Ethernet Technology
Ethernet Technology
Ethernet Technology
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General Model of a Switch<br />
Crossbar - An Example of switching Fabric<br />
Control<br />
Subsystem(s)<br />
N x N<br />
<br />
N ports<br />
FE Switch<br />
inbound<br />
1 IPC<br />
OPC<br />
1<br />
N<br />
. . .<br />
IPC<br />
Switching Fabric<br />
. . .<br />
OPC<br />
- Layer 2 device (operated at frame-basis, forwarding based on the MAC address)<br />
- Exchange information based upon MAC address (learned & stored internally)<br />
- Example: a 16x16 switch or a 16-Port switch<br />
- Three operation modes: (viewpoints: latency, error forwarding, buffers, etc)<br />
Store-and-forward switching, Cut-through switching, and<br />
modified/Runt-free/Interim cut-through switching<br />
outbound<br />
<strong>Ethernet</strong> <strong>Technology</strong> 53<br />
N<br />
inputs<br />
1<br />
2<br />
. . .<br />
N<br />
Input<br />
queues<br />
(Buffer)<br />
1<br />
2<br />
. . .<br />
N<br />
output<br />
. . .<br />
1 2 . . . N<br />
1 2 . . . N<br />
outputs<br />
Arbiter<br />
Output conflict<br />
Buffer/Memory<br />
Blocking<br />
(Nonblocking or<br />
Rearrangeable<br />
Switch)<br />
(An illustration)<br />
<strong>Ethernet</strong> <strong>Technology</strong> 54<br />
Hub () versus Switch ()<br />
Switch’s Basic Operation<br />
• Layer-1 device (hub)<br />
• Multiple repeater<br />
• TX/RX ONE pair at a time<br />
• Connect multiple <strong>Ethernet</strong><br />
segments into ONE network<br />
(1 collision domain as a whole)<br />
• Collision domain in hubed ntwks<br />
• Layer-2 device (switch)<br />
• Multiport bridge<br />
• TX/RX Multiple pairs at a time<br />
• Multiple <strong>Ethernet</strong> segments operate<br />
separately but reachable<br />
(1 collision domain per port)<br />
• Broadcast domain in switched ntwks<br />
Learning<br />
Forwarding<br />
MAC address table (basic) :<br />
MAC address<br />
Port number<br />
0080c8-234568 2<br />
Broadcast<br />
domain<br />
--<br />
<strong>Ethernet</strong> <strong>Technology</strong> 55<br />
-- <strong>Ethernet</strong> <strong>Technology</strong> A switched network = a broadcast domain.<br />
56
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