Q4 
How does Gigabit Ethernet
fit into existing networks? |
|
| The
Gigabit Ethernet technology will be fully
compatible with existing networks and preserve
user investments in applications, network
operating systems, protocols, and network
management. The Gigabit Ethernet will preserve
the IEEE802.3 and Ethernet frame format, and
the IEEE802.3 managed object specifications.
Therefore, users can migrate easily to Gigabit
speeds with existing applications, network
operating systems, protocols, and network
management. The Gigabit Ethernet will provide
increased bandwidth in those portions of the
network where it is needed, while exhibiting
seamless integration with a customer's existing
Ethernet infrastructure. |
|
|
|
| Q5
What is the major reason to replace the Fast
Ethernet Switch with Gigabit Ethernet Switch? |
|
| The
most important reason to implement Gigabit
solutions are at the data center (or backbone)
and between the workgroup and the data center.
Essentially, any switch-to-switch connections
in the network should be Gigabit. This allows
PCs using 10/100 adapter cards to turn on
to 100 Mbps without creating a bottleneck
in the backbone. Busy data center servers
should also be equipped with Gigabit adapter
cards. This prevents server-to-switch bottlenecks
and enhances the performance of 100 Mbps clients
requesting data from the servers. As the demand
for bandwidth grows, especially for those
running graphics and multimedia applications,
it is imaginable that Gigabit will run to
the desktop. |
|
 |
|
| Q6 Can
my existing Cat 5 cable be used for Gigabit
switch? |
|
| Yes.
The IEEE 1000Base-T specification supports
the use of Cat 5, or enhanced Cat 5 cable,
for successful gigabit transmission running
Gigabit Ethernet on Cat 5 cabling is easier
than wiring for 10/100M bit/sec Ethernet.
The 1000Base-T specification provides for
the automatic negotiation of link characteristics,
including automatic crossed cable correction.
Automatic negotiation enables successful cable
connections between 1000Base-T network interface
cards (NIC), hubs, switches or other devices
that may operate at half-duplex when the ports
are initialized. |
|
|
|
| Q7
How to do the firmware
upgrade of Repotec Gigabit Switch? |
|
| The
Web management utility provides firmware upgrade
function. User can easily upgrade the new
firmware through the web management utility.
Please check REPOTEC Website for latest firmware. |
|
|
|
| Q8
What¡¦re the cabling and distance limitations
for Gigabit Ethernet? |
|
| GE Type |
Wiring Type |
Cable Length |
| 1000BaseCX |
Shielded Twisted Pair(STP) |
25m |
| 1000BaseT |
EIA/TIA Category 5 UTP |
100m |
| 1000BaseSX |
Multimode fiber(MMF)with 62.5 micron
core;850 nm laser |
275m |
| |
MMF with 50 micron core;1300 nm laser |
550m |
| 1000BaseLX |
MMF with 62.5 micron core;1300 nm
laser |
550m |
| |
Single-mode fiber(SMF) with 50 micron
core; 1300 nm laser |
550m |
| |
SMF with 9 micron core;1300 nm laser |
10km |
|
|
|
|
| Q9
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) |
|
|
|
| Q10
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. |
|
|
|
| Q11
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. |
|
|
|
| Q12
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. |
|
|
|
| Q13
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 |
|
|
|
| Q14
What is Switch? |
|
| Switch
is a device that filters and forwards packets
between LAN segments. Switches operate at
the data link layer (layer 2) and sometimes
the network layer (layer 3) of the OSI Reference
Model and therefore support any packet protocol.
LANs that use switches to join segments are
called switched LANs or, in the case of Ethernet
networks, switched Ethernet LANs. |
|
|
|
| Q15
What's the difference
between Hub and Switch? |
|
| A switch
operates at layer 2 and just transmits the
packets to the port which the destination
address exist so that it separates each port
into several collision domains. The port-to-port
bandwidth is dedicated. On the other hand,
a hub transmits packets to all ports. The
port-to-port bandwidth is shared. |
|
|
|
| Q16
What is a ¡§Stackable Management Switch¡¨? |
|
| A
¡§stackable management switch¡¨ is a switch
design which enables more than one switches
can be ¡§stacked¡¨ together for management.
When managing these switches from management
user interface, they are stacked together,
but physically they can be separated in different
locations and linked by ¡§stackable¡¨ cables.
Note that the stackable TP cable is for management
information flow, not the same as ¡§stackable
switch¡¨ for data flow. Meanwhile, the ¡§stackable
management¡¨ switches can be or not necessary
to be cascaded by data links. |
|
|
|
| Q17
What is Web-based Management switch? |
|
| A device
(Hub, Switch or Router) embedded web-based
(hypertext) interface allows users to manage
the device from anywhere on the network through
a standard browser such as Netscape Navigator/Communicator
or Microsoft Internet Explorer. The web-browser
acts as a universal access tool and can communicate
directly with the device using HTTP protocol.
|
|
|
|
| Q18
What is port trunk? |
|
| Port
trunk allows multiple links to be bundled
together and act as a single physical link
for increased throughput. It provides load
balancing, and redundancy of links in a switched
inter-network. The link does not have an inherent
total bandwidth equal to the sum of its component
physical links. Instead, traffic in a trunk
is distributed across an individual link within
the trunk in a deterministic method, so-called
a hash algorithm. Traffic pattern on the network
should be considered carefully. When a proper
hash algorithm is used, traffic is randomly
decided to be transmitted across either link
within the trunk and load balancing will be
seen. |
|
|
|
| Q19
What is VLAN? |
|
|
Virtual LAN,
a network of computers that behave as if they
are connected to the same wire even though
they may actually be physically located on
different segments of a LAN. VLANs are configured
through software rather than hardware, which
makes them extremely flexible. One of the
biggest advantages of VLANs is that when a
computer is physically moved to another location,
it can stay on the same VLAN without any hardware.
|
|
|
|
| Q20
What
is Qos? |
|
| Quality
of Service, a networking term that specifies
a guaranteed throughput level. One of the
biggest advantages of ATM over competing technologies
such as Frame Relay and Fast Ethernet, is
that it supports QoS levels. This allows ATM
providers to guarantee to their customers
that end-to-end latency will not exceed a
specified level. |
|
|
|
| Q21 When
should I use Gigabit switch? |
|
| The
most important place to implement Gigabit
solutions are at the data center (or backbone)
and between the workgroup and the data center.
Essentially, switch-to-switch connections
in the network should be Gigabit. This allows
PCs using 10/100 adapter cards to turn on
to 100 Mbps without creating a bottleneck
in the backbone. Busy data center servers
should also be equipped with Gigabit adapter
cards. This prevents server-to-switch bottlenecks
and enhances the performance of 100 Mbps clients
requesting data from the servers. As the demand
for bandwidth grows, especially for those
running graphics and multimedia applications,
it is imaginable that Gigabit will run to
the desktop. |
|
|
|
| Q22Can
user use existing Category 5 cable for Gigabit
switch? Yes |
|
| The
IEEE 1000BASE-T specification supports the
use of Category 5, or enhanced Category 5
cable, for successful gigabit transmission
running Gigabit Ethernet on Category 5 cabling
is easier than wiring for 10/100M bit/sec
Ethernet. The 1000BASE-T specification provides
for the automatic negotiation of link characteristics,
including automatic crossed cable correction.
Automatic negotiation enables successful cable
connections between 1000BASE-T network interface
cards (Network Card), hubs, switches or other
devices that may operate at half-duplex when
the ports are initialized. |
|
|
|
| Q23
What kind of security
of switches provided or supported? |
|
There
are two ways to use a switch to improve network
security:
VLAN: A network administrator can define several
VLANs and block access to each VLAN to prevent
users from accessing servers for which they
don't have access permission.
Mac address filtering: A network administrator
can define a DA (Destination Address) so that
packets can only be received from port A (a
hub) and only allow those same packets to
be forwarded to port B (a server connection,
for example). Using MAC address filtering,
only users that are connected to port A can
access the server connected to port B, other
packets from other ports, even those whose
DA is for the server on port B, will be dropped. |
|
|
|
| Q24
What
is Hub? |
|
Hub
is a common connection point for devices in
a network. Hubs are commonly used to connect
segments of a LAN. A hub contains multiple
ports. When a packet arrives at one port,
it is copied to the other ports so that all
segments of the LAN can see all packets.
A passive hub serves simply as a conduit for
the data, enabling it to go from one device
(or segment) to another. So-called intelligent
hubs include additional features that enable
an administrator to monitor the traffic passing
through the hub and to configure each port
in the hub. Intelligent hubs are also called
manageable hubs.
A third type of hub, called a switching hub,
actually reads the destination address of
each packet and then forwards the packet to
the correct port.
A hub includes a series of ports that each
accepts a network cable. Small hubs network
four computers. They contain four or sometimes
five ports, the fifth port being reserved
for "uplink" connections to another
hub or similar device. Larger hubs contain
eight, 12, 16, and even 24 ports.
Hubs offer a convenient, affordable way to
build a home or small business network. Several
manufacturers produce hubs in varying port
configurations, but even the most basic hubs
can provide satisfactory file sharing and
Internet connection sharing for a small LAN. |
|
|
|
| Q25
Which Hub is right
for me? |
|
A number of different factors determine the
usefulness of a hub:
¡E the number of ports it features
¡E the bandwidth rating
¡E the manufacturer and their reputation for
quality
For many home networks, a 4~8-port hub will
be sufficient to build a LAN. 5-port hubs,
with their "uplink" capability,
offer a good compromise between up-front cost
and future extensibility. The basic hubs support
10 Mbps Ethernet. 10 Mbps will support basic
sharing either of traditional dial-up, cable
modem, and DSL Internet service.
So-called 10/100 hubs support
both 10 Mbps (traditional Ethernet) and
100 Mbps (Fast Ethernet) connections. These
higher-performance hubs can prove very useful
in some situations. For example, online
gamers who enjoy "LAN parties"
and home multiplayer gaming will almost
certainly notice a significant performance
increase when running at 100 Mbps. Note
that to network at this speed, both the
hub and the network interface card (NIC)
on the computer must be rated at either
10/100 Mbps or 100 Mbps. . |
|
|
|
| Q26
What
is the difference between Hub and Switching
Hub? |
|
| Each
port of the switch has a dedicated bandwidth
of the network. Hub is a device for shared
media, all ports of the hub share a single
bandwidth of the network. Hub is a multi-port
repeater without error checking, whereas switch
is a multi-port bridge with error checking. |
|
|
|
| Q27
What¡¦s
the maximum number of HUBs to be cascaded
in a network? How about switch? |
|
| In an
Ethernet environment, only 4 non-stackable
Hubs can be cascaded at most. In Fast Ethernet
environment, only 2 non-stackable Hubs can
be cascaded at most. Switch doesn't have the
limitation |
|
|
|
| Q28
What
is a USB Hub? |
|
| USB
hub typically consists of a single upstream
port (designed to connect directly to your
computer or to another hub) and multiple downstream
ports. |
|
| Q29How
Many USB Hubs can I connect together? |
|
| In
total you should only connect
5 tiers of USB hubs together.
A tier is defined by the number
of hubs; a device's signal must
pass through before it reaches
the host. For example, using a
4-port USB hub, you could connect
a theoretical maximum of 341 hubs
in five tiers; this would leave
you with an incredible 1024 ports
to connect USB devices! But you
should only connect 127 devices
together at any time. |
|
|
| Q30 Which
Operating System do I need to
use the USB Hub? |
|
| You
will need Windows 95 OSR 2.1 with
USB support, Windows 98, Windows
NT 5.0, or MacOS 8.1.. |
|
|
|
|
|
| Q31 What
software is needed to get the USB Hub to work? |
|
| No software
is required as long as your computer can support
USB Devices. |
|
|
|
| Q32 But
I have Windows 98 running on my system. When
I plug in the Hub, I am asked for a driver.
Where can I locate the driver for this device? |
|
•
Some brand name computers such as Dell or
Compaq may not fully install USB Hardware
List drivers.
• To fix this you
will have to extract the usb.inf
file from the precopy2.cab
file on the Windows 98 CD under the win98
directory.
• From Windows Explorer,
open the win98 Directory and double click
on the precopy2.cab file.
• Search
for the usb.inf file and copy into you c:\windows\inf
directory.
• The next time Windows
detects the HUB, click on Have
Disk. Choose the c:\windows\inf directory
and click OK.
• Choose Generic
USB Hub. |
|
|
|
| Q33 Which
Operating System do I need to use the USB
Hub? |
|
The
power supply is not needed if using low speed
devices (1.5 Mbps) such as joysticks, mice
and keyboards.
For full speed devices (12 Mbps) you must
have the USB Hub in Self-powered mode. The
USB Hub is a full speed device, so if you
are connecting another USB Hub, you must use
a power supply with the USB Hub you are connecting
to.
If you are using the 7-Port USB Hub, you must
attach the power supply to access the 3 side
ports. |
|
|
|
| Q34 For
Fast Ethernet Hubs, could Class I repeaters
be cascaded like Class II? |
|
| The
answer is no. Class I and Class II Hubs are
defined in IEEE 802.3u Fast Ethernet specifications.
The most basic difference between them is
that Class I repeaters cannot be cascaded,
but Class II repeated can be cascaded two
units deep. Class I means one Hub per collision
domain unless the devices are stackable or
interconnect via a switch or a bridge/router. |
|
|
|
| Q35 Will
there be any problems after changing the 10/100
Network Adapter to full duplex mode? |
|
| Your
computer won¡¦t work if you do this change!
Base on IEEE standard, Hubs can only perform
under half duplex mode, only a Switch can
support Full duplex. |
|
|
|
| Q36 Could
I improve the network speed? It seems slower
when more users are connected to the Hub. |
|
| Since
Hubs are shared devices, you can¡¦t improve
the speed. As more users are connected to
the Hub, the total bandwidth will decrease. |
|
|
|
| Q37 Help!
My Hub doesn't connect to the network! |
|
Here¡¦re
some important troubleshooting tips for you:
¡E Check the Link/Activity LED on the Hub.
If the Link/Activity LED isn't lit, check
all connections at the adapter and the Hub.
Make sure the adapter drivers are loaded.
¡E Try another port on the Hub.
¡E Make sure the cable is installed properly.
The network cable must be securely attached
at all connections. If the cable is attached
but the problem persists, try a different
cable.
¡E Restart the Hub. Turn off the power. After
a while, turn on power again. |
|
|
|
