256744
Descrição
Mapa Mental por jce299792458, atualizado more than 1 year ago
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Criado por jce299792458
aproximadamente 11 anos atrás
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Building Ethernet LANs with Switches
- HUB
- When receive an
electrical signal in one
port,repeats the signal
out all other ports
- When two or more
devices send at the same
time, an electrical collision
occurs, making both
signals corrupt
- devices must take
turns by using carrier
sense multiple access
with collision
detection (CSMA/CD)
logic
- When receive an
electrical signal in one
port,repeats the signal
out all other ports
- Bridge
- Separated devices
into groups called
collision domains.
- Reduced the number of collisions that
occurred in the network, because
frames inside one collision domain did
not collide with frames in another
collision domain.
- Increased bandwidth by
giving each collision
domain its own separate
bandwidth, with one
sender at a time per
collision domain.
- Buffer or queue the
frame until the outgoing
interface can send the
frame
- Separated devices
into groups called
collision domains.
- Switches
- Like bridges, switches segment a
LAN into separate collision domains,
each with its own capacity
- Switching Logic
- Deciding when to forward a frame or when to filter (not
forward) a frame, based on the destination MAC
address
- Learning MAC addresses by examining
the source MAC address of each frame
received by the switch.
- Creating a (Layer 2) loop-free
environment with other bridges by using
Spanning Tree Protocol (STP)
- Deciding when to forward a frame or when to filter (not
forward) a frame, based on the destination MAC
address
- Switching Logic
- How Switches
Learn MAC
Addresses
- Listening to incoming
frames and examining
the source MAC addres
in the frame.
- Flooding Frames
- When there is no matching entry in the table,
switches forward the frame out all interfaces
(except the incoming interface)
- When there is no matching entry in the table,
switches forward the frame out all interfaces
(except the incoming interface)
- Flooding Frames
- Inactivity timer
- Listening to incoming
frames and examining
the source MAC addres
in the frame.
- Avoiding Loops
Using Spanning
Tree Protocol
- Without STP, any flooded frames would
loop for an indefinite period of time in
Ethernet networks with physically redundant
links
- Blocks some ports from forwarding
frames so that only one active path
exists between any pair of LAN
segments.
- Blocks some ports from forwarding
frames so that only one active path
exists between any pair of LAN
segments.
- Without STP, any flooded frames would
loop for an indefinite period of time in
Ethernet networks with physically redundant
links
- Switch Internal Processing
- Switching Method
- Fragment-free
- The switch forwards the frame after receiving the first 64
bytes of the frame, thereby avoiding forwarding frames
that were errored because of a collision.
- The switch forwards the frame after receiving the first 64
bytes of the frame, thereby avoiding forwarding frames
that were errored because of a collision.
- Cut-through
- The switch forwards the frame as soon as it can.
This reduces latency but does not allow the switch
to discard frames that fail the FCS check.
- The switch forwards the frame as soon as it can.
This reduces latency but does not allow the switch
to discard frames that fail the FCS check.
- Store-and-forward
- The switch fully receives all bits in the frame
(store) before forwarding the frame (forward). This
allows the switch to check the FCS before
forwarding the frame.
- The switch fully receives all bits in the frame
(store) before forwarding the frame (forward). This
allows the switch to check the FCS before
forwarding the frame.
- Fragment-free
- Switching Method
- Like bridges, switches segment a
LAN into separate collision domains,
each with its own capacity
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