What is ring topology _Shang ping China focuses on high quality website construction - 上海1314龙凤鲜花坊_上海419贵族宝贝

In the ring network structure, each node is connected to a closed ring channel through a ring connector, and each node in the ring has the same status. The ring network has a single ring structure and a double ring structure, and data is always transmitted in one direction on the ring, as shown in Figure 5-7.

Token ring network is a kind of LAN with this structure, which is defined in IEEE 802 5 in the standard. In token ring network, the medium access method is token ring protocol.

1. Token Ring Protocol

In the token ring network, a small data frame is transmitted all the time, which is called "token". For all nodes on the ring, the node sending data must first intercept the token, and then have the authority to send data. After the data is sent, the token must be released to the ring.

If a node on the ring needs to send data, the node must first intercept the token, then change the token attribute (which means that it is not a token at this time, but a data frame), add the data to be transmitted to the data frame that changes the token attribute, and form a data frame and send it to the ring. When the data frame is transmitted on the ring, Website production There is no token in, which means that other nodes can only wait to transmit data. Therefore, there will be no data conflict in the token ring network. Data frames are transmitted along the ring. After arriving at the destination node, a copy of the destination node's COPY data frame is transmitted to the upper layer of the node. At the same time, the data pause state (indicating that the data has been received) is changed and sent back to the ring. The data frame with changed status continues to be transmitted along the loop until it reaches the source sending node. The sending node checks the returned data frame status to determine whether it is correctly received by the destination node, or it will re send.

2. Features of Token Ring

(1) In the point-to-point channel, all nodes have equal status, and there is no central node control. Data is always transmitted from the sending node interface Marketing website construction One end is transmitted along one direction of the ring, and the other end of the sending node interface waits for data and retracts it.

(2) The communication medium is generally coaxial cable, and the medium access method is IEEE 802 5 Token ring protocol, the transmission rate is 4Mbps or 16Mbps.

(3) The transmission bit error rate is low, and there is no data conflict.

3. Token ring defects

(1) It is difficult to expand or reconstruct, and the process of adding and withdrawing nodes is complex.

(2) There is a delay problem, which is not suitable for real-time applications.

(3) When the load is very low, the channel utilization is relatively low.

(4) The token needs to be maintained. Once the token is lost, it cannot work. Therefore, a special node monitoring and management token needs to be selected.

(5) The reliability of each node interface and link is required to be high. Once a failure occurs, the whole network will be paralyzed.

Due to the rapid development of Ethernet technology, token ring network has also been eliminated or rare in the whole LAN network.

What is a ring topology

Date：2015-07-14 Source: Shangpin China Type: website encyclopedia
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