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D-Link DGS-1005D Unmanaged Gigabit Ethernet Switch
SECTION 1
Introduction
Ethernet Technology
802.1p and QoS
D-Link’s Green Technology
Switch Description
Features
Ports
Front-Panel Components
Ethernet Technology
Fast Ethernet Technology
The growing importance of LANs and the increasing complexity of desktop computing applications are fueling the need
for high performance networks. A number of high-speed LAN technologies are proposed to provide greater bandwidth and
improve client/server response times. Among them, Fast Ethernet, or 100BASE-T, provides a non-disruptive, smooth
evolution from 10BASE-T technology.
100Mbps Fast Ethernet is a standard specified by the IEEE 802.3 LAN committee. It is an extension of the 10Mbps
Ethernet standard with the ability to transmit and receive data at 100Mbps, while maintaining the Carrier Sense Multiple
Access with Collision Detection (CSMA/CD) Ethernet protocol.
Gigabit Ethernet Technology
Gigabit Ethernet is an extension of IEEE 802.3 Ethernet utilizing the same packet structure, format, and support for
CSMA/CD protocol, full duplex, flow control, and management objects, but with a tenfold increase in theoretical
throughput over 100Mbps Fast Ethernet and a one hundred-fold increase over 10Mbps Ethernet. Since it is compatible with
all 10Mbps and 100Mbps Ethernet environments, Gigabit Ethernet provides a straightforward upgrade without wasting a
company’s existing investment in hardware, software, and trained personnel.
The increased speed and extra bandwidth offered by Gigabit Ethernet are essential to coping with the network bottlenecks
that frequently develop as computers and their busses get faster and more users use applications that generate more traffic.
Upgrading key components, such as your backbone and servers to Gigabit Ethernet can greatly improve network response
times as well as significantly speed up the traffic between your subnetworks.
Gigabit Ethernet enables fast optical fiber connections to support video conferencing, complex imaging, and similar data-
intensive applications. Likewise, since data transfers occur 10 times faster than Fast Ethernet, servers outfitted with Gigabit
Ethernet NIC’s are able to perform 10 times the number of operations in the same amount of time.
In addition, the phenomenal bandwidth delivered by Gigabit Ethernet is the most cost-effective method to take advantage
of today and tomorrow’s rapidly improving switching and routing internetworking technologies.
802.1p and QoS
The DGS-1005D Switch supports 802.1p priority queuing Quality of Service. The implementation of QoS (Quality of
Service) and benefits of using 802.1p priority queuing are described here.
Advantages of QoS
QoS is an implementation of the IEEE 802.1p standard that allows network administrators a method of reserving
bandwidth for important functions that require a large bandwidth or have a high priority, such as VoIP (voice-over Internet
Protocol), web browsing applications, file server applications or video conferencing. Not only can a larger bandwidth be
created, but other less critical traffic can be limited, so bandwidth can be saved. The Switch has separate hardware queues
on every physical port to which packets from various applications are mapped to and assigned a priority. The illustration
below shows how 802.1P priority queuing is implemented on the Switch. The eight IEEE 802.1P priority levels defined by
the standard are mapped to the four class queues used in the Switch.