Carrier Sense Multiple Access/Collision Detection
CSMA/CD is a Media Access
Control (MAC) protocol that defines how network devices respond when two
devices attempt to use a data channel simultaneously and encounter a data
collision.
The CSMA/CD rules define how long the device should wait if a
collision occurs. The medium is often used by multiple data nodes, so each data
node receives transmissions from each of the other nodes on the medium.
There
are several CSMA access modes:
1-persistent, P-persistent and O-persistent.
- 1-persistent is used in CSMA/CD systems, like Ethernet.This mode waits for the medium to be idle, then transmits data.
- P-persistent
is used in CSMA/CA systems, like Wi-Fi.This mode waits for the medium to be
idle, then transmits data with a probability p.
- O-persistent is used by CobraNet, LonWorks, and the controller area network. This mode assigns a transmission order to each data node. When the medium becomes idle, the data node next in line is able to transmit data. The data node next in line waits for the medium to be idle again and then transmits its data. After each data node transmits data, the transmission order is updated to reflect what data nodes have already transmitted, moving each data node through the queue.
Metadata Management - With thousands of data attributes, delivered by hundreds of internal and external sources and stored in dozens of unconnected databases, we saw the need for a web-based solution that was capable of integrating the multiple business and technical tools currently in use by financial organizations. That is why we decided to work exclusively with Adaptive who has helped us migrate our Semantics Repository to their standards-based Metadata Manager.
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