Ethernet Fast and Gigabit Ethernet
Networks: Fast Ethernet
1
Fast Ethernet (100BASE-T)
How to achieve 100 Mbps capacity?
LLC MAC Convergence Sublayer Data Link Layer Physical Layer
MII
Media Independent Interface Media Dependent Sublayer
Media Independent Interface provides three choices.
Networks: Fast Ethernet 2
Fast Ethernet [IEEE 802.3u]
Figure 4-21.The original fast Ethernet cabling. * Concept facilitated by 10Mbps/100Mbps Adapter
Cards
Networks: Fast Ethernet 3
100 BASE T
Networks: Fast Ethernet
4
Fast Ethernet Details
UTP Cable has a 30 MHz limit
Not feasible to use clock encoding (i.e., NO Manchester encoding)
Instead use bit encoding schemes with sufficient transitions for receiver to maintain clock synchronization.
Networks: Fast Ethernet
5
100 BASE T4
Can use four separate twisted pairs of Cat 3 UTP Utilize three pair in both directions (at 33 1/3 Mbps) with other pair for carrier sense/collision detection. Three-level ternary code is used 8B/6T. Prior to transmission each set of 8 bits is converted into 6 ternary symbols.
Networks: Fast Ethernet 6
100 BASE T4
The signaling rate becomes
100 x 6/8 ------------ = 25 MHz 3 Three signal levels : +V, 0, -V Codewords are selected such that line is d.c.balanced all codewords have a combined weight of 0 or 1.
Networks: Fast Ethernet 7
100 BASE T4
Ethernet Interframe gap = 9.6 microseconds becomes 960 nanoseconds. 100 m. station to hub; 200 meters between stations Maximum of two Class II repeaters.
Networks: Fast Ethernet
8
100 Base TX
Uses two pair of twisted pair, one pair for transmission and one pair for reception. Uses either STP or Cat 5 UTP. Uses MTL-3 signaling scheme that involves three voltages. Uses 4B/5B encoding. There is a guaranteed signal transition at least every two bits.
Networks: Fast Ethernet 9
100 BASE FX
Uses two optical fibers, one for transmission and one for reception. Uses FDDI technology of converting 4B/5B to NRZI code group streams into optical signals.
Networks: Fast Ethernet
10
Fast Ethernet Repeaters and Switches
Class I Repeater supports unlike physical media segments (only one per collision domain) Class II Repeater limited to single physical media type (there may be two repeaters per collision domain) Switches to improve performance can add fullduplex and have autonegotiation for speed mismatches .
Networks: Fast Ethernet 11
Collision Domains
Networks: Fast Ethernet
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Networks: Fast Ethernet
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Networks: Fast Ethernet
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Gigabit Ethernet History
In February 1997 the Gigabit Ethernet Alliance announced that IEEE802.3z Task Force met to review the first draft of the Gigabit Ethernet Standard According to IDC by the end of 1997 85% of all network connections used Ethernet. Higher capacity Ethernet was appealing because network managers can leverage their investment in staff skills and training 1000 BASE X (IEEE802.3z) was ratified in June 1998.
Networks: Fast Ethernet 15
Gigabit Ethernet (1000 BASE X)
Provides speeds of 1000 Mbps (i.e., one billion bits per second capacity) for half-duplex and full-duplex operation. Uses Ethernet frame format and MAC technology
CSMA/CD access method with support for one repeater per collision domain Backward compatible with 10 BASE-T and 100 BASE-T
Uses 802.3 full-duplex Ethernet technology. Uses 802.3x flow control. All Gigabit Ethernet configurations are point-to-point!
Networks: Fast Ethernet 16
Networks: Fast Ethernet
17
Gigabit Ethernet Technology
Figure 4-23.Gigabit Ethernet cabling.
1000 BASE SX fiber - short wavelength 1000 BASE LX fiber - long wavelength 1000 BASE CX copper - shielded twisted pair 1000 BASE T copper - unshielded twisted pair * Based on Fiber Channel physical signaling technology.
Networks: Fast Ethernet 18
Gigabit Ethernet BASE-T)
LLC (1000 MAC Data Link Layer
GMII
Gigabit Media Independent Interface Physical Layer Media Dependent Interface Medium
Networks: Fast Ethernet
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Gigabit Media Independent Interface
GMII
Allows any physical layer to be used with a given MAC. Namely, Fiber Channel physical layer can be used with CSMA/CD Permits both full-duplex and half-duplex.
Networks: Fast Ethernet
20
1000 BASE SX
Short wavelength Supports duplex links up to 275 meters. 770-860 nm range; 850 nm laser wavelength (FC) Fiber Channel technology PCS (Physical Code Sublayer) includes 8B/ 10B encoding with 1.25 Gbps line. Only multimode fiber Cheaper than LX.
Networks: Fast Ethernet 21
8B/10B Encoder
Networks: Fast Ethernet
22
8B/10B Encoding Issues
When the encoder has a choice for codewords, it always chooses the codeword that moves in the direction of balancing the number of 0s and 1s. This keeps the DC component of the signal as low as possible.
Networks: Fast Ethernet 23
1000 BASE LX
Long wavelength Supports duplex links up to 550 meters. 1270-1355 nm range; 1300 nm wavelength using lasers. Fiber Channel technology PCS (Physical Code Sublayer) includes 8B/10B encoding with 1.25 Gbps line. Either single mode or multimode fiber.
Networks: Fast Ethernet 24
1000 BASE CX
`Short haul' copper jumpers Shielded twisted pair. 25 meters or less typically within wiring closet. PCS (Physical Code Sublayer) includes 8B/ 10B encoding with 1.25 Gbps line. Each link is composed of a separate shielded twisted pair running in each direction.
Networks: Fast Ethernet 25
1000 BASE T
Twisted Pair
Four pairs of Category 5 UTP. IEEE 802.3ab ratified in June 1999. Category 5, 6 and 7 copper up to 100 meters. This requires extensive signal processing.
Networks: Fast Ethernet
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Gigabit Ethernet compared to Fiber Channel
Since Fiber Channel (FC) already existed, the idea was to immediately leverage physical layer of FC into Gigabit Ethernet. The difference is that fiber channel was viewed as specialized for high-speed I/O lines. Gigabit Ethernet is general purpose and can be used as a high-capacity switch.
Networks: Fast Ethernet 27
Gigabit Ethernet
Viewed as LAN solution while ATM is WAN solution. Gigabit Ethernet can be shared (hub) or swit...