10-Mbps Ethernet10-Mbps Ethernet
• Legacy Ethernet– 10BASE5, 10BASE2, and 10BASE-T
• Four common features of Legacy Ethernet – Timing parameters– Frame format– Transmission process– Basic design rule
10-Mbps Ethernet10-Mbps Ethernet10BASE5
Single thick coaxial cable bus Cable is large and heavy
Primary benefit was length (500m) Only in half-duplex
Inexpensive Sensitive to signal reflection
No configuration Not for new installations
Components are difficult to find Difficult to install
10-Mbps Ethernet10-Mbps Ethernet10BASE2
Uses half-duplex Compared to 10Base5
Components are difficult to find Low cost
No need for hubs Smaller size, lighter weight
Not for new installationsGreater flexibility
Thin netInstallation easier
10-Mbps Ethernet10-Mbps Ethernet10BASE-T
Cheaper and easier to install Extended Star
Category 3 Originally half-duplex protocol
Category 5 Full-duplex features added later
Category 5e New installations Cat5e or better
Uses a hub10 Mbps in half-duplex mode
Star topology 20 Mbps in full-duplex mode
Wiring and ArchitectureWiring and Architecture
• 5-4-3 rule– No more than five segments – Separated by no more than four repeaters.
– No more than three populated segments between any two
distant stations
• Hubs or repeaters merely extend the length of a network segment within a single collision domain
• Bridges and switches divide a segment into separate collision domains
Manchester Encoding
• Manchester encoding is used in 10 Mbps systems • The direction of the edge transition in the middle of the timing
window determines the binary value
100-Mbps Ethernet
• 100-Mbps Ethernet is also known as Fast Ethernet– 100BASE-TX is copper UTP
– 100BASE-FX is multimode optical fiber
• Three common characteristics:– Timing parameters
– Frame format
– Parts of the transmission process
100-Mbps Ethernet
• Timing parameters– One bit time in 100-Mbps Ethernet is 10nsec
• Frame format– 100-Mbps frame format is the same as the 10-
Mbps frame
• Parts of the transmission process– Two separate encoding steps are used
• The first part of the encoding uses a technique called 4B/5B
• The second part of the encoding is the actual line encoding specific to copper or fiber
100-Mbps Ethernet
• 100BASE-TX uses 4B/5B encoding which is then scrambled • Converted to multi-level transmit-3 levels or MLT-3.• Half-duplex = 100 Mbps • Full-duplex = 200 Mbps
Fast Ethernet Architecture
• Fast Ethernet links consist of a connection between a station and a hub or switch
– Hubs are considered multi-port repeaters
– Switches are considered multi-port bridges
– These are subject to the 100 m UTP distance limitation
Fast Ethernet Architecture
• Class I repeater – Any repeater that changes between one Ethernet
implementation and another
– 140 bit-times of latency
• Class II repeater
– 92 bit-times latency
– Cable between Class II repeaters may not exceed 5 meters
Fast Ethernet Architecture
• Signaling scheme is inherently full duplex– Half duplex are not uncommon – Half duplex is undesirable
• Switches have made the 100m limitation less important
• Workstations are located within 100m of the switch
• 100 m distance starts over at the switch
1000-Mbps Ethernet
• 1000-Mbps Ethernet or Gigabit Ethernet Transmission – Fiber and copper media
• The 1000BASE-X IEEE 802.3z– Specifies 1 Gbps full duplex over optical fiber
• 1000BASE-TX, 1000BASE-SX, and 1000BASE-LX
– Timing parameters• 1 nanosecond or 1 billionth of a second bit time.
– Frame Format • Same format used for 10 and 100-Mbps Ethernet
– Transmission • Depending on the implementation
1000-Mbps Ethernet
• 1000BASE-T (IEEE 802.3ab) was developed to provide additional bandwidth for:
– Intra-building backbones– Inter-switch links– Server farms– Connections for high-end workstations – Supports both half-duplex and full-duplex
• Fiber-based Gigabit Ethernet (1000BASE-X)
– Uses 8B/10B encoding (similar to 4B/5B) – This is followed by Non-Return to Zero (NRZ) line encoding
1000Base-LX/SX• Common to all versions of 1000 Mbps
– Timing– Frame format– Transmission
• NRZ signals are pulsed into the fiber– Short-wavelength (1000BASE-SX )– Long-wavelength (1000BASE-LX)
• Media Access Control – Link as point-to-point
• Separate fibers – Transmitting (Tx) – Receiving (Rx) – Inherently full duplex
Gigabit Ethernet
• Gigabit Ethernet is the dominant technology for:
– Backbone installations,
– High-speed cross-connects
– General infrastructure
10 Gigabit Ethernet• IEEE 802.3ae, governs the 10GbE family
• Provide increased bandwidth
• Interoperable with existing infrastructure
• Implementations being considered:
– 10GBASE-SR
– 10GBASE-LX4
– 10GBASE-LR and 10GBASE-ER
– 10GBASE-SW, 10GBASE-LW, and 10GBASE-EW
10 Gigabit Ethernet• 10GBASE-SR –
– short distances, supports a range between 26 m to 82 m
• 10GBASE-LX4 – – Uses wide wavelength division multiplexing (WWDM)– 240 m to 300 m over multimode fiber – 10 km over single-mode fiber
• 10GBASE-LR and 10GBASE-ER – – Support 10 km and 40 km over single-mode fiber
• 10GBASE-SW, 10GBASE-LW, and 10GBASE-EW – – Known collectively as 10GBASE-W – Works with OC-192 synchronous transport module
Future of EthernetFuture of Ethernet• The future of networking media is three-fold:
1. Copper (up to 1000 Mbps, perhaps more) 2. Wireless (approaching 100 Mbps, perhaps more)
3. Optical fiber (currently at 10,000 Mbps and soon to be more)
• Copper and wireless media have certain physical and practical limitations
• Limitations on optical fiber are:
– Electronics technology • emitters and detectors
– Fiber manufacturing processes
• Developments in Ethernet – Heavily weighted towards Laser light sources– Single-mode optical fiber