HDLC(high-level data link control\u9ad8\u968e\u8cc7\u6599\u9023\u7d50\u63a7\u5236)
bit-oriented\u5354\u5b9a,\u70basynchronous serial line(\u540c\u6b65\u4e32\u5217\u7dda),sdlc\u7684iso\u7248 <\/p>\n\n\n\n
1979\u5e74ISO\u540c\u610f\u8a8d\u53ef,\u76ee\u524d\u570b\u969b\u9593\u50b3\u905e\u8cc7\u6599\u7684\u5171\u540c\u6a19\u6e96
\u4ee5\u4f4d\u5143\u70ba\u55ae\u4f4d\u7684\u540c\u6b65\u901a\u8a0a,\u5728\u7dda\u8def\u7576\u4e2d\u50b3\u9001\u7684\u8cc7\u6599\u5fc5\u9808\u8981\u4ee5\u5c01\u5305\u70ba\u6700\u5c0f\u50b3\u9001\u55ae\u4f4d
\u5e38\u7528\u65bc\u79df\u7528\u5c08\u7dda\u4e0a\u7684\u9ede\u5c0d\u9ede\u5354\u5b9a
\u53ef\u7528\u96fb\u8def\u4ea4\u63db\u6216\u662f\u5c01\u5305\u4ea4\u63db\uff0c\u652f\u63f4\u9ede\u5c0d\u9ede\u6216\u662f\u4e3b\u5f9e\u67b6\u69cb\u7684\u7db2\u8def\uff0c\u61c9\u7528\u5341\u5206\u5ee3\u6cdb
\u597d\u8655\u662f\u53ef\u4e00\u6b21\u50b3\u9001\u591a\u8a0a\u6846\uff0c\u4e26\u5c0d\u6bcf\u500b\u55ae\u7368\u8a0a\u6846\u6aa2\u67e5\u932f\u8aa4\uff0c\u53ef\u9760\u6027\u8207\u50b3\u8f38\u901f\u5ea6\u90fd\u6bd4BISYNC\u512a\u826f
\u6a19\u6e96HDLC:\u652f\u63f4\u55ae\u4e00\u5354\u5b9a
ps:\u601d\u79d1\u5c08\u5c6cHDLC,\u652f\u63f4\u591a\u5354\u5b9a,\u8a0a\u6846\u591aproprietary\u6b04\u4f4d
ps:\u5176\u4ed6\u5ee0\u5546\u7684hdlc\u4e5f\u662f\u81ea\u5bb6\u5ee0\u5546\u5c08\u5c6c\u7684,\u5404\u5ee0\u5546\u7684hdlc\u7121\u6cd5\u4e92\u901a
\u5de5\u4f5c\u7ad9\u985e\u578b\u5206,\u4e3b\u8981(\u767c\u6307\u4ee4),\u6b21\u8981(\u56de\u61c9\u6307\u4ee4),\u6df7\u5408(\u53ef\u767c\u6307\u4ee4\u548c\u56de\u61c9),<\/p>\n\n\n\n
\u914d\u7f6e\u65b9\u5f0f\u5206
\u4e0d\u5e73\u8861(\u591a\u9ede\u914d\u7f6e,\u4e00\u4e3b\u8981\u591a\u6b21\u8981\u5de5\u4f5c\u7ad9)
\u5c0d\u7a31,\u5be6\u4f53\u5de5\u4f5c\u7ad9\u542b\u908f\u8f2f\u4e3b\u8981\u548c\u908f\u8f2f\u6b21\u8981,\u800c\u908f\u8f2f\u4e3b\u8981\u6709\u53e6\u4e00\u689d\u7dda\u9023\u5230\u53e6\u4e00\u5be6\u4f53\u5de5\u4f5c\u7ad9\u7684\u908f\u8f2f\u6b21\u8981
\u5e73\u8861(\u9ede\u5c0d\u9ede,\u7528\u6df7\u5408\u5de5\u4f5c\u7ad9)
\u901a\u8a0a\u6a21\u5f0f\u5206
NRM(normal response mode,\u6a19\u6e96\u56de\u61c9\u6a21\u5f0f):\u4e0d\u5e73\u8861\u914d\u7f6e\u7528,\u7531\u4e3b\u8981\u555f\u59cb
ARM(asynchronous response,\u975e\u540c\u6b65\u56de\u61c9\u6a21\u5f0f):\u5c0d\u7a31\u914d\u7f6e\u7528,\u7531\u4efb\u4e00\u908a\u5be6\u4f53\u7684\u908f\u8f2f\u4e3b\u8981\u555f\u59cb
ABM(asynchronous balanced,\u975e\u540c\u6b65\u5e73\u8861\u6a21\u5f0f):\u5e73\u8861\u914d\u7f6e\u7528,\u4efb\u4e00\u908a\u7686\u53ef\u555f\u59cb<\/p>\n\n\n\n
\u8a0a\u6846\uff1a\u6709I-frame,S-frame,U-frame\u4e09\u7a2e\u985e\u578b
flag(\u65d7\u6a19):\u5e8f\u521701111110\uff1a8bit\u8a0a\u6846\u7684\u754c\u7dda,\u8b93\u63a5\u6536\u8005\u8fa8\u8b49\u8a0a\u6846\u7684\u8d77\u59cb\u548c\u7d50\u675f\u7684\u540c\u6b65\u6a23\u6b65
bit stuffing(\u4f4d\u5143\u586b\u88dc\u7a0b\u5e8f):\u5728\u9023\u7e8c5\u500b1\u5f8c\u52a00,\u907f\u514d\u8aa4\u8a8d\u70ba\u662fflag\u7528
address(\u4f4d\u5740)\uff1a\u8b8a\u52d5bit,\u8fa6\u8b58\u90a3\u500b\u7d42\u7aef\u6a5f\u7528,8bit\u53ef\u8fa8\u8b582^7\u53f0,\u56e0\u6700\u5f8c\u4e00\u4f4d\u662f\u56fa\u5b9a1,\u82e5\u8d85\u904e\u5247\u6bcfbyte\u6700\u5f8c\u4e00\u4f4d\u70ba0
control(\u63a7\u5236)\uff1a8bit\u4ee5\u4e0a,\u7528\u65bc\u5e8f\u865f,\u56de\u61c9…\u7b49,\u6709\u4f7f\u7528piggybacking\u6280\u8853
information(\u8cc7\u8a0a\u8a0a\u6846)I-frame:0(1bit)+seq(3bit)+p\/f(1bit)+next(3bit)
seq:\u9001\u51fa\u7684\u4f4d\u5143\u5e8f\u865f
next:\u9810\u671f\u4e0b\u4e00\u500b\u8a0a\u6846\u7684\u5e8f\u865f
p\/f:bit=0\u7121\u610f,bit=1\u6709poll\u5fb5\u8a62(\u4f4d\u5740\u8868\u63a5\u6536\u8005\u662f\u4e3b\u7ad9\u9001\u6b21\u7ad9)\/final\u7d50\u675f(\u4f4d\u5740\u8868\u50b3\u9001\u8005\u662f\u6b21\u7ad9\u9001\u4e3b\u7ad9)\u610f\u7fa9
supervisory(\u4e3b\u63a7\u8a0a\u6846)S-frame:10(2bit)+type(2bit)+p\/f(1bit)+next(3bit)
\u78ba\u8a8d,\u6d41\u91cf\u63a7\u5236,\u932f\u8aa4\u63a7\u5236\u7528
type:0 RR(receive ready,\u56de\u61c9\u8a0a\u6846)
1 REJ(reject,\u5426\u5b9a\u56de\u61c9\u8a0a\u6846),\u932f\u8aa4\u88ab\u5075\u6e2c,\u50b3\u9001\u7aef\u8981\u91cd\u9001next\u958b\u59cb\u6240\u6709\u8a0a\u6846
2 RNR(receive not ready,\u66ab\u505c\u50b3\u9001),\u63a5\u6536\u7aef\u767c\u751f\u554f\u984c,\u5982\u7de9\u885d\u5340\u4e0d\u8db3
3 SREJ(selective reject,\u91cd\u50b3),SDLC\u548cLAPB\u4e0d\u5141\u8a31
unnumbered(\u672a\u7de8\u865f\u8a0a\u6846)U-frame:11(2bit)+type(2bit)+p\/f(1bit)+modifier(3bit)
\u7528\u4f86\u9054\u5230\u63a7\u5236\u7684\u76ee\u5730,\u5404\u7a2e\u4f4d\u5143\u5c0e\u5411\u5354\u5b9a\u5dee\u7570\u5927
type+modifier\u53ef\u670932\u7a2e\u4e0d\u540cu-frame,\u53ef\u5206\u4e94\u7a2e\u63a7\u5236\u6307\u4ee4\u8207\u56de\u61c9
\u6a21\u5f0f\u8a2d\u5b9a:\u6307\u4ee4\u6709SNRM,SNRME,SARM,SARME,SABM,SABME
\u672a\u7de8\u865f\u4ea4\u63db:\u6307\u4ee4\u6709UI,\u56de\u61c9\u6709UI,UA
\u4e2d\u65b7\u9023\u7dda:\u6307\u4ee4\u6709DISC\u4e2d\u65b7,\u56de\u61c9\u6709DM\u4e2d\u65b7\u6a21\u5f0f,RD\u8981\u6c42\u4e2d\u65b7
\u8d77\u59cb\u6a21\u5f0f:\u6307\u4ee4\u6709SIM,\u56de\u61c9\u7528RIM
\u5176\u4ed6:\u6307\u4ee4\u6709REST,XID,\u56de\u61c9\u6709FRMR
proprietary(\u5c08\u5c6c):\u6a19\u6e96hdlc\u7121\u6b64\u6b04\u4f4d\u53ea\u652f\u63f4\u55ae\u4e00\u5354\u5b9a,\u4f46\u5404\u5ee0\u5546\u7684hdlc\u6703\u6709\u6b64\u6b04\u4f4d\u4ee5\u652f\u63f4\u591a\u91cd\u5354\u5b9a
data(\u8cc7\u6599):\u4efb\u610f\u9577\u5ea6,\u4f46\u904e\u9577\u6703\u4f7f\u6aa2\u67e5\u78bc\u6548\u7387\u8b8a\u5dee,I-frame\u542b\u4f7f\u7528\u8005\u8cc7\u6599,U-frame\u53ef\u80fd\u542b\u7ba1\u7406\u8cc7\u8a0a
checksum(\u6aa2\u67e5\u7e3d\u548c)2\u62164byte\uff1acrc(\u5faa\u74b0\u5197\u4f4d\u6aa2\u67e5\u78bc)
flag(\u7d50\u675f\u65d7\u6a19):\u5e8f\u521701111110<\/p>\n\n\n\n
U-frame\u7684\u63a7\u5236\u6307\u4ee4\u8207\u56de\u61c9
DISC(DISConnect):\u6a5f\u5668\u5ba3\u544a\u81ea\u5df1\u5373\u5c07\u7d50\u675f
SNRM(set normal response mode,\u8a2d\u5b9a\u6b63\u5e38\u56de\u61c9\u6a21\u5f0f)\uff1a\u8b93\u6a5f\u5668\u56de\u5230\u7dda\u4e0a,\u5f37\u8feb\u5e8f\u865f\u5f9e0\u958b\u59cb,\u975e\u5c0d\u7a31\u5f62\u5f0f(HDLC,LAPB\u984d\u5916\u547d\u4ee4)
SABM(set asynchronous balanced mode,\u8a2d\u5b9a\u975e\u540c\u6b65\u5e73\u8861\u6a21\u5f0f)\uff1a\u5c07\u7dda\u8def\u91cd\u8a2d\u4e26\u5ba3\u544a\u5169\u908a\u662f\u5c0d\u7b49\u7684
FRMR(FRaMe reject,\u8a0a\u6846\u62d2\u7d55)\uff1a\u8a0a\u6846\u6b63\u78ba\u4f46\u8a9e\u610f\u6709\u8aa4
UA(unnumbered acknowledgement,\u672a\u7de8\u865f\u56de\u61c9):\u63a7\u5236\u8a0a\u6846\u6f0f\u5931\u6216\u640d\u58de\u6642\u56de\u61c9
UI(unnumbered information,\u672a\u7de8\u865f\u8cc7\u8a0a)\uff1a\u53ef\u542b\u4efb\u610f\u8cc7\u8a0a
\u5176\u4ed6\u63a7\u5236\u8a0a\u6846<\/p>\n\n\n\n
……………………………………………………………..<\/p>\n\n\n\n
\u5f9e1981\u5e74\u958b\u59cb\uff0cITU-T\u767c\u5c55\u4e00\u7cfb\u5217hdlc\u7684\u884d\u751f\u5354\u5b9a,\u88ab\u7a31\u70balink access protocol(\u9023\u7d50\u5b58\u53d6\u5354\u5b9a),\u5982\u4e0b
LAP(link access procedure,\u93c8\u7d50\u5b58\u53d6\u7a0b\u5e8f)\uff1ahdlc\u7684ccitt\u4fee\u6539\u7248,\u505a\u70bax.25\u7db2\u8def\u754c\u9762\u6a19\u6e96\u4e00\u90e8\u4efd
LAPB(LAP balanced,\u5e73\u8861\u5f0f\u93c8\u7d50\u5b58\u53d6\u7a0b\u5e8f)\uff1alap\u4fee\u6539\u7248,hdlc\u7c21\u5316\u800c\u4f86\u7684\u5b50\u96c6\u5408
\u7528\u4f86\u9023\u7d50\u4e00\u53f0\u5de5\u4f5c\u7ad9\u5230\u7db2\u8def,\u53ea\u63d0\u4f9b\u4e00\u4e9bDTE\u548cDCE\u9593\u901a\u8a0a\u6240\u9700\u57fa\u672c\u63a7\u5236\u529f\u80fd(\u4e0d\u5305\u62ecpoll\u548cselect\u7684\u5b57\u5143)
\u53ea\u7528\u5728\u5169\u8a2d\u5099(\u6df7\u5408\u578b\u5de5\u4f5c\u7ad9)\u5e73\u8861\u914d\u7f6e\u4e2d,\u901a\u8a0a\u4ee5ABM(\u975e\u540c\u6b65\u5e73\u8861\u6a21\u5f0f)\u9032\u884c,\u73fe\u4eca\u7528\u5728ISDN\u7684B\u983b\u9053
LAPD(LAP\uff0dD Channel,D\u983b\u9053\u93c8\u7d50\u5b58\u53d6\u7a0b\u5e8f)\uff1aHDLC\u7c21\u5316\u800c\u4f86\u7684\u5b50\u96c6\u5408
\u4e3b\u8981\u529f\u80fd\u6709Flow Control(Sliding Windows Mechanism),Error Control(CRC Generation and Check),Sequence Control(\u9806\u5e8f\u63a7\u5236)
\u901a\u8a0a\u63a1ABM\u975e\u540c\u6b65\u5e73\u8861\u6a21\u5f0f,\u7528\u5728ISDN\u7684D\u983b\u9053(out-of-band signaling,\u983b\u5e36\u5916\u50b3\u8a0a\u63a7\u5236\u7528)
LAPM(LAP for modem,\u6578\u64da\u6a5f\u93c8\u7d50\u5b58\u53d6\u7a0b\u5e8f):\u7528\u5728\u6578\u64da\u6a5f\u4e0a\u7684hdlc\u7c21\u7cbe\u7248\u5b50\u96c6\u5408
\u8a2d\u8a08\u5728\u975e\u540c\u6b65\u548c\u540c\u6b65\u9593\u7684\u8f49\u63db,\u932f\u8aa4\u63a7\u5236\u548c\u91cd\u9001
LAPF(LAP for frame-relay):\u7528\u5728frame-relay\u4e0a\u7684hdlc\u7cbe\u7c21\u7248\u5b50\u96c6\u5408<\/p>\n","protected":false},"excerpt":{"rendered":"
HDLC(high-level data link cont …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"fifu_image_url":"","fifu_image_alt":"","_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[28],"tags":[],"class_list":["post-829","post","type-post","status-publish","format-standard","hentry","category-wan"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts\/829","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/comments?post=829"}],"version-history":[{"count":0,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts\/829\/revisions"}],"wp:attachment":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/media?parent=829"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/categories?post=829"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/tags?post=829"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}