Transcript S7C2 – Legacy Ethernet

S7C2 – Legacy Ethernet
From the Old to the New
Legacy Ethernet Characteristics
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CSMA/CD
Shared Bandwidth
10 Mbps
Common Broadcast
Physical Star Topology; logical bus
Broadcasts
• Ethernet characteristic
• Routers use to announce routing tables
• ARP request
To Increase Bandwidth
• Upgrade the user to 10BASE-T full duplex
and immediately double the bandwidth.
• Upgrade the user to 100BASE-X half
duplex.
• Upgrade the user to 100BASE-X full
duplex
Frame Transmission
• Unicast
– One source to one destination
• Multicast
– Single data stream from one source to multiple
clients
• Saves bandwidth and controls network traffic
• Broadcast
– Single data stream to all hosts on the subnet
Multicast
• Cisco has a special multicast address
reserved, 01-00-0C-CC-CC-CC, which
enables Cisco devices to transmit to all
other Cisco devices on the segment.
• The reserved multicast OSPF IP addresses
224.0.0.5 and 224.0.0.6 translates to MAC
multicast addresses of 01-00-5E-00-00-05
and 01-00-5E-00-00-06.
LAN FRAMES
• Layer 2 Header – 14 octets
– MAC DA 6 octets
– MAC SA 6 octets
– Type (Ev2) or length (802.3/802.2) 2 octets
• Layer 2 Data field – 1500 octets
– V2 and 802.3 data
– 802.2 DSAP, SSAP, Control, Data
Duplex
• Half-Duplex
– Transmit and Receive wires
– Relies on Collision Detection
• Full-Duplex
– No loopback
– No collision detection
– Full duplex ethernet controller
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Transmit circuit connects directly to receive circuit
No collisions
Significant performance improvement (almost 100%)
Eliminates contention for line
Uses single port for each full-duplex connection
Media Comparisons
Standard CabType Mode
Pairs
Dis-Met
10B-T
Half
2
100
100B-TX 5
H &F
2
100
100B-T4 3
H
4
100
100B-T2 3,4,5
H and F
2
100
100B-FX Multi
H and F
1
412(H)
2000(F)
10 KM
3,4,5
Single