Base-T standard Ethernet.
2) Fast Ethernet
Features of Fast Ethernet:
(1) The central node device is a 100 Base hub and a 100 Base switch.
(2) Category 5 twisted pair is used as communication medium, with transmission rate of 100Mbps and maximum transmission distance of 100m.
In 100Base standard Ethernet, if the central node equipment uses 10OBase hub, this fast Ethernet can only work in half duplex mode;If the central node equipment uses a 100Base switch, Fast Ethernet can support both full duplex and half duplex modes, and there is no conflict in full duplex mode.When the central node equipment is a switch, it can also be called switched Ethernet.