1

Lecture #15: High Lecture #15: High speed LANsspeed LANs

C o n t e n t s C o n t e n t s

Fast LANsFast LANs

FDDIFDDI

Fast EthernetFast Ethernet

HIPPIHIPPI

3

2

7

8

2

Fast LANsFast LANs

Inter LAN backbone e.g. FDDI Ring

...

ATM

ETHERNET

TOKENRING

FIBERCHANNEL

FDDI

ETHERNET

TOKENRING

FIBERCHANNEL

...

ATM

FDDI

BB

B

BBB

B

B

B Bridge

Advances in transmission speed and distance.Technology

FDDIFast Ethernet

Applicationinter-LAN backboneswhen 100 Mb/S and upper bandwidth is needed

3

FDDI FDDI FDDIFDDI (Fiber Distributed Data Interface) (Fiber Distributed Data Interface)

– token ring topology (because of the media)token ring topology (because of the media)– standard bandwidth 100 Mb/Sstandard bandwidth 100 Mb/S– ring length up to 200 kmring length up to 200 km– application application

• inter LAN backbonesinter LAN backbones• PCM trunks and ISDN traffic (FDDI-II)PCM trunks and ISDN traffic (FDDI-II)

FDDI physical implementationFDDI physical implementation– multimode fibers (thicker, based on the multimode fibers (thicker, based on the

internal reflection, slower but cheaper than internal reflection, slower but cheaper than thin single-mode fibers)thin single-mode fibers)

– LED as light sourcesLED as light sources– BER under 10BER under 10-10 -10 ((Bit Error RateBit Error Rate). ).

4

FDDIFDDI TopologyTopology::

– doubled ring for full duplex transmission or doubled ring for full duplex transmission or

– single ring with token circulationsingle ring with token circulation

FDDI Station FDDI Station classesclasses - A/B - A/B 4-out-of-5 bit 4-out-of-5 bit codingcoding - -

each each {{ }} is coded with is coded with 5 bits –5 bits –

75% more congested coding than Manchester 75% more congested coding than Manchester code but not self-clocked code but not self-clocked synchronization by synchronization by leading preamble for each frame.leading preamble for each frame.

4-bit data sequence (16)frame delimiters (3)control sequences (2)hardware signals (3)

5

FDDI Token Ring and FDDI Token Ring and FrameFrame

Much longer circumnavigate distances than in Much longer circumnavigate distances than in 802.5 allow multiple frame circulation in the ring802.5 allow multiple frame circulation in the ring

One-token-multiple-frames scheme One-token-multiple-frames scheme (asynchronous “bursty” traffic) (asynchronous “bursty” traffic)

General Frame formatGeneral Frame format– preamble preamble – Start/End Delimiters (SD/ED)Start/End Delimiters (SD/ED)– Frame Control byte (FC) /Data/control frame/Frame Control byte (FC) /Data/control frame/– Destination and Source Addresses - 2 or 6 bytes (DA, Destination and Source Addresses - 2 or 6 bytes (DA,

SA)SA)– unlimited Infounlimited Info– FCS - CRC error controlFCS - CRC error control– Frame Status byte (FS) Frame Status byte (FS)

Token Frame formatToken Frame format– preamblepreamble– Frame Control byte (FC)Frame Control byte (FC)– Frame Status byte (FS)Frame Status byte (FS)

15/1

15/2

6

FDDI Token Ring Timing and FDDI Token Ring Timing and Synchronous TransmissionSynchronous Transmission

FDDI token ring timing:FDDI token ring timing:– Token holding timer - station time limit for token holdingToken holding timer - station time limit for token holding– Token rotation timer - starting the token recovery procedure Token rotation timer - starting the token recovery procedure

after the time-outafter the time-out– Valid transmission timer - detecting transient ring problems Valid transmission timer - detecting transient ring problems

after the time-outafter the time-out Synchronous transmission over FDDI (“stream traffic”):Synchronous transmission over FDDI (“stream traffic”):

– synchronous frame synchronous frame • header field (16B) for non-circuit-switching data header field (16B) for non-circuit-switching data • data field (up to 96B) - 4 T1 (4x24) PCM channels of data field (up to 96B) - 4 T1 (4x24) PCM channels of

1.544Mb/S or 3 E1 (3x32) CCITT channels of 2.048 Mb/S.1.544Mb/S or 3 E1 (3x32) CCITT channels of 2.048 Mb/S.

– timing - up to 16 sync. frames per 125timing - up to 16 sync. frames per 125S period i.e. S period i.e. up to 8000*16 sync. frames/S (synchronous up to 8000*16 sync. frames/S (synchronous transmission bandwidth 8000*16*96B*8b=98.304 transmission bandwidth 8000*16*96B*8b=98.304 b/S)b/S)

7

Faster Ethernet MAC protocol over 10 Faster Ethernet MAC protocol over 10 times shorter transmission cabletimes shorter transmission cable

ETH cable segments are connected by ETH cable segments are connected by hubshubs

CablingCabling– cat. 3 twisted pair - 4 twisted pairs: to/from cat. 3 twisted pair - 4 twisted pairs: to/from

hub + 2 pairs switchable to the active station hub + 2 pairs switchable to the active station – cat. 5 twisted pair - 2 twisted pairs: to/from cat. 5 twisted pair - 2 twisted pairs: to/from

hub hub – fiber - in and out multimode fiber up to 2 kmfiber - in and out multimode fiber up to 2 km

Twisted pair hubsTwisted pair hubs– shared hub shared hub – switched (buffered) hubswitched (buffered) hub

Fast ETHERNETFast ETHERNET

4/47

8

HIPPIHIPPI (High Performance Parallel Interface) (High Performance Parallel Interface)– Point-to-Point parallel computer interface with Point-to-Point parallel computer interface with

Primary/Secondary logical connectivity Primary/Secondary logical connectivity

– crossbar switch extension crossbar switch extension

– cabling: 50 twisted pair lines in parallel splitting 32b/18b cabling: 50 twisted pair lines in parallel splitting 32b/18b

(data/interface control incl. 1 parity bit) simplex mode; (data/interface control incl. 1 parity bit) simplex mode;

two lines in parallel for full duplex mode; maximum line two lines in parallel for full duplex mode; maximum line

length 25m.length 25m.

– Frame format: 256 words (32b) with Frame format: 256 words (32b) with parity bitparity bit per each per each

word and and a word and and a parity wordparity word at the end of each frame (no at the end of each frame (no

CRC):CRC):

HIPPI StandardHIPPI Standard

4/48

30 ...

10

31bFF

30 ...

10

31bFE

30 ...

10

31b1

30 ...

10

31b0

. . .p30

...

p1

p0

p31

pb

9

10

11

12