Transcript Protocols animated (ppt) [renamed]

Ethernet (Medium Access Control Protocol)
A
B
C
D
 A single shared comm. Line
 Used by all (each check if “free” or “busy”)
 Message is broadcasted to all
 Message has
 “destination address” and “message-body”
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© Leong Hon Wai, 2003-2008
(UIT2201: Networks) Page 1
Ethernet Protocol (how it works)
A
B
C
D
My message!!
Process it…
D
message
Not mine.
Discard it…
 Node A wants to send something to node D
 Message’s “destination address” = D
 Message is broadcasted to all…
 Every Machine checks
 If not mine, then discard; else process message;
LeongHW, SoC, NUS
© Leong Hon Wai, 2003-2008
(UIT2201: Networks) Page 2
Ethernet Protocol (Collision)
A
B
C
D
 What if shared line is busy when node B wants to send?
 Eg: If node A is currently sending….
 Node B waits… and send after node A is done.
 What if many nodes are waiting…
 And simultaneously send when node A is done!
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© Leong Hon Wai, 2003-2008
(UIT2201: Networks) Page 3
LAN
How to Resolve
Collisions !!
 Length of collision delay
is randomly generated.
 So, different delays for
different waiting nodes….
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(UIT2201: Networks) Page 4
LAN (MACP – details from text)
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LAN (MACP – details from text)
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LAN (MACP)
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WAN Network….
 Paths from B to F?
 What if node C is faulty?
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(UIT2201: Networks) Page 8
WAN
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(UIT2201: Networks) Page 9
WAN
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(UIT2201: Networks) Page 10