User`s guide

Signamax 065-7931 16-Port 10/100/1000BaseT/TX WebSmart Switch
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The maximum length of the extension is equal to the quantity (slotTime -
minFrameSize). The MAC continues to monitor the medium for collisions while it is
transmitting extension bits, and it will treat any collision that occurs after the
threshold (slotTime) as a late collision.
3-4. How does a switch work?
The 065-7931 Gigabit WebSmart switch is a layer 2 Ethernet Switch
equipped with 16 10/100/1000 Mbps Twisted Pair (TP) ports and 2 Gigabit dual
media TP/SFP (Small Form-factor Pluggable) fiber ports . Each port on it is an
independent LAN segment and thus has 16 LAN segments and 16 collision
domains, in contrast to the traditional shared Ethernet hub in which all ports share
the same media and use the same collision domain and thus limit the bandwidth
utilization. With the switch’s separated collision domains, it can extend the LAN
diameter farther than a shared hub does and highly improve the efficiency of the
traffic’s transmission.
Due to this architecture, the switch can provide full-duplex operation to
double the bandwidth per port and provide many other features, such as VLAN,
bandwidth aggregation and so on, that are not able to be supported in a shared hub.
Terminology
Separate Access Domains:
As described in the section of “What’s Ethernet?”, Ethernet utilizes
CSMA/CD to arbitrate who can transmit data to the station(s) attached in the LAN.
When more than one station transmits data within the same slot time, the signals
will collide, referred to as collision. The arbitrator will arbitrate who should gain the
media. The arbitrator is a distributed mechanism in which all stations contend to
gain the media. Please refer to the “What’s Ethernet?” section for more details.
In Fig.3-5, assumed as half duplex, you will see some ports of the switch are
linked to a shared hub, which connects many hosts, and some ports just are
individually linked to a single host. The hosts attached to a shared hub will be in the
same collision domain, separated by the switch, and use CSMA/CD rule. For the
host directly attached to the switch, because no other host(s) joins the traffic
contention, hence it will not be affected by CSMA/CD. These LAN segments are
separated in different access domains by the switch.
Micro-segmentation:
To have a port of the switch connected to a single host is referred to as
micro-segmentation. It has the following interesting characteristics.
- There is no need for the access contention (e.g.Collision). They
have their own access domain. But, collision still could happen
between the host and the switch port.
- When performing in the full duplex mode, the collision vanishes.
- The host owns a dedicated bandwidth of the port.
The switch port can run at different speeds, such as 10 Mbps, 100 Mbps or
1000 Mbps. A shared hub cannot offer this capability.