Fiziska Limena Tehnologijas

1
Fiziska Limena Tehnologijas

• Guntis Barzdinš
• Datortikli 1

2
Fiziska limena standarti

• Sinhrona un asinhrona parraide (V.35, RS-232)
• Telefonu tikla interfeisi
• Analogais (datu parraide vajadzigs modems, RS-232
  tipiski)
• ISDN BRI,
• E1, E2, E3 (lieto ar ISDN PRI, SS7, V.35, G.703)
• SDH STM-1 (155Mb/s) STM-48 (9.6Gb/s)
• ATM jeb B-ISDN neveiksmigs pretstats SDH
• Ethernet reals konkurents SDH (10Mb/s, 100Mb/s,
  1Gb/s, 10Gb/s)
• Eksotiskie DSL, kabelu TV, bezvadu (radio)

3
DTE un DCE interfeisi

• Savieno tikai DCE un DTE interfeisus dažadi
  štepseli un funkcijas
• DCE-DCE vai DTE-DTE tieši nevar savienot vajag
  Null-modem iekartu (kabeli)
• Sinhrona parraide DCE ir sinhronizacijas
  (pulkstena) avots

Data Terminal Equipment End of the user's
device on the WAN link
Data Circuit-Terminating Equipment End of the
WAN provider's side of the communication facility
Modem
Terminal
DCE
DTE
4
Izdalita WAN sakaru linija
E1 vai SDH
V.35
V.35
64Kb/s 2Mb/s
5
Sinhrona un asinhrona datu parraide

• Nebalansets interfeiss mazi atrumi
• Balansets interfeiss lieli atrumi
• Lai gan tas nav obligati, tradicionali
• Asinhrona parraide nebalansets interfeiss
• Sinhrona parraide balansets interfeiss

6
Nebalansets interfeiss
Signal gt 3v 0 Signal lt -3v 1
Kopiga zeme daudziem signaliem!
RS232 Pinout on DB9
RS-232, RS-232C, RS-232D, V.24, V.28, V.10 Max
atrums 19.2Kb/s (standarts), 56Kb/s (strada),
115-230Kb/s (dažreiz)
7
Balansets interfeiss
VA-VB lt -0.2v 0 VA-VB gt 0.2v1
V.35
RS-422, RS-485, RS-530, V.11, V.35, HSSI Max
atrums 2Mb/s (garantets), 8Mb/s (strada), 52Mb/s
(HSSI)
8
Asinhrona parraide (RS-232)
NullModem

• Pirms parraides abam pusem jauzstada aptuveno
  parraides atrumu (9600, 19200, 38400, 115000bps).
• Funkcionali DCE DTE (atškiras vienigi štepselu
  izskats NullModem)
• Flow Control none, software (CtrlS, CtrlQ),
  hardware (RTS, CTS)

9
RS-232 Signali
10
Sinhrona parraide (V.35)
DCE (modem) ----------- DTE (terminal) Receive
Timing (VX) ----gt Receive Data
(RT) ----gt Transmit Timing (YAA)
----gt Transmit Data (PS) lt---- Terminal Timing
(UW) lt---- TransmitTiming is generated by
DCE (modem) and looped by DTE (terminal) back on
TerminalTiming to compensate for delay
introduced by long cable between DCE and DTE

• Pusem nav javienojas par parraides atrumu to
  vienmer nosaka DCE puse generejot Transmit
  Timing un Receive Timing sinhronizacijas
  signalus
• Funkcionali DCE ? DTE nevar savienot DCE-DCE vai
  DTE-DTE
• Flow Control nav vajadzigs, jo sinhrona parraide

11
Tradicionali lieto tikai...

• Nebalansetu RS-232 interfeisu asinhronai datu
  parraidei (COM porti PC datoriem)
• Peles pieslegšanai
• Modema pieslegšanai
• Balansetu V.35 vai RS-449 interfeisu sinhronai
  datu parraidei
• Izdalitas sakru linijas (64Kb/s 2Mb/s)
• IP, FR, X.25 maršrutizatoru interfeisi

12
Telefonijas interfeisi
Local loop
Trunk

• Local loop
• Analogais
• ISDN BRI
• Trunk
• ISDN-PRI, SS7 (E1)
• SDH

13
Divi ISDN Standarti
ISDN PRI (iestažu telefonucentralu pieslegšanai)
ISDN BRI(gala lietotaju pieslegšanai)
14
ISDN BRI
Channel
Mostly Used for
Capacity
B
Voice, Fax, Data
64 kbps
2B
Terminals
ISDN box
ISDN
NT1
D
Channel
Mostly Used for
Capacity
D
16 kbps
Signaling information (LAPD)
ISDN BRI Integrated Services Digital Network,
Basic Rate Interface
15
ISDN PRI
Channel
Mostly Used for
Capacity
B
Voice, Fax, Data
64 kbps
30B
E1 line
ISDN
1D
Channel
Mostly Used for
Capacity
D
64 kbps
Signaling information (LAPD)
ISDN PRI Integrated Services Digital Network,
Primary Rate Interface
16
SDH

• SDH Synchronous Digital Hierarchy
• Tikai optisks interfeiss definets
• Atrumi 155Mb/s (STM-1) 9.6Gb/s (STM-64)
• Amerika lieto lidzigu standartu SONET un OC-1
  lidz OC-192

17
SDH Frame Structure
STM-1(155Mb/s)
18
SDH Payload Structure
SDH STM-1 (155Mb/s)
SONET OC-1 (52Mb/s)
19
SONET and SDH rates
SONET Electrical
SDH
SONET Optical
Link Rate Mbps
OC-1 STS-1 51.84 OC-3 STS-3 STM-1 155.52 OC-9
STS-9 STM-3 466.56 OC-12 STS-12 STM-4 622.08 OC-18
STS-18 STM-6 933.12 OC-24 STS-24 STM-8 1244.16 OC
-36 STS-36 STM-12 1866.24 OC-48 STS-48 STM-16 2488
.32
20
ATM

• A compromise for voice, data, and video
• Hardware-based cell relay
• Larger frames are segmented and reassembled at
  ATM endpoints
• Can span both LAN and WAN
• Switched and Permanent VCs supported in ATM

Video
Voice
Data
ATM cells

• ATM Asynchronous Transfer Mode
• Jebkuri atrumi no 1Mb/s 9.6Gb/s
• Darbojas virs jebkuras fiziskas parraides vides
• ATM B-ISDN (BroadBand ISDN gt 64Kbps)

ATM 53-octet cells
21
ATM Switching
ATM Cell header (5 Bytes)
22
ATM Fragmentation and Reassembly
Source Address
Information Payload
Frame Check
Dest. Address
Packet
Cell Payload
VPI VCI
VPI VCI
Cell Payload
ATM Cells
VPI VCI
Cell Payload
Cell Payload
VPI VCI
23
ATM problemas

• Aparatura ATM fragmentacijai un de-fragmentacijai
  ir loti darga (liela atruma del to jarealize
  hardware limeni)
• Gruti nodrošinat augstu kvalitati ja tikla
  parslodzes rezultata pazud kada ATM šuna, tad
  reali zud ari visa pakete, kurai ta piedereja.