1. Lecture #15: High speed LANs
C o n t e n t s
Fast LANs
FDDI
Fast Ethernet
HIPPI 2 3 7 8

2. Fast LANs Advances in transmission speed and distance. Technology FDDI
Fast Ethernet
Application
inter-LAN backbones
when 100 Mb/S and upper bandwidth is needed
Inter LAN backbone
e.g. FDDI Ring
...
ATM
ETHERNET
TOKEN
RING
FIBER
CHANNEL
FDDI B
Bridge

3. FDDI FDDI (Fiber Distributed Data Interface)
token ring topology (because of the media)
standard bandwidth 100 Mb/S
ring length up to 200 km
application
inter LAN backbones
PCM trunks and ISDN traffic (FDDI-II)
FDDI physical implementation
multimode fibers (thicker, based on the internal reflection, slower but cheaper than thin single-mode fibers)
LED as light sources
BER under (Bit Error Rate).

4. FDDI Topology: FDDI Station classes - A/B 4-out-of-5 bit coding -
doubled ring for full duplex transmission or
single ring with token circulation
FDDI Station classes - A/B
4-out-of-5 bit coding -
each { } is coded with 5 bits –
75% more congested coding than Manchester code but not self-clocked  synchronization by leading preamble for each frame.
4-bit data sequence (16)
frame delimiters (3)
control sequences (2)
hardware signals (3)

5. FDDI Token Ring and Frame
Much longer circumnavigate distances than in allow multiple frame circulation in the ring
One-token-multiple-frames scheme (asynchronous “bursty” traffic)
General Frame format
preamble
Start/End Delimiters (SD/ED)
Frame Control byte (FC) /Data/control frame/
Destination and Source Addresses - 2 or 6 bytes (DA, SA)
unlimited Info
FCS - CRC error control
Frame Status byte (FS)
Token Frame format
Frame Control byte (FC)
15/1
15/2

6. FDDI Token Ring Timing and Synchronous Transmission
Token holding timer - station time limit for token holding
Token rotation timer - starting the token recovery procedure after the time-out
Valid transmission timer - detecting transient ring problems after the time-out
Synchronous transmission over FDDI (“stream traffic”):
synchronous frame
header field (16B) for non-circuit-switching data
data field (up to 96B) - 4 T1 (4x24) PCM channels of 1.544Mb/S or 3 E1 (3x32) CCITT channels of Mb/S.
timing - up to 16 sync. frames per 125mS period i.e. up to 8000*16 sync. frames/S (synchronous transmission bandwidth 8000*16*96B*8b= b/S)

7. Fast ETHERNET
Faster Ethernet MAC protocol over 10 times shorter transmission cable
ETH cable segments are connected by hubs
Cabling
cat. 3 twisted pair - 4 twisted pairs: to/from hub + 2 pairs switchable to the active station
cat. 5 twisted pair - 2 twisted pairs: to/from hub
fiber - in and out multimode fiber up to 2 km
Twisted pair hubs
shared hub
switched (buffered) hub
4/47

8. HIPPI Standard 4/48 HIPPI (High Performance Parallel Interface) . . .
Point-to-Point parallel computer interface with Primary/Secondary logical connectivity
crossbar switch extension
cabling: 50 twisted pair lines in parallel splitting 32b/18b (data/interface control incl. 1 parity bit) simplex mode; two lines in parallel for full duplex mode; maximum line length 25m.
Frame format: 256 words (32b) with parity bit per each word and and a parity word at the end of each frame (no CRC):
4/48 30 . 1 31
bFF
bFE b1 b0
. . .
p30 p1 p0
p31 pb