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1
leqcia
.
8
. s
tandartuli qselebi
lokaluri qselebis Seqmnis momentidan dRemde SemuSavebul
iqna asobiT sxvadasxva qseluri teqnologia, magram maTgan gavrceleba hpova ramodenimem. rac dakavSirebulia, upirveles yovlisa, qselis organizaciis principebis standartizaciis maRali doniT da maTi mxardaWeriT cnobili kompaniebis mier. ganvixiloT yvelaze po
pularuli standartuli lokaluri qselebis aparaturis ZiriTadi Taviseburebebi.
cxr. 6.1
-
Si mocemulia standartuli lokaluri qselebis maxasiaTeblebis klasikuri variantebi. Yyvela standartul qsels gaaCnia ramodenime varianti, romlebic gansxvavdebian gamoyenebuli k
abelis tipiT, gadacemis siCqariT, qselis dasaSvebi zomebiT
Qqselis parametri
Ethernet
Token
-
Ring
Arcnet
FDDI
100VG
-
AnyLAN
standarti
IEEE 802.3
IEEE 802.5
Datapoint
ISO 9314
IEEE 802.12
topologia
saltis
wris
saltis
wris
varskvlavisebri
gadacemis siCqare
10 (100)mbit/wm
(16)mbit/wm
2.5mbit/wm
100mbit/wm
100mbit/wm
sigrZe
5km
120km
6km
20km
1km
garemo
koaqs. kabeli
xv. wyvili
Kkoaqs. kab.
Oopt.
-
boWk.
xv.wyvili
marTvis meTodi
CSMA/CD
markeri
markeri
markeri
centri
kodi
manCesteris
bifazuri
Arcnet
4B/5B
5B/6B
raodenoba
1024
-
mde
260
-
mde
255
-
mde
1000
-
mde
1024
-
mde
Ethernet и Fast Ethernet qselebi
standartul qselebs Soris
yvelaze
farTo
gavrceleba hpova Ethernet
qselma
. Ppirvelad is gamoCnda 1972 wels (romelic SeimuSava kompania Xerox
-
ma). Qqseli 2
sakmaod warmatebuli aRmoCnda da 1980 wels mxari dauWires cnobilma komp
aniebma, rogoricaa DEC
da Intel
(am kompaniebis gaerTianebas daerqva DIX
)
.
M1985 wels ki Ethernet
gaxda saerTaSoriso standarti, romelic miiRo umsxvilesma saerTaSoriso standartebis organizaciam: komiteti 802 IEEE
(Institute of Electrical and Electronic Engi
neers) и ECMA (European Computer Manufacturers Association).
standartma miiRo saxelwodeba IEEE 802.3
-
is saxiT. is gansazRvravs mravaljerad wvdomas saltis tipis monoarxTan, amasTanave aRmoaCens konfliqtebs da akontrolebs gadacemas, anu CSMA/CD
wvdomis meTo
diT. IEEE 802.3
standartis maxasiTeblebi:
?
topologia ?
saltisebri;
?
gadamcemi garemo ?
koaqsialuri kabeli;
?
gadacemis siCqare ?
10mbit/wm;
?
qselis maqsimaluri sigrZe ?
5km;
?
abonentebis maqsimaluri raodenoba ?
1024
-
mde;
?
qselis segmentis sigrZe ?
500m
-
mde;
?
abon
entebis raodenoba erT segmentze ?
100
-
mde;
?
wvdomis meTodi -
CSMA/CD
;
?
mcirezoliani gadacema, e.i. modulaciis gareSe (monoarxi).
Ethernet
qseli amJamad Zalian popularulia msoflioSi (bazris 90%
-
ze mets ikavebs). Mmisi popularoba gamoiwvia imanac, rom Tavidan
ve qselis maxasiTeblebi, parametrebi, da protokolebi
Ria
iyo
,
ris Sedegadac mwarmoeblebis didi ricxvi uSvebda Ethernet
-
is aparaturas, romlebic erTmaneTTan iyvnen Tavsebadi.
Ethernet
klasikur qselSi gamoiyeneboda 50
-
omiani koqsialuri kabeli ori tipis (msx
vili da wvrili). Tumca 90 wlebidan farTo gavrceleba hpova Ethernet
-
is versiam
xveuli wyvilis bazaze. agreTve gansazRvrulia standarti optikur
-
boWkovani kabelis gamoyenebiT. 1995 wels Seiqmna Ethernet
-
is
ufro swrafi versiis standarti, romelic muSaobda 100mbi
t/wm siCqareze (e.w. Fast Ethernet
, стандарт IEEE 802.3u
), romelic gadamcem garemod iyenebs xveul wyvils an optikur
-
boWkovan kabels. 1997 wels Seiqmna versia 1000mbit/wm siCqareze (
Gigabit Ethernet, стандарт IEEE 802.3z).
3
saltis standartuli topologiis gard
a Zalian farTod gamoiyeneba pasiuri varskvlavisa da pasiuri xis topologiebi. Aam SemTxvevaSi gamoiyeneba repiterebi da repiteruli koncentratorebi, romlebic aerTeben qselis sxvadasxxa nawilebs (segmentebs). ris Sedegadac formirdeba xisebri struqtura sxvadas
xva tipis segmentebze (nax.6.1)
Nnax.6.1. Ethernet qselis klasikuri topologia
segmentad SeiZleba gamoyenebul iqnas klasikuri salte anu erTeuli abonenti. salturi segmentebisTvis gamoiyeneba koaqsialuri kabeli, xolo pasiuri varskvlavis SemTxvevaSi (konce
ntratorTan kompiuterebis SesaerTeblad) ?
xveuli wyvili da optikur
-
boWkovani kabelebi. mTavari moTxovnilebaa mocemuli topologiisadmi ?
ar iyos masSi Caketili gzebi (petlebi). Ffaqtiurad gamodis, rom yvela abonenti mierTebulia fizikur saltesTan. radganac sig
nali yoveli abonentidan vrceldeba yvela mimarTulebiT da ukan aRar brundeba (rogorc wris SemTxvevaSi).
Kkabelis maqsimaluri sigrZe mTlianobaSi Teoriulad aRwevs 6.5 km
-
s, magram praqtikulad ar aRemateba 3.5 km
-
s. 4
Fast Ethernet
qselSi saltis topologia ar ari
s gaTvaliswinebuli, masSi gamoiyeneba mxolod pasiuri varskvlavi da xe. Fast Ethernet
qselSi ufro mkacri moTxovnebia qselis sigrZis mimarT. gadacemis siCqaris 10
-
jer gazrdisas da paketis formatis dacvisas, misi minimaluri sigrZe 10
-
jer mcirdeba. amasTanave 10
-
jer mcirdeba qselSi signalis gavlis ormagi drois dasaSvebi sidide (5,12mkwm nacvlad 51,2mkwm
-
isa Ethernet
-
Si).
informaciis gadasacemad Ethernet
qselSi gamoiyeneba manCesteris kodi.
wvdoma Ethernet
qselSi xorcieldeba SemTxveviTi CSMA/CD
meTodiT, romel
ic uzrunvelyofs abonentebis Tanasworobas. qselSi gamoiyeneba cvalebadi sigrZis paketebi Semdegi struqturiT (nax. 6.2) (ricxvebiT aRniSnulia baitebis raodenoba).
nax.6
.2 Ethernet
qselis paketis struqtura
Ethernet
kadri (anu paketi preambulis gareSe) und
a Seadgendes araumcires 512
-
bitian intervals anu 51,2 mkwm
-
s (daaxloebiT Ees aris qselSi gavlis ormagi drois zRvruli sidide). gaTvaliswinebulia individualuri, jgufuri da farTomauwyeblobiTi damisamarTeba.
Ethernet
paketSi Sedis Semdegi velebi:
?
preambula, ro
melic Sedgeba 8 baitisagan, pirveli Svidi warmoadgens kods 10101010, xolo ukanaskneli ?
10101011 kods. IEEE 802.3 standartSi me
-
8 baits uwodeben kadris sawyiss (
SFD ?
Start of Frame Delimiter
) da warmoqmnis paketis calkeul velebs.
5
?
mimRebis (gadamcemis) da gadamcemis (mimRebis) misamarTebi Secaven 6 baits TiToeuli, romlebic miniWeba xdeba standartebis mixedviT. samisamarTo velebi muSavdeba abonentebis aparaturiT.
?
marTvis veli (
L/T ?
Length/Type
) Seicavs informacias monacemTa velis sigrZeze. mas SeuZlia agreT
ve gansazRvros gamoyenebuli protokolis tipi. Tu am velis mniSvneloba 1500
-
ze meti ar aris, maSin is miuTiTebs monacemTa velze. Tu aRemateba, maSin is gansazRvravs kadris tips. marTvis veli muSavdeba prgoramulad.
?
monacemTa veli unda Seicavdes 46
-
dan 1500 ba
itamde monacemebs. Tu paketi Seicavs 46 baitze nakleb monacemebs, maSin monacemTa veli ivseba baitebiT. IEEE 802.3
standartis mixedviT paketis struqturaSi gamoiyofa specialuri Sevsebis veli (
pad data
?
umniSvnelo monacemebi
), romelsac SeiZleba hqondes nulo
vani sigrZe, roca monacemebi sakmarisia (metia 46 baitze).
?
sakontrolo jamis veli (
FCS ?
Frame Check Sequence
)
Seadgens paketis 32
-
Tanriga ciklur sakontrolo kods (
CRC
), romelic amowmebs paketis gadacemis siswores.
maSasadame, kadris (paketis preambulis gar
eSe) sigrZe Seadgens 64 baits (512 bits). saxeldobr es sidide gansazRvravs qselSi maqsimalurad dasaSveb ormag dayovnebas 512 bitian intervalSi (51,2 mkwm Ethernet
-
Tvis an 5,12 mkwm
-
s Fast Ethernet
-
Tvis). standartis mixedviT preambula SeiZleba Semcirdes pa
ketis gavlisas sxvadasxva qselur mowyobilobebSi gavlisas, amitomac mas ar iTvaliswineben. Kkadris maqsimaluri sigrZe tolia 1518 baitis (12144 bitis, e.i. 1214,4 mkwm Ethernet
-
Tvis an 121,44 mkwm
-
s Fast Ethernet
-
Tvis). es Zalian mniSvnelovania qseluri mowy
obilobis buferuli mexsierebis zomis SesarCevad da qselis zogadi datvirTvis Sesafaseblad.
Ppreambulis formatis SerCeva SemTxveviTi ar aris. erTianebisa da nulebis (101010...10) monacvleoba manCesteris kodSi xasiaTdeba imiT, rom gadasvlebi am SemTxvevaSi mxo
lod bitur intervalebSi xdeba (sainfromacio gadasvlebi). TavisTavad sakmarisia mimRebi dayendes (dasinqrondes) aseTi TanmimdevrobiT im SemTxvevaSic Tu is ramodinime bitiT mcirdeba. Bxolo ori erTeuli biti (11) arsebiTad gansxvavdeba 101010...10 kombinaciisga
n (gadasvlebi xdeba bituri intervalebis sazRvarzec). 6
Aamitomac ukve dayenebuli mimRebi advilad arCevs maT da arCevs sasrgeblo informaciis dasawyiss (kadris dasawyisi).
Ethernet
qselisTvis, romelic muSobs 10 mbit/wm siCqariT, standarti gansazRvravs qselis s
egmentis oTx ZiriTad tips, romlebic orientirebulia gadacemis garemos sxvadasxva tipebze:
?
10
BASE
5 (msxvili koaqsialuri kabeli);
?
10
BASE
2 (
wvrili
koaqsialuri kabeli);
?
10BASE
-
T (
xveuli wyvili
);
?
10BASE
-
FL
(
optikur
-
boWkovani kabeli
).
s
eg
m
e
ntis dasaxel
eba moicavs sam elements: cifri ?10? niSnavs gadacemis siCqares ?
10 mbit/wm, sityva BASE
?
gadacemas sixSireTa ZiriTad zolSi (e.i. maRalsixSiriani signals modulaciis gareSe), xolo bolo elementi ?
segmentis dasaSveb sigrZes: ?5? ?
500metrs, ?2? ?
200metrs (ufro swored 185 metrs) an kavSiris arxis tips: ?T?
-
xveuli wyvili (
"twisted
-
pair"
)
, "F"
?
optikur
-
boWkovan kabels (
"fiber optic")
.
zustad aseve Ethernet
qselisTvis, romelic muSobs 100 mbit/wm siCqariT (
Fast Ethernet
)
,
standarti gansazRvravs qselis segmenti
s sam ZiriTad tips, orientirebuls informaciis gadacemis garemos sxvadasxva tipebze:
?
100
BASE
-
T
4
(gaoTxmagebuli xveuli wyvili);
?
100
BASE
-
TX
(gaormagebuli xveuli wyvili);
?
100BASE
-
FX (optikur
-
boWkovani kabeli).
A
aq cifri ?100? niSnavs gadacemis siCqares -
100
mbit/wm, ?T?
-
xveuli wyvils (
"twisted
-
pair"
)
, "F"
?
optikur
-
boWkovan kabels (
"fiber optic")
. 1
00BASE
-
TX da 100BASE
-
FX
zogjer erTiandebian 100BASE
-
X
-
is qveS, xolo 1
00BASE
-
T4 da 100BA
SE
-
T
X
-
100BASE
-
T ?
is qveS. Ethernet
-
is teqnologiebi viTardeba da Zve
li standartebisgan sakmaod gansxvavdeba. Aaxali gadacemis garemosa da komutatorebis gamoyeneba arsebiTad zrdis qselis maStabebs. manCesteris kodis xmarebidan amoReba (
Fast Ethernet
da Gigabit
Ethernet
qslebSi
) zrdis monacemTa gadacemis siCqares da amcirebs
moTxovnebs kabelis mimarT. CSMA/CD
7
marTvis meTodis
xmarebidan amoReba (gacvlis srul dupleqsur reJimSi) saSualebas iZleva mkveTrad gazardos muSaobis efeqturoba da moixsnas SezRudva qselis sigrZeze. qselis axal saxecvlibebesac Ethernet
?
s uwodeben.
Eth
ernet/Fast Ethernet qselebis algoriTmebi
rogorc ukve aRiniSna CSMA/CD (Carrier
-
Sense Multiple Access with Collision Detection ?
mravajeradi wvdoma gadamtanis kontroliT da koliziebis aRmoCeniT) meTodi miekuTvneba decentralizebul SemTxveviT meTodebs (ufro s
wored, kvazi
-
SemTxveviT meTodebs). is gamoiyeneba, rogorc Cveulebriv Ethernet qselSi, aseve maRalsiCqarian qselebSi (Fast Ethernet, Gigabit Ethernet). TviT meTodis s
axelwodeba
s aqvs Semdegi istoria. Aadreul qselSi (
Alohanet),
romelic funqcionirebda 1970 w
els havais kunZulebze, gamoiyeneboda radioarxi da muSaobda Tanamgzavrze retranslatorze (aqedan warmoiqmna sityva ?gadamtani? mis saxelwodebaSi). Ggarda am meTodisa gamoiyeneboda ufro martivi meTodic (koliziebis aRmoCenis gareSe). CSMA meTodi Ethernet da Fa
st Ethernet
qselebSi gadamtanis funqcias asrulebs sinqrosignali, romelic ereva gadasacem informacias, romelic uzrunvelyofs saimedo sinqronizacias mimRebis mxares, romelic xorcieldeba signalis damatebiTi iZulebiTi gadasvlebis xarjze or (rogorc manCester ?
I
I
-
is kodSi) an sam eleqtrul dones Soris (rogorc Ethernet 100BaseT4
-
is kodis SemTxvevaSi oTxi araekranirebuli (
UTP) xveuli wyvilis bazaze). Kklasikuri CSMA meTodisgan gansxvavebiT CSMA/CD meTodSi damatebulia gadacemis momentSi koliziebis aRmoCena, rac zrdis
informaciis gadacemis siCqares. Ethernet da Fast Ethernet
qselebis droiTi diagramebi aRwerisas da agreTve paketebis (kadrebis) sigrZeebis SemTxvevaSic gamoiyeneba Semdegi terminebi:
8
?
IPG
(interpacket gap, paketTaSorisi xvreli) ?
minimaluri drois intervali
gadasacem paketebs (9,6
mks
Ethernet
-
Tvis
/ 0,96
mks
Fast Ethernet
-
Tvis
)
Soris. meore saxelwodeba ?
kadrTaSorisi intervali.
?
ВТ (Bit Time,
bitis dro) ?
drois intervali erTi bitis gadasacemad (100nwm Ethernet
-
Tvis
/ 10
wm
Fast Ethernet
-
Tvis
)
.
?
PDV (Path Delay
Value, gzaSi dayovnebis dro)
-
signalis gavlis dro qselis or kvanZs Soris (wriuli anu gaormagebuli). iTvaliswinebs jamur dayovnebas sakabelo sistemaSi, qselur adapterebSi da sxva qselur mowyobilobebSi.
?
Collision window (koliziebis fanjara) ?
PDV
-
s maqsimal
uri mniSvneloba mocemuli segmentisaTvis.
?
Collision domain (koliziebis are, konfliqtis zona) ?
qselis nawili, sadac adgili aqvs kolizias
?
Slot time (arxis dro) ?
segmentisTvis maqsimaluri dasaSvebi fanjara (
512? ВТ
) ?
Minimum frame size ?
kadris minimaluri sidide (512 biti).
?
Maximum frame size ?
kadris maqsimaluri sidide (1518 biti).
?
Maximum network diameter ?
(
qselis maqsimaluri diametri) ?
segmentis dasaSvebi maqsimaluri diametri, romlis drosac koliziebis fa
njara ar aRematebs Slot time
-
s,
arxis dros.
?
Truncated binary exponential back off (
orobiTi Sekvecili eqsponencialuri dayovneba
)
?
dayovneba Semdgomi paketis gadacemis win koliziebis Semdgom (miRebulia 16 mcdeloba). gamoiTvleba Semdegi formulis mixedviT:
R
AND(0,2
min(N,10)
) x 512
x ВТ
sadac N
?
mTvlelis mcdelobaTa ricxvi, RAND(a,b) normalurad ganawilebuli
mTeli ricxvebis
generatori a?b diapazonSi ukanaskneli cifris CaTvliT. Mmocemuli parametri icvleba diapazonSi ?
paketis minimaluri sigrZe an qselSi signalis gavrcelebis maqsimalu
ri dasaSvebi ormagi dayovneba (
PDV
).
9
q
selis wvdomis algoriTmi
. nax.5.1
-
ze naCvenebia qselis wvdomis struqturuli sqema CSMA/CD
-
is
meTodis Sesabamisad, sadac gadasacemad gamoiyeneba kadrebi.
Kkadris dasawyisidan, romelic daniSnulia gadasacemad, abonenti (kv
anZi) aformirebs pakets. Semdgom informaciis blokebis aRniSvnisas, romlebic gadaicema qselSi CSMA/CD ?
is algoriTmis gamoyenebisas, cneba ?kadri? da ?paketi? ar gansxvavdebian rig SemTxvevebSi. praktikaSi adgili aqvs aseT SemTxvevebs.
Tu paketis momzadebis Semdeg qseli Tavisufalia, abonents (kvanZs) ufleba aqvs daiwyos gadacema. Mmagram pirvel rigSi man unda Seamowmos gavida Tu ara minimaluri dasaSvebi IPG
dro wina gadacemis Semdeg (naxazze bloki1). mxolod IPG
drois damTavrebis Semdgom abonents SeuZlia gadas
ces Tavisi paketi. bitebis gadacema (bloki 2 naxazze).
Yyoveli bitis gadacemis Semdeg abonenti amowmebs konfliqtis (koliziis) arsebobas qselSi. Tu kolizia ar aris, bitebis gadacema grZeldeba paketis damTavrebamde (bloki4 naxazze). am SemTxvvvaSi iTvleba, r
om gadacema warmatebulad damTavrda.
Tu romelime bitis gadacemisas aRmoCenil iqna kolizia, maSin gadacema wydeba. Aabonenti (kvanZi) aZlierebs kolizias 32
-
bitiani signalis sacobis (
JAM
) gadacemiT da iwyebs mzadebas Semdeg mcdelobaze gadasces (bloki 3 naxazz
e). signali sacobi garantias iZleva, rom kolizias aRmoaCenen sxva abonentebic, romlebic monawileoben konfliqtSi.
signalis sacobi gadacemis Semdeg, romelmac aRmoaCina kolizia, zrdis mTvlelis mcdelobaTa ricxvs (gadacemis dasawyisSi mTvleli imyofeboda or mdgo
mareobaSi). MmcdelobaTa maqsimaluri ricxvi ar unda aRematebodes 16
-
s, amitom Tu mTvleli gadaivso, paketis gadacemis mcdeloba Sewydeba. Aam SemTxvevaSi qseli Zalian gadatvirTulia, masSi koliziebis ricxvi Zalian didia. Mmocemuli situacia avariulia da muSavd
eba ufro maRal doneebze gacvlis protokolebis meSveobiT.
Tu mcdelobaTa ricxvma 16
-
s ar gadaaWarba, maSin gamoiTvleba dayovnebis dro mocemuli formulis mixedviT, Semdgom ki gamoTvlili droiTi intervalis gamZleoba
. Ddayovnebis sididis SemTxveviToba albaTomis ma
Rali xarisxiT miuTiTebs imaze, rom konfliqtSi monawile yvela abonents dayovnebis sidide eqnebaT sxvadasxva. Semdgom paketis gadacemis mcdeloba meordeba Tavidan. xolo abonenti, romlis gamoTvlili dayovnebis sidide naklebia, gadacemas daiwyebs pirvelad da dab
lokavs sxva danarCens.
10
Tu gadacemis moTxovnis gamoCenis momentSi (paketis momzadebis damTavrebis Semdgom) qseli dakavebulia meore abonentis mier, maSin mocemuli abonenti elodeba qselis ganTavisuflebas (bloki5 naxazze). Qselis ganTavisuflebis Semdgom is und
a adelodos IPG dros wina gadacemidan sakuTari gadacemis dawyebamde. Ees dakavSirebulia kvanZis swrafqmedebiT, romelic amowmebs gadamtanis arsebobas (garemos dakavebulobas ama Tu im gadamcemi abonentis mier).
maSasadame, CSMA/CD meTodi ar axdens koliziebis Tavidan acilebas, aramed piriqiT, gvTavazobs da axdens mis provocirebas, xolo Semdgom agvarebs. mag. Tu gadacemaze moTxovnebi erTdroulad warmoimSva ramodenime abonentis mier, qselis ganTavisuflebis Semdgom yvela es abonenti erTdoulad iwyebs gadacemas, ris Sedegadac warmoiqmneba kolizia. koliziebi warmoiqmneba im SemTxvevaSic, roca qseli Tavisufalia, xolo MmoTxovnebi gadacemaze ramodenime abonents warmoeqmneba erTdroulad. sityva ?erTdroulad? niSnavs signalis ormag gavlas qselSi intervalis farglebSi, anu 512
-
bitian intervalis farglebSi. zustad 512
-
bitiani intervalis farglebSi xdeba koliziebis aRmoCena qselSi.
Tu koliziis aRmoCena moxdeba 480
-
bitian intervalamde, maSin warmoimneba paketebi, romelTa sigrZe naklebi iqneba minimalur dadgenil sazRvarze 512
-
bitian i
ntervalebis farglebSi (64 baiti) signalis ?sacobi? damatebiTac. aseT paketebs (kadrebs) uwodeben karlikurs (
runt frames
). Tu kolizia
warmoiqmna (480
-
bitiani intervalis Semdeg), maSin paketi SeiZleba iyos dasaSvebi sigrZis (signal sacobTan erTad). aseT pake
tebs vuwodoT karlikuri arakoreqtuli iqneba. signali sacobi, romelic warmoqmnis paketis 32 ukanasknel bitebs, SeiZleba gamodges sakontrolo jamad. Tumca albaToba imisa, rom sacobi Seesabameba paketis swor sakontrolo jams, usasrulod mcirea ( daaxloebiT 1 SemT
xveva 4.2 miliardidan).
koliziebi
(paketebis gadafarTva erTmaneTiT) aRmoCenil unda iqnas gadacemis dasrulebamde. analizi yoveli miRebuli paketis bolos FCS
, faqtiurad dabrkolebebisadmi mdgrad ciklur kods
CRC (Cyclic Redundancy Check) Seicavs, gamoiwvevda ga
dacemis siCqaris mkveTrad dacemas.
praqtikulad koliziebi
s aRmoCena xdeba gadamcemi abonentis mier an qselis gammeoreblebis mier, romelic SesaZlebelia gafuWebuli paketis gadacemis damTavrebamde. Tu gaviTvaliswinebT, rom qselis sigrZe lokalur qselSi Ethernet
/ Fast Ethernet SeiZleba iyos diapazonSi 64
-
dan 1518 baitamde da Tugadacemis adreuli Sewyveta da xazis ganTavisufleba niSnavs qselis gamtarunarianobis efeqtianobis SesamCnevad gazrdas.
11
koliziebis pirveli niSania signalis sacobis warmoqmna gadamcemi abonen
tis mier paketis gadacemis dros. sxva niSnebia:
?
paketis sigrZe 64 baitze (512 biti) naklebia;
?
paketi Seicavs araswor sakontrolo jams FCS (
ufro swore
d
, araswor ciklur kods);
?
paketis sigrZe ar aris 8
-
is jeradi.
dabolos, Ethernet qselSi gamoiyeneba
kodi manCe
steri
-
II da aparaturuli meTodi koliziis gansasazRvravad, romelic efuZneba signalis saSualo mniSvnelobis gadaxris analizs 0
-
dan.
Zalian datvirTuli qselis SemTxvevaSic ki erTi abonentisaTvis Tanmimdevruli koliziebis ricxvi 3
-
s ar aRemateba. es aixsneba gada
cema moTxovnis warmoSobis SemTxveviTi xasiTiT da koliziis SemTxvevaSi Semdegi gadacemis mcdelobis gadadebis diskretuli mniSvnelobiT. koliziebis ricxvi miT metia, rac metia segmentis diametri da rac ufro Sors arian ganlagebuli abonentebi intensiuri trafik
iT.
qselis warmadobis Sefaseba
. qselis warmadobis Sefaseba wvdomis SemTxveviTi meTodis CSMA/CD SemTxvevaSi naTlad ar aris gamosaxuli ramodenime maxasiTeblis arsebobis gamo. upirveles yovlisa, unda aRiniSnos erTmaneTTan dakavSirebuli sami maTTagani, romleb
ic axasiaTeben qselis warmadobas idealur SemTxvevaSi ?
koliziebis ararsebobis dros da paketebis uwyveti nakadis gadacemisas dayofils paketTaSorisi intervaliT IPG
. cxadia, aseTi rejimis realizeba SesaZlebelia Tu erTi abonenti aqtiuria da gadascems paketebs maqsimaluri siCqariT. gamtarunarianobis ara sruliad gamoyeneba garda IPG
intervalisa dakavSirebulia Ethernet
paketSi samsaxurebrivi velebis arsebobiT (nax.5.2).
maqsimaluri sigrZis paketi ufro Warbia samsaxurebrivi informaciis wilTan SedarebiT. is Seicavs 12304 bits (
IPG
intervalis CaTvliT), maTgan 12000 sasargeblo monacemebia.
amitomac paketebis gadacemis maqsimaluri siCqare (anu siCqare kabelSi -
wire speed)
Fast Ethernet qselis SemTxvevaSi Seadgens 10
8
bit
/
wm
/ 12304 bit
≈ 8127,44 paketi
/
wm
.
gamtarunarianoba
?
s?a??lo??ro?miis????es?iCq??aoc?? ?????i
toli?
8127,44 paketi
/
wm
x 1500 baiti
≈ 12,2 mb
/
wm
.
12
Qqselis gadacemis fizikuri siCqaris gamoyenebis efeqturoba
Fast Ethernet ?
is (
100 mbit/wm
) SemTxve
vaSi Seadgens
8127,44 paketi
/
wm
x 12000 biti
/ 10
8
biti
/
wm
≈ 98%.
Minimaluri sigrZis mqone
paketis gadacemisas kabelSi siCqare arsebiTad izrdeba. amasTanave gamtarunarianoba da efeqturoba SesamCnevad (TiTqmis 2
-
jer) uaresdeba samsaxurebrivi informaciis wil
is gazrdis gamo.
realuri qselebisaTvis, rogoricaa kerZod Fast Ethernet
didi raodenobi|T abonentebis SemTxvevaSi gamtarunarianoba 12,2 mbait/wm zogierTi abonentisTvis pikia, anu iSviaTad realizebadi mniSvnelobaa. Yyvela abonentis erTnairi aqtivobisas saSual
o gamtarunarianoba TiToeulisTvis Seadgens 12,2/
N
mbait/wm, magram sinamdvileSi SeiZleba naklebi iyos koliziebis SemTxvevaSi, qseluri aparaturis Secdomebis SemTxvevaSi da dabrkolebeblis zemoqmedebis Sedegad (roca lokaluri qseli musaobs iseT pirobebSi, roca sakabelo sistema ganicdis didi garegani eleqtromagnituri velebis zemoqmedebas). D
realuri qselebisaTvis warmadobis iseTi maCvenebeli, rogoricaa qselis gamoyenebis maCvenebeli (
network utilization
) ufro informatiulia da is Seadgens jamuri gamtarunarianobis wils procentebSi. is iTvaliswinebs koliziebs da sxva faqtorebsac. Aarc servers da arc arcerTi muSa sadgurs ar gaaCnia saSualebebi qselis gamoyenebis maCveneblis gansasazRvravad, amisaTvis gamoiyeneba aparaturul
-
programuli saSualebebi, rogoricaa qselis ana
lizatorebi. Mmagram yovelTvis ar aris xelmisawvdomi maRalis Rirebulebis gamo.
iseTi datvirTuli qselebisaTvis, rogoricaa Ethernet da
Fast Ethernet
, qselis gamoyenebis maCveneblis yvelaze optimaluri mniSvnelobaa 30%. Ees mniSvneloba Seesabameba qselis muSaob
as xangrZilivi gaCerebebis gareSe da uzrunvelyofs sakmao marags datvirTvis pikuri gazrdis SemTxvevaSi. Tumca qselis gamoyenebis maCvenebeli Tu Sedgens 80...90%
-
s da mets, es miuTiTebs resursebis mTlianad gamoyenebaze, magram ar tovebs marags SemdgomisTvis.
r
ealuri qselebisaTvis, mag. Fast Ethernet
-
is SemTxvevaSi es aris hipoteturi
situacia.
13
Nnax.5.2.
-
ze mocemulia qselis gamoyenebis maCveneblis damokidebuleba droze im pirobiT, rom SemoTavazebuli datvirTva (
offered load
), anu mimdinare moTxovna gamtarunariano
baze, wrfivad izrdeba. Tavidan qselis gamoyenebis maCvenebeli wrfivad iqrdeba, xolo Semdgom konkurencia garemos dakavebaze iwvevs koliziebs. Aamitom ganxiluli maCvenebeli aRwevs maqsimums (sruli datvirTvis wertili grafikze). xolo SemoTavazebuli daTvirTvis Semdgomi gazrdisas qselis gamoyenebis maxasiaTebeli iwyebs klebas, gansakuTrebiT mkveTrad gajerebis wertilis Semdgom. Ees qselis muSaobis ?cudi? area. iTvleba, rom qseli kargad muSaobs, Tu SemoTavazebuli datvirTva da qselis gamoyenebis maCveneblebi maRalia
.
Nnax.5.2. qselis gamoyenebis maCveneblis damokidebuleba droze SemoTavazebuli daTvirTvis wrfivi zrdis SemTxvevaSi
(1
-
muSaobis yvelaze kargi are, 2
-
misaRebi, 3
-
cudi) Token Ring
Llokaluri qselis teqnologia Token Ring Seiq
mna IBM
-
is mier 1970 wels. IBM
-
ma warudgina mocemuli standarti Sesabamis komitets (
IEEE LAN standards committee),
romelmac
mouwona da 14
daamtkica, rogorc
IEEE 802.5
standarti. Token Ring
-
is topologiebi ganixileba, rogorc f
izikuri varskvlavuri da logikuri wr
iuli topologiebi. (nax.9.1.)
Nnax.9.1. Token Ring
-
is topologia
Token Ring
-
is qselebi erTi kvanZidan
meoremde atareben signals
, romelic cnobilia, rogorc markeri (
token
)
.
kvanZs, romlisganac
gadmoicema signali, uwodeben zeda mezobel kvanZs, xolo, romels
ac gadaecem
a, qveda mezo
bel kvanZs. yoveli kvanZi miiRebs markers, asrulebs garkveul moqmedebas da Semdgom gadascems qveda mezobels. (nx.9.2.)
15
N
n
ax
.8.3. Token Ring
-
is operaciebi
Ooperaciebi sruldeba im momentSi, roca kvanZi akontrolebs markers. roc
a kvanZi akontrolebs markers, is gadascems mas qveda mezobel kvanZs. romelic markeris miRebis Semdeg gadascems mas Semdeg qveda mezobel kvanZs. monacemebs agrovebs yoveli kvanZi
.
Token Ring
,
iseve rogorc, Ethernet xasiaTdeba
ganawilebuli
gadamcemi garem
os tipiT, romelic Sedgeba erTmaneTTan kabelebiT SeerTebuli kompiuterebisagan. wre ganixileba, rogorc gadacemis saerTo
resursi da masTan wvdomisaTvis gamoiyeneba determinirebuli algoriTmi, romlis Sesabamisad wreSi CarTuli kompiueterbi wres iyeneben gansazRv
ruli TanmimdevrobiT specialuri formatis kadris meSveobiT, romelsac uwodeben markers (
token
).
Token Ring
teqnologia SeimuSava IBM kompaniam 1984 wels, xolo 1985 wels IEEE komitetma daakanona da miiRo Sessabamisi 802.5 standarti. IBM kompania Token Ring
teq
nologias iyenebs, rogorc ZiriTad qselur teqnologias lokaluri qselebis asagebad sxvadasxva tipis kompiuterebis bazaze. dgesdgeobiT IBM kompania awarmoebs
qseluri adapterebis 60 %
-
s am teqnologiiT. 16
Token Ring
qselebi muSaoben 4 da 16 mbit/wm siCqareebiT. sx
vadasxva siCqareebiT momuSave kompiuterebis erT wreSi CarTva dauSvebelia. Token Ring
teqnologia ufro rTuli teqnologiaa, vidre Ethernet. is gamoirCeva mtyunebebisadmi mdgradobiT. Token Ring
qselebSi gansazRvrulia qselis muSaobis kontrolis procedurebi, roml
ebic iyenebn ukukavSirs wrisebr struqturaSi ?
ukanaskneli kadri yovelTvis ubrundeba gadamcems. Qqselis gasakontroleblad momuSave sadgurebidan erTerTi asrulebs aqtiuri monitoris rols. aqtiuri monitori SeirCeva wris inicializaciis dros, rogorc kompiuteri MA
C
-
misamarTis maqsimaluri mniSvnelobiT. Tu aqtiuro monitori gamodis mwyobridan, maSin wris inicializacia meordeba da airceva axali aqtiuri monitori. Qqselma rom aRmoaCinos aqtiuri monitoris mtyuneba ukanaskneli muSa mdgomareobaSi yofnisas yovel 3 wamSi afor
mirebs specialur kadrs, romelic miuTiTebs aqtiuro monitoris mwyobrSi yofnas. Tu es kadri ar gamoCnda 7 wamis ganmavlobaSi maSin sxva sadgurebi iwyeben axali monitoris SerCevis proceduras.
Mmarkeruli wvdoma gadamcem garemoze
Mmarkeruli wvdomis qselebSi
(
Token Ring
-
is garda miekuTvneba FDDI, ArcNet) garemoze wvdomis ufleb sadguridan sadgurs gadaecema ciklurad logikuri wreSi.
Token Ring
qselebSi yoveli sadguri dakavSirebulia mxolod or mezobel sadgurTan da mxolod maTTan SeuZlia gacvalos monacemebi. sadguri
s garemosTan wvdomis uzrunvelsayofad wreSi cirkulirebs specialuri formatisa da daniSnulebis kadri ?
markeri. Token Ring
qselebSi yoveli sadguri monacemebs iRebs mxolod erTi sadguridan, roemlic mis win mdebareobs wreSi. aseT sadgurs ewodeba axlo aqtiuri mez
obeli ?
Neares Active Upstream Neighbor, NAUN. xolo yoveli sadgulir monacemebs gadascems masTan qvemoT myof sadgurs -
Neares Active Downstream Neighbor, NADN.
17
M
m
arkeris miRebis Semdeg
sadguri analizs ukeTebs mas da Tu ar gaaCnia monacemebi, maSin markeri g
adaecema Semdeg sadgurs. sadguri ki, romelmac unda gadasces monacemebi, markeris miRebisas iRebs wridan mas, rac garemosTan wvdomis da monacemebis gadacemis uflebas aZlevs. Semdeg es sadguri wreSi gadascems winaswar dadgenili formatis monacemTa kadrs bitob
iT Tanmimdevrulad. Gadacemuli monacemebi wreSi gaivlian mxolod erTi da igive mimarTulebiT erTi sadguridan meoremde. Kkadri Seicavs mimRebisa da da gadamcemis misamarTebs.
N
nax.9.1.
markeruli wvdomis principi
wris yvela sadguri axdens kadris bitobiT re
translirebas, rogorc gammeorebeli. Tu kadri gadis daniSnulebis sadgurs, maSin Tavisi misamarTis amocnobisas es sadguri akopirebs 18
kadrsTavis Sida buferSi da kadrSi svams damadasturebel niSans miRebaze. sadguri, romelic gadascems kadrs wreSi, misi ukan miReb
isas miRebis dadasturebiT wridan iRebs am kadrs da uSvebs axal markers, rom misces SesaZlebloba qselis sxva sadgurebs gadascen monacemebi. wvdomis aseTi meTodi gamoiyeneba Token Ring
-
is qselebSi, romlis siCqarea 4mbit/wm (standarti 802.5).
nax.9.1.
-
ze droi
Ti diagramiT aRwerilia garemos wvdomis algoriTmi. sadac A paketi gadaicema wreSi, romelic Sedgeba 6 sadgurisagan, 1 sadguridan me
-
3
-
s. daniSnulebis sadguris gavlis Semdeg A pakets eniWeba ori parametri ?
misamarTis amocnobis nisani da paketis buferSi ko
pirebis niSani. (naxazze mocemulia varskvlaviT paketze). Ppaketis 1 sadgurze dabrunebis Semdeg gadamcemi Tavisi paketis amocnobisas wridan iRebs mas. Mme
-
3 sadguris mier dayenebuli niSnebi imaze miuTiTebs gamgzavns, rom misi paketi mivida adresatTan da wa
rmatebulad dakopirda Tavis buferSi.
Ggadamcemi garemos dakavebis dro Token Ring
qselebSi ganisazRvreba markeris dakavebis droiT (
token holding time
). am drois amowurvis Semdeg sadguri valdebulia Sewyvitos sakuTari monacemebis gadacema (mimdinare kadris das
ruleba nebadarTulia) da markeri gadaecema wreSi. F
FDDI (Fiber Distributed Data Interface)
Fiber Distributed Data Interface
(FDDI)
-
ganawilebuli monacemebis optikurboWkovani interfeisi ?
es lokaluri qselebis pirveli teqnologiaa, romelSic ga
damcem garemod gamoiyeneba optikur
-
boWkovani kabeli.
FDDI
standartis Tavdapirveli versiebi uzrunvelyofen kadrebis gadacemas 100 mb/wm siCqariT ormag optikur
-
boWkovan wreSi 100 km
-
is sigrZeze. FDDI teqnologiis
ZiriTadi maxasiaTeblebi
es teqnologia efuZn
eba Token Ring
-
is teqnologias, sadac misi ZiriTadi ideebi da srulyofili gaxda. am teqnologiis Seqmnisas prioritetuli iyo Semdegi miznebi:
?
monacemTa gadacemis siCqaris gazrda 100 mb/wm
-
de;
19
?
qselis dabrkolebebisadmi mdgradobis amaRleba qselis aRdgenis sxvadas
xva standartuli procedurebis xarjze, rogoricaa kabelis dazianeba, kvanZis, koncentratoris arakoreqruli muSaoba, xazze maRali donis dabrkolebebis warmoqmna da a.S.
?
qselis poteancialuri gamtarunarianobis maqsimalurad efeqtiurad gamoyeneba, rogorc asinqronuli
aseve sinqronuli (
dayovnebebisadmi mgrZnobiare
)
trafikisaTvis.
FDDI qseli
agebulia ori optikur
-
boWkovani wreebis bazaze, romlebic qmnian monacemTa gadacemis ZiriTad da sarezervo gzebs qselis sxvadasxva kvanZevs Soris.
ori wris arseboba -
FDDI q
selSi dabrk
olebebisadmi mdgra
dobis amaRlebis ZiriTadi xerxia, sadac kvanzebi, romlebsac surT isargeblon saimedoobis am amaRlebuli potencialiT, unda iyvnen dakavSirebulni am orive wresTan.
normalur reJimSi qselis muSaobisas monacemebi gaivlian pirveladi (
Primary
) wri
s yvela ubans. am reJims ewodeba Thru ?
?
gamWoli? anu ?tranzituli?. meoradi (
Secondary
) wre am rejimSi ar gamoiyeneba.
romelime saxis mtyunebis SemTxvevaSi, r
oca pirveladi wris nawils ar S
euZlia gadasces monacemebi (mag. kabelis gawyveta an kvanZis mtyuneb
a), pirveladi wre uerTdeba meorads (nax. ), romelic isev qmnis erTian wres.
qselis muSaobis am reJims ewodeba Wrap anu wreebis daxveva. daxvevis
operacia swarmoebs habebis
an FDDI qseluri adapterebis meSveobiT.
am proceduris gasaadvileblad monacemebi pirve
lad wreSi gadaicema erTi mimarTulebiT (diagramebze es mimarTuleba aRiniSneba saaTis isris sawinaaRmdego mimarTulebiT), xolo meorad wreSi ki sawinaaRmdego mimarTulebiT (saaTis isris mimarTulebiT). amitom saerTo rgolis warmoqmnis SemTxvevaSi ori wris mier, g
adamcemebi uwindeburad rCebian kavSirSi mezobeli sadgurebis mimRebebTan, rac saSulaeba
s iZleva sworad gadaices da miiR
os informacia mezobeli sadgurebisagan.
FDDI standartebSi didi yuradReba eTmoba sxvadsxva porcedurebs, romlebic saSualebas iZlevian aRmoaC
inon mtyuneba, xolo Semdgom ki Sesrulebul iqnas aucilebeli rekonfiguracia. FDDI qsels SeuZlia srulebiT aRadginos funqcionireba calkeuli elementebis mtyunebebis SemTxvevaSi. mravalricxovani mtyunebebis SemTxvevaSi ki qseli iSleba sxvadasxva qselebad, romleb
sac erTmaneTTan ara aq kavSiri. FDDI teqnologias
, Token Ring
-
is teqnologiisgan gansxvavebiT, mtyunebebis aRmoCenis meqanizms gaaCnia qselis monacemTa gadacemis gzebis 20
rekonfiguraciis meqanizmic, romelic efuZneba sarezervo kavSirebs, romlebic uzrunvelyofen
meorad wres.
nax. .. FDDI wreebis rekonfiguracia mtyunebis SemTxvevaSi
FDDI standartebSi wre ganixileba, rogorc monacemTa gadacemis saerTo ganawilebuli garemo
, amitomac misTvis ganisazRvreba wvdomis specialuri meTodi.
es meTodi Zalian hgavs Token
Ring
-
is
qselebis wvdomis meTods da aseve ewodeba markeruli wris (anu Tokenuri)
-
Token Ring
-
is meTodi.
wvdomis meTodis gansxvaveba imaSia, rom markeris dakavebis dro FDDI qselSi ar aris mudmivi sidide, rogorc Token Ring
-
is
qselebSi. es dro damokidebulia w
ris CatvirTvaze ?
didi datvirTvisas izrdeba, xolo mcire datvirTvis SemTxvevebSi SeiZleba Semcirdes 0
-
mde.
es cvlilebebi exeba mxolod asinqronul trafiks, romelic ar aris kritikuli kadrebis gadacemis mcire dayovnebebis mimarT. xolo sinqronuli trafikisaTvis m
arkeris dakavebis dro iseve ucvlelia.
kadrebis prioritetebis meqanizmi, rogorc Token Ring
-
is
teqnologiis SemTxvevaSi, FDDI teqnologiaSi ar arsebobs.
radganac specialistebma trafikis dayofa 8 doned miiCnies zedmetad da CaTvales saWirod trafikis dayofa 2 kla
sad ?
sinqronulad da asinqronulad
, sadac ukanasknelis momsaxureba SesaZlebelia wris gadatvirTvis SemTxvevaSic ki.
21
danarCen SemTxvevaSi kadrebis gadagzavna wris sxvadasxva sadgurebs Soris MAC
-
is doneze Seesabameba Token Ring
-
is
teqnologias. FDDI ?
is sadgu
rebi iyeneben markeris adreuli ganTavisuflebis algoriTms, rogorc Token Ring qselebSi 16 mbit/wm siCqariT.
MAC
-
is doni
s misamarTebs gaaCniaT
IEEE 802 teqnologiisaTvis standartuli formati
. FDDI kadr
is formats Token Ring
-
is formatisagan gansxvavdebiT ar Se
icavs mxolod prioritetebis velebs.
nax....
-
ze mocemulia FDDI teqnologii
s
protokolebis struqturis Sesabamisoba 7
-
doniani OSI model
Tan. FDDI gansazRvravs fizikuri donis protokols da arxulis donis (MAC) garemos qvedonis protokols. rogorc lokaluri qseleb
is sxva teqnologiebSi
, FDDI teqnologiaSic gamoiyeneba monacemTa arxis martvis qvedonis protokoli LLC, romelic gansazRvrulia 802.2 standartSi.
nax.... FDDI teqnologiis protokolebis struqtura
FDDI teqnologiis ganmasxvavebeli Taviseburebaa sadguris marT
vis done
?
Station Management (SMT).
SMT
asrulebs FDDI protokolebis stekis yvela sxva danarCeni donis marTvisa da monitoringis funqciebs.
wris marTvaSi FDDI
-
is yvela kvanZi iRebs monawileobas. amitom yvela kvanZs Soris mimdinareobs SMT
kadrebis gacvla qsel
is marTvisaTvis.
22
FDDI teqnologiis Sedareba Ethernet da Token Ring teqnologiebTan
cxr.
-
Si warmodgenilia FDDI teqnologiis Sedareba Ethernet da Token Ring teqnologiebTan
maxasiaTeblebi
FDDI
Ethernet
Token Ring
siCqare
topologia
wvdomis meTodi
monacem
Ta gadacemis garemo
100mbit/wm
xeebis ormagi wre
markeris uku drois nawili
optikur
-
boWkovani, me
-
5 kategoriis araekranirebuli xveuli wyvili
10mbit/wm
salte/varskvlavi
CSMA/CD
msxvili
koaqsialuri, wvrili koaqsialuri, me
-
3 kategoriis xveuli wyvili,
optikur
-
boWkovani
16mbit/wm
varskvlavi/wre
darezervebis prioritetuli sistema
ekranirebuli da araekranirebuli xveuli wyvili, optikuri boWko
ARCnet
ARCnet (
anu ing. Attached Resource Computer NETwork
) ?
es aris
lokaluri qselis teqnologia, romelsac ig
ive daniSnuleba aqvs, rogorc Ethernet
-
sa da Token Ring
-
s. ARCnet
pirveli teqnologiaa mikro kompiuterebis qselebis Sesaqmnelad, romelic Zalian popularuli gaxda 1980
-
ian wlebSi. daniSnulia loklauri qselebis organizebisaTvis qseluri topologiiT ?varskvlavi?.
s
akomunikacio mowyobilobebia: komutatori (
switch
) da aqtiuri/pasiuri habi.
23
am mowyobilobebidan meti upiratesobiT sargeblobs komutatori, radganac is qseluri domenebis Seqmnis saSulaebas iZleva. aqtiuri habebi gamoiyeneba muSa sadgurebis did manZilebze yofnis
SemTxvevaSi
(isini aRadgenen signalis formas da aZliereben). pasiuri habebis ki mokle manZilebze gamoiyeneba. qselSi gamoiyeneba muSa sadgurebis gansazRvruli wvdomis principi, e.i. gadacemis ufleba aqvs im sadgurs, romelic serverisgan iRebs e.w. programul
markers.
e.i. xdeba determinirebuli qseluri trafikis realizeba.
midgomis upiratesobebi:
?
SasaZlebelia monacemTa gadacemis paketis miRebis zusti dro.
?
SesaZlebelia qselis gamtarunarianobis zustad gansazRvra.
zRvruli teqnikuri maxasiaTeblebi:
?
erT kabelTan mie
rTebul muSa sadgurebs Soris minimaluri manZili ?
0.9m;
?
yvela grZeli marSrutis maqsimaluri sigrZe ?
6km.
SezRudvebi dakavSirebulia aparaturuli dayovnebebTan informaciis gadacemisas komutirebadi elementebis didi ricxvis SemTxvevaSi.
?
pasiur habsa da muSa sadg
urs Soris maqsimaluri sigrZea 30sm;
?
aqtiur da pasiur habs Soris maqsimaluri sigrZea 30sm
?
aqtiur habebs Soris ?
ki 600sm.
Rirebulebebi: qseluri mowyobilobebis dabali Rirebuleba da didi manZilebze qselebis Seqmnis SesaZlebloba.
naklovanebebi: monacemTa gadace
mis dabali siCqare.
Ethernet
teqnologiis danergvis Semdeg ARCnet
-
ma farTo gavrceleba hpova CaSenebul sistemebSi. 
Автор
v.aslanishvili
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