Appendix 1. Ethernet Control LAN Network Construction Guide
38
Shared Hub: (A “Hub” refer to a shared hub.)
It is called a Multiport Repeater in IEEE802.3u. It doesn’t have functions such as filtering and switching.
Frames input to one port are repeated to all the other ports.
The following figure illustrates the data flow when data is sent from Station A to Station B if a shared hub is
used.
Data is sent from Station A to Shared Hub First Port.
In the Shared Hub, data received from the first port is repeated to the other ports.
Data is sent from the Shared Hub 4th Port to Station B.
1 2 3 4 5 6 7 8
E E EE E EE E
Shared Hub
LAN Control LSI
RJ-45Connector
Station A Station B
Station C Station D
Figure A1.19 Operations of a Shared Hub
As shown in the figure above, C and D cannot communicate while A and B are communicating for a shared
hub, while C and D can communicate while A and B are communicating for a switching hub. When A and
C send data at the same time for the shared hub, a collision is detected.
The relations between communication modes and hub types are the following: For a switching hub, ports
can be full-duplex because data is temporarily stored in the buffer; for a shared hub, communication is
half-duplex since send and receive cannot be performed simultaneously, as shown in the figure above.
To Next Page
Loading...
Need help?
General
