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Сети и телекоммуникации

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MijZ\e_gb_ ihlhdhf

?s_ h^bg iZjZf_lj k\yaZgguc k i_j_^Zq_c ^Zgguo ba dhfivxl_jZ \ fh^_f — mijZ\e_gb_ ihlhdhf (flow control LZd dZd khklhygb_ l_e_nhgghc ebgbb fh`_l g_ij_^kdZam_fh f_gylvky b khhl\_lkl\_ggh f_gy_lky kdhjhklv i_j_^Zqb fh^_f ^he`_g bf_lv \hafh`ghklv dZd-lh mijZ\eylv ihlhdhf ^Zgguo ihklmiZxsbo hl dhfivxl_jZ — ijblhjfZ`b\Zlv _]h b \gh\v jZaj_rZlv

Kms_kl\m_l ^\Z f_lh^Z mijZ\e_gby ihlhdhf — ©fy]dbcª (software b ©`_kldbcª hardware I_j\uc f_lh^ h[hagZqZ_fuc lZd`_ Z[[j_\bZlmjhc ©XON/XOFFª ij_^mkfZljb\Z_l ihkuedm \ gm`guc fhf_gl \ dhfivxl_j h^gh]h ba ^\mo kbf\heh\ — XOFF (ASCII-dh^ ]h\hjys_]h h lhf qlh i_j_^Zqm ^Zgguo gm`gh ijbhklZgh\blv eb[h XON dh^ — kb]gZeZ ©^h[jhª gZ \hah[- gh\e_gb_ i_j_^Zqb Wlb kbf\heu fh^_f ihkueZ_l ih lhfm `_ dZgZem ih dhlhjhfm b^ml b kZfb ^Zggu_

©@_kldbcª f_lh^ lZd`_ h[hagZqZ_fuc ©CTS/RTSª \f_klh ^\mo ki_pbZevguo kbf\heh\ bkihevam_l ^\Z ijh\h^Z ba klZg^Zjlgh]h dZ[_ey k\yau\Zxs_]h fh^_f k dhfivxl_jhf ^ey \gmlj_ggbo fh^_fh\ — ^\Z dhglZdlZ gZ jZat_f_ dhlhjuf fh^_f \klZ\ey_lky \ kehl Dh]^Z fh^_f ]hlh\ d ijb_fm ihlhdZ ^Zgguo hg ihkueZ_l kb]gZe ih h^ghfm ba wlbo ijh\h^h\ — CTS, « Clear To Sendª Z dh]^Z dhfivxl_j ]hlh\ wlb ^Zggu_ ihkeZlv hg \u^Z_l kb]gZe ih ijh\h^m

RTS — « Ready To Send» .

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DZd ijZ\beh \u[hj h^gh]h ba ^\mo f_lh^h\ mijZ\e_gby ihlhdhf hkms_kl\ey_lky ba dhffmgbdZpbhgghc ijh]jZffu IjZ\^Z g_ \k_ fh^_fu b ijhlhdheu i_j_^Zqb nZceh\ ih^^_j`b\Zxl h[Z f_lh^Z gh _keb ^hklmi_g&76 576emqr_ ihevah\Zlvky bf

B _s_ H:BG klZg^Zjl

KlZg^Zjl RShij_^_ey_l mkljhckl\h ihke_^h\Zl_evgh]h KHF ihjlZ Z bf_ggh jZkiheh`_gb_ dhglZdlh\ \ jZat_f_ b lh dZdb_ kb]gZeu ih dZdbf ijh\h^Zf kh_^bgbl_evgh]h dZ[_ey ihkueZxlky dhfivxl_jhf beb i_jbn_jbcguf mkljhckl\hf ?keb dZdh_-lh mkljhckl\h ©ih^dexqZ_lky ih klZg^Zjlm 56-ª lh wlh ijhklh hagZqZ_l qlh _]h fh`gh kh_^bgblv k dhfivxl_jhf q_j_a ihke_^h\Z-

l_evguc ihjl <k_ \g_rgb_ fh^_fu h[yaZgu hl\_qZlv wlhfm klZg^Zjlm

Ijhlhdheu k\yab

Ijhlhdheu k\yab dhlhju_ \k_]^Z j_Zebah\Zgu \ fh^_f_ gZ ZiiZjZlghf mjh\g_ hij_^_eyxl kZfh_ \Z`gh_ — kdhjhklv i_j_^Zqb b f_lh^ fh^meypbb ZgZeh]h\h]h kb]gZeZ pbnjh\uf kf ©Fh^meypby b ^_fh^meypbyª klj Fh^_f dhlhjuc g_ kh[ex^Z_l gb h^gh]h ba wlbo ijhlhdheh\ ijhklh g_ kfh`_l k\yaZlvky gb k dZdbf ^jm]bf fh^_fhf

Ijhlhdheu ITU-T

< gZklhys__ \j_fy kZfu_ jZkijhkljZg_ggu_ ijhlhdheu k\yab hij_^_eyxlky j_dhf_g^Zpbyfb ,78-7 <hl iheguc kibkhd wlbo klZg^Zjlh\ \ ojhgheh]bq_kdhf ihjy^d_ bo ijbgylby

V.21. Hq_gv ^j_\gbc klZg^Zjl ^ey kdhjhklb [bl k

Bell 103. JZajZ[hlZgguc \ KR: ijhlhdhe gZ [bl k \dexq_gguc \ p_eyo kh\f_klbfhklb \ khklZ\ [he__ iha^gbo j_dhf_g^Zpbc,78-T.

V.22. Lh`_ k_^Zy ^j_\ghklv Kdhjhklv ^h [bl k \hafh`_g hldZl ^h [bl k

Bell 212A. JZajZ[hlZgguc \ KR: ZgZeh] 9 ^ey kdhjhklb

[bl k lZd`_ ih^^_j`b\Z_fuc iha^g_crbfb klZg^ZjlZfb,78-T.

V.22bis. Kdhjhklv ^h [bl k \hafh`_g hldZl ^h [bl k ih klZg^Zjlm 9 >he]h_ \j_fy 9 ELV [ue kZfuf jZkijhkljZg_gguf klZg^Zjlhf

V.32. H[_ki_qb\Z_l kdhjhklv ^h [bl k k \hafh`ghklvx hldZlZ ^h [bl k eb[h i_j_dexq_gby gZ ex[hc ba [he__ f_^e_gguo klZg^Zjlh\

V.32bis. Mkh\_jr_gkl\h\Zgguc \ZjbZgl 9 ij_^m- kfZljb\Zxsbc kdhjhklv ^h [bl k b hldZl ^h

b [bl k

V.34. Ijbgyluc \ bxg_ ] wlhl klZg^Zjl jZkkqblZg gZ kdhjhklv ^h D[bl k b hldZl ^h

D[bl k >h hnbpbZevgh]h ijbgylby wlhl klZg^Zjl [ue ba\_kl_g ih^ mkeh\guf gZa\Zgb_f V.Fast. He bf_y l_ji_gby ^h`^Zlvky ml\_j`^_gby 9 \ ,7U-7 g_kdhevdh nbjf h^gh

\j_fy \uimkdZeb fh^_fu gZ D[bl k kh k\hbf kh[kl\_gguf klZg^Zjlhf V.FC (« Fast

Classª g_ imlZlv k V.Past g_kh\f_klbfuf k V b g_ y\eyxsbfky klZg^Zjlhf ITU-T g_kfhljy gZ ij_nbdk ©9 ª G_dhlhju_ ba wlbo fh^_fh\ \ihke_^kl\bb hdZaZehkv \hafh`gh ©h[mqblvª b klZg^Zjlm 9 iml_f aZf_gu ijh]jZffu \ fbdjhko_f_ IAM Ohly V.FC k_cqZk ihqlb \ur_e ba mihlj_[e_gby fgh]b_ kh\j_f_ggu_ fh^_fu k 9 jZ^b kh\f_klbfhklb ih^^_j`b\Zxl b _]h

‡ Hk_gvx ] [ueZ ijbgylZ gh\Zy \_jkby klZg^ZjlZ 9ihq_fm-lh g_ ihemqb\rZy \hij_db ljZ^bpbb kmnnbdkZ bis), h[_ki_qb\ZxsZy kdhjhklb b D[bl k Ihqlb \k_ \uimkdZ_fu_ k_cqZk fh^_fu k 9 ih^^_j`b\Zxl wlb kdhjhklb

KlZg^Zjl D[bl k gZ fhf_gl gZibkZgby wlhc dgb]b _s_ g_ [ue ijbgyl ITU-7 ihwlhfm kms_kl\mxsb_ klZg^Zjlu k\yab gZ wlhc kdhjhklb fu jZkkfhljbf gb`_ \ jZa^_e_ h nbjf_gguo ijhlhdheZo

Wlhl kibkhd klZg^Zjlh\ ohjhrh beexkljbjm_l bklhjbx jZa\blby b kh\_jr_gkl\h\Zgby fh^_fghc k\yab — ih\ur_gby kdhjhklb b mkeh`g_gby f_lh^h\ fh^meypbb

DZd \b^bl_ ijhimkdgZy kihkh[ghklv fh^_fh\ hl klZg^ZjlZ d klZg^Zjlm jhkeZ hq_gv [ukljh I_j\u_ fh^_fu gZ [bl k jZ[h-" lZeb k lZdhc kdhjhklvx qlh fh`gh [ueh qblZlv l_dkl k wdjZgZ [uklj__ q_f hg lZf ihy\eyeky >he]h_ \j_fy ]hkih^kl\h\Z\rbc klZg^Zjl [bl k lZd`_ \_kvfZ g_lhjhieb\ — i_j_^ZqZ nZceZ jZaf_jhf F[ aZgbfZ_l hdheh qZkZ Fh^_fu gZ D[bl k kijZ\eyxlky k l_f `_ aZ ^_kylv fbgml Z fh^_fm gZ D[bl k ^hklZlhqgh b iylb

Nbjf_ggu_ ijhlhdheu

<j_fy hl \j_f_gb l_ beb bgu_ nbjfu — ijhba\h^bl_eb fh^_fh\ ijboh^beb d \u\h^m qlh bo kh[kl\_ggu_ jZajZ[hldb iha\heyxl bf h[_ki_qblv [he__ \ukhdmx kdhjhklv b emqr__ dZq_kl\h k\yab q_f klZg^Zjlu ,78-7 LZd \hagbdZeb — b ijh^he`Zxl \hagbdZlv — nbjf_ggu_ (proprietary ijhlhdheu k\yab ijbgZ^e_`Zsb_ h^ghc dZdhc-lh nbjf_ b ih^^_j`b\Z_fu_ lhevdh fh^_fZfb wlhc nbjfu Wlb ijhlhdheu g_j_^dh \ub]ju\Zxl \ kjZ\g_gbb k klZg^ZjlZfb ,787b g_ lhevdh \ hlghr_gbb ijhimkdghc kihkh[ghklb — hgb h[eZ^Zxl [hevr_c mklhcqb\hklvx aZsbs_gghklvx hl ihf_o emqr_ ijbkihkZ[eb\Zxlky d hkh[_gghklyf ebgbc

Dhg_qgh ]eZ\guc g_^hklZlhd ex[h]h nbjf_ggh]h ijhlhdheZ — lh qlh k gbf mf_xl jZ[hlZlv lhevdh fh^_fu ^Zgghc nbjfu b ^ey k\yab ih nbjf_gghfm ijhlhdhem gm`gh qlh[u gZ

h[hbo dhgpZo ebgbb [ueb kh\f_klbfu_ fh^_fu IjZ\^Z [hevrbgkl\h fh^_fh\ k nbjf_ggufb ijhlhdheZfb ih^^_j`b\Zxl b h[uqgu_ ijhlhdheu ITU-T lZd qlh \eZ^_e_p lZdh]h fh^_fZ fh`_l [_a ljm^Z k\yau\Zlvky k d_f m]h^gh Gh \h \k_f [e_kd_ _]h fh^_f ihdZ`_l k_[y lhevdh ijb jZ[hl_ k ZiiZjZlhf lhc `_ nbjfu

I_j\uf ba nbjf_gguo ijhlhdheh\ aZ\h_\Z\rbo ihimeyjghklv

[ue ijhlhdhe PEP (Packetized Ensemble Protocol nbjfu Telebit, ihy\b\rbcky _s_ \ ] b h[_ki_qb\Z\rbc lh]^Z kdhjhklv \

D[bl k b ohjhrmx aZsblm hl ihf_o \ ebgbb Fh^_fu Telebit TrailBlazer ih^^_j`b\Z\rb_ wlhl ijhlhdhe [ueb ^h\hevgh ^hjh]bfb mkljhckl\Zfb ihemqb\rbfb rbjhdh_ jZkijhkljZg_gb_ ebrv gZ jZ[hqbo klZgpbyo k hi_jZpbhgghc kbkl_fhc UNIX.

< ] nbjfZ US Robotics \uimklbeZ fh^_f Courier HST \ dhlhjhf [ue j_Zebah\Zg nbjf_gguc ijhlhdhe HST (High Speed Technology kh kdhjhklvx kgZqZeZ \ [bl k Z \ihke_^kl\bb —

b D[bl k < gZqZe_ -o wlhl ijhlhdhe klZe klZg^Zjlhf ^_- nZdlh kj_^b \eZ^_evp_\ b ihevah\Zl_e_c BBS gZ ,%0-kh\f_klbfuo dhfivxl_jZo \h fgh]hf [eZ]h^Zjy lhfm qlh nbjfZ US Robotics ij_^eZ]ZeZ kdb^db kbkl_fguf-hi_jZlhjZf BBS Ihke_^gyy \_jkby ijhlhdheZ +67ih^^_j`b\Z_l kdhjhklb ^h D[bl k gh [eZ]h^Zjy mklhcqb\hc jZ[hl_ gZ iehobo ebgbyo fh^_fu k +67 bgh]^Z ihdZau\Zxl ^Z`_ emqrb_ j_amevlZlu q_f mkljhckl\Z k V.34.

Ke_^m_l mihfygmlv lZd`_ ijhlhdhe V.32terbo dhlhjuc hiylvlZdb g_kfhljy gZ ij_nbdk ©9 ª ijbgZ^e_`bl g_ ,78-7 Z nbjf_ $7 7 Wlhl ijhlhdhe ih^^_j`b\Z_l kdhjhklb ^h D[bl k Bgl_j_kgh qlh ih^^_j`dZ wlh]h ijhlhdheZ gZjy^m kh \k_fb ijhlhdheZfb ,78-7 \ fh^_f_ Courier iha\hebeZ nbjf_ US Robotics ijb^Zlv wlhfm fh^_fm h[hagZq_gb_©9Every thing» .

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ihwlhfm ^hklb`_gb_ lZdhc kdhjhklb g_\hafh`gh [_a g_dhlhjuo mobsj_gbc h dhlhjuo fu m`_ ]h\hjbeb klj — Z bf_ggh h^bg ba k\yau\ZxsbokyAdhfivxl_jh\ ijb wlhf ^he`_g [ulv ih^dexq_g k ihfhsvx ki_pbZevgh]h h[hjm^h\Zgby g_ihkj_^kl\_ggh d pbnjh\hfm ©oj_[lmªl_e_nhgghc k_lb Djhf_ lh]h j_ZebaZpbb wlh]h ijhlhdheZ m`_ g_ y\eyxlky ihegh^mie_dkgufb — kdhjhklv \ D[bl k h[_ki_qb\Z_lky lhevdh \ gZijZ\e_gbb ©hl ijh\Zc^_jZ d ihevah\Zl_exªlh]^Z dZd \ h[jZlghf gZijZ\e_gbb k\yav h]jZgbq_gZ kdhjhklvx D[bl k ih ijhlhdhem9

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KlZg^Zjlu nZdkbfbevghc k\yab

I_j_^ZqZ nZdkh\ l _ ]jZnbq_kdbo bah[jZ`_gbc ^hdmf_glh\ ih l_e_nhgghfm dZgZem ijbgpbibZevgh gbq_f g_ hlebqZ_lky hl i_j_^Zqb dhfivxl_jguo ^Zgguo k ihfhsvx fh^_fZ < nZdk-ZiiZjZl_ bah[jZ`_gb_ kqblZggh_ k ebklZ [mfZ]b i_j_\h^blky \ pbnjh\mx nhjfm — ihlhd gme_c b _^bgbp ^ey i_j_^Zqb dhlhjuo ih l_e_nhgghc ebgbb ijbf_gyxlky l_ `_ ijbgpbiu fh^meypbb b ^_fh^meypbb qlh b \ fh^_f_ <hl ihq_fm l_ogbq_kdb g_ hq_gv keh`gh h[t_^bgblv \ h^ghf mkljhckl\_ fh^_f b nZdk

H^gZdh nZdkbfbevgu_ ZiiZjZlu dhlhju_ jZa\b\Zebkv g_aZ- \bkbfh hl dhfivxl_jh\ bkihevamxl ^ey k\yab kh\k_f ^jm]b_ ijhlhdheu D kqZklvx bo g_ lZd fgh]h

KlZg^Zjlu nZdkbfbevghc k\yab ijbgylh gZau\Zlv ]jmiiZfb NZdku b nZdk-fh^_fu ]jmiiu kihkh[gu i_j_^Zlv h^gm kljZgbpm h[uqgh]h nhjfZlZ ijbf_jgh aZ fbgml K_cqZk lZdZy l_ogbdZ kqblZ_lky m`_ [_agZ^_`gh mklZj_\r_c Mkljhckl\Z ]jmiiu

i_j_^Zxl h^gm kljZgbpm m`_ aZ fbgmlu GZdhg_p kZfu_ kh\j_f_ggu_ ZiiZjZlu ]jmiiu jZ[hlZxl gZ kdhjhklb ^h [bl k bkihevamxl k`Zlb_ ^Zgguo b [eZ]h^Zjy wlhfm kihkh[gu ihkeZlv h^gm kljZgbpm \k_]h aZ k_dmg^

NZdk-ZiiZjZlu ]jmiiu iha\heyxl \u[bjZlv \ aZ\bkbfhklb hl lj_[mxs_]hky dZq_kl\Z dhibb h^gh ba ^\mo agZq_gbc jZaj_rZxs_c kihkh[ghklb — o lhq_d gZ ^xcf \©]jm[hfªb o lhq_d gZ ^xcf \ ©lhgdhfª j_`bf_ ?keb `_ ihfbfh lj_[h\Zgbc d ]jmii_

nZdk beb nZdk-fh^_f ih^^_j`b\Z_l lZd`_ klZg^Zjl V.I 7 ITU-7lh hg kihkh[_g i_j_^Z\Zlv nZdku gZ kdhjhklb ^h D[bl k

<aZbfh^_ckl\b_ nZdk-fh^_fZ k dhfivxl_jhf hij_^_ey_lky ^jm]bf klZg^Zjlhf kh]eZkgh dhlhjhfm \k_ nZdk-fh^_fu ih^jZa- ^_eyxlky gZ ^\Z deZkkZ Mkljhckl\Z deZkkZ mf_xl ebrv k\yau- \Zlvky k nZdkhf beb nZdk-fh^_fhf gZ ^jm]hf dhgp_ ebgbb Z \kx

jZ[hlm ih ij_h[jZah\Zgbx ^Zgguo b mijZ\e_gbx k_Zgkhf k\yab ^he`gZ [jZlv gZ k_[y dhffmgbdZpbhggZy ijh]jZffZ

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iha\heyxl jZa]jmablv ijhp_kkhj dhfivxl_jZ qlh hq_gv ihe_agh dh]^Z nZdku i_j_^Zxlky beb ijbgbfZxlky \ nhgh\hf j_`bf_ l _ h^gh\j_f_ggh k jZ[hlhc ^jm]bo ijh]jZff NZdk-fh^_fu US Robotics ih^^_j`b\Zxl _s_ [he__ kh\_jr_gguc klZg^Zjl jZajZ[hlZgguc wlhc nbjfhc b h[hagZqZ_fuc ©deZkk ª Ih^^_j`dZ nZdk-fh^_fh\ deZkkZ m`_ ihy\beZkv \h fgh]bo ijh]jZffZo ^ey jZ[hlu k nZdkZfb

MklZgh\e_gb_ kh_^bg_gby

<k_ wlh aZf_qZl_evgh — kdZ`_l_ \u — gh dZd `_ fh^_fu j_rZxl ih dZdhfm ijhlhdhem hgb [m^ml h[sZlvky"Ihgylgh \_^v qlh [_a h[s_]h ijhlhdheZ fh^_fu g_ fh]ml h[f_gylvky gb [blhf bgnhjfZpbb — lZd dZd `_ lh]^Z bf m^Z_lky ^h]h\hjblvky h lhf dZdhc ijhlhdhe mklZgh\blv"

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