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General
Questions
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Q12:
What
is the twisted-pair cable for Gigabit Ethernet?
Q11: Is
the Twisted-Pair Gigabit Port auto-negotiation in speed and
operation mode?
Q10: What
is Auto MDI/MDI-X function?
Q09:
What
is the MAC address table of a Gigabit Switch?
Q08:
What
is Filtering and Forwarding of a Gigabit Switch?
Q07:
What
is Store and Forward of a Gigabit Switch?
Q06:
What
is 802.1Q VLAN?
Q05:
What
is Port Based VLAN?
Q04:
What
is Port Aggregation (Port Trunk)?
Q03:
What
is Spanning Tree Algorithm (STA)?
Q02:
What
is CoS Priority?
Q01:
What
is Port mirror of a Gigabit Switch?
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Q12:
What is the twisted-pair cable for Gigabit Ethernet?
Ethernet,
Fast Ethernet and Gigabit Ethernet use the following types of
cabling:
10Mbps:
10BASE-T: Category 3, 4 or 5 UTP/STP
100Mbps: 100BASE-TX: Category 5
UTP/STP
1000Mbps:
1000BASE-T: Category 5 UTP/STP
Category
5 cable is preferred to be using with twisted-pair Ethernet in
structured wiring environments. This will ensure correct operation
of all ports at 10Mbps, 100Mbps or 1000Mbps.
Note
that for Gigabit Ethernet, all 4 pairs of the twisted-pair cable are
used for transmission and receiving signals.
While
for 10Mbps and 100Mbps, only 2 pairs (ping-1,2 and pin-3,6) are
used.
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Q11:
Is the Twisted-Pair Gigabit Port auto-negotiation in speed and operation
mode?
Yes,
the auto-negotiation feature of the Gigabit switch and card allows
each port of the device running at one of the following operation
modes:
|
Port |
Speed |
Duplex
Mode |
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Gigabit |
1000
Mbps |
Full-duplex |
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100
Mbps |
Full
duplex
Half duplex |
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10
Mbps |
Full
duplex
Half duplex |
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Q10:
What is Auto MDI/MDI-X function?
When
switch UTP port or LAN card supports auto MDI/MDI-X function, the
connection is independent of cables crossover or non-crossover
type and allows using a straight cable to make a switch-to-switch
connection.
For
Station connection:
Connect
each station to the switch by a category 5 twisted-pair cable
(straight or cross-over cable). Plug one RJ-45 connector into a
front-panel port of the switch, and plug the other RJ-45 connector
into the stations network adapter.
For
Switch-To-Switch connection:
In
making a switch-to-switch connection, you could use any port to
connect another switch with straight or crossover cable.
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Q09:
What is the MAC address table of a Gigabit Switch?
The
switch is implemented with a MAC address table, which is composed of
many entries. Each entry is used to store the address information of
network nodes on the network, including MAC address, port ID, etc.
The information is the most important base to do packet filtering
and forwarding.
When
one packet comes in from any port, the switch will learn the source
address, port ID, and the other related information in address
table. Therefore, the content of the MAC table will update
dynamically.
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Q08:
What
is Filtering and Forwarding of a Gigabit Switch?
When
one packet comes in from any port of the switch, it will check the
destination address besides the source address learning. The switch
will look up the address table for the destination address. If not
found, this packet will be forwarded to all the other ports except
the port where the packet comes in. If found, and the destination
address is located at different port from this packet comes in, the
packet will be forwarded to the port where this destination address
is located according to the information of address table. But, if
the destination address is located at the same port as this packet
comes in, this packet will be filtered.
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Q07:
What
is Store and Forward of a Gigabit Switch?
Store-and-forward
is one kind of packet-forwarding methodology. As a store-and-forward
switch, it will store the complete packet in the internal buffer and
do the complete error checking before transmitting to the network.
Therefore, no error packets will disturb the network. It is the best
choice when a network needs efficiency and stability.
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Q06:
What is 802.1Q VLAN?
The
Virtual LAN (VLAN) function is a group of ports that may spread
around the network but communicate as though they belong to one
subnet. By using IEEE 802.1Q compliant VLAN, all ports can be
reorganized into separate broadcast domains for security reasons and
reduce bandwidth occupation instead of using routers to divide whole
network into subnets. It produces cleaner network environment by
reducing broadcast traffic and simplify network management by
allowing you to move devices to another VLAN without changing
physical connections.
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Q05:
What
is Port Based VLAN?
The
Port Group VLAN (Port-based VLAN) is concentrate on definite ports.
The packets forwarding policies are based on destination MAC
addresses or related ports by voluntary learning relationship of MAC
addresses and its related ports.
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Q04:
What is Port Aggregation (Port Trunk)?
Port
Aggregation (Port Trunk) is used to increase the bandwidth of a
switch-to-switch connection and backup. For example, when switches
provide 7 port aggregation groups, which consist of 4 ports and
create bandwidth up to 800Mbps per group. If the group of 2 Gigabit
ports that creates bandwidth up to 4Gbps at full duplex mode.
When
two switches be set with Port Trunk function, the wires between that
two switches must be connected 4 cables at the same time in
one-to-one bassis.
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Q03:
What is Spanning Tree Algorithm (STA)?
The
Spanning Tree Algorithm (STA) outlined in IEEE 802.1D can avoid
network looping but coexist with linking backup. This feature
permits STA-aware switches interact with each other. This can ensure
only one route exists between any two devices on the network. If
looping is detected (maybe implements on purpose for linking
backup), looping ports will be blocked to discard additional route.
If one using route fails, this Spanning Tree Algorithm automatically
releases the blocking port and establishes connection with other
devices.
Since
a STA network has been established, all devices listen for Hello
BPDUs (Bridge Protocol Data Units) sent from the Root Bridge. After
the Max Age maximum time is up, the device supposes that the route
to the Root Bridge is down. The devices initiate negotiations with
each other to reconfigure the network for a valid topology.
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Q02:
What is CoS Priority?
When
a Gigabit switch supports IEEE802.1p CoS with 2-level priority.
There are 8 traffic classes and 8 Service Rules in the Priority Map.
When one packet carries with priority-tag, which has specified a CoS
(Class of Service) comes into the switch, the specified CoS tag will
determine what priority (Low/High) will it get according to the
Priority Map in the switch.
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Q01:
What is Port mirror of a Gigabit Switch?
Port
mirror is used to mirror traffic from source port to a target port
for analysis. Only 2 ports can be monitored (mirrored)
simultaneously to 1 sniffer port (target port). (Note that the
target port must be in the same VLAN as the source port)
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EUSSO
Technologies, Inc. is a dedicated data communication and networking
company. With professional experiences in design, production,
marketing and service support, we deliver the full range networking
products including Gigabit Ethernet, Fiber Optic, Wireless LAN,
Switches, Hubs, LAN cards, PCMCIA adapters, Converter, Transceivers.
As well as Internet Telephony Gateway, Print Servers, Broadband Router
and many others.
Copyright
EUSSO Technologies, Inc. 2003
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UGS5224-RM