DSL HOWTO for Linux
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5. 僷僼〖儅儞僗ˇ僠儏〖僯儞僌僩Q僽O僔儏〖F傿儞僌

5.1. 僠儏〖僯儞僌

傕x鲁偟y昛岒偟y偄傞傢偗偱偡偑丄傗偼傝≈R〖僾斊眶 9佷偱昛偟偨偄偺偑媞澓 偱偟x丅偝傜庐偔丄赖偟偔偡傞悢彋偼偄偺偱偟x乆

Linux 偺僱僢僩R〖僋懹墙偼丄僨僼͙O僩偱晹傕"僠儏〖僯儞僌"偟y 偄偄榏擭偱傕傝动蜗偱偡丅偦傟鈻湝晹傕偡傞涩懨偑偄傕偟傟偣傫丅 偟偟戃偟y偄偨傎偳鲁偑偍傕傢偟偔偄崤孿丄偳偙b玛偑偁傞嵽墙漟偑 偁傝偡丅"旝摌"娕傪錃傟傞傛傝傕傗偭y傒傞嶤栆偑偁傞傕 偟傟偣傫丅

y傕偍偍偞偭傁誊墱偱偡偑丄R络戃庐刨 偼渏㑤傝偡丅偙傟偼攔櫷搉偁傞 DSLAM 傜偺调违焊曮偝傟偡丅

  喈0-12 K ft ?0-3.6 km) 喈- 2000 Kbps or more (8100 max for ADSL)
  12-16 K ft (3.6-4.6 km) - 1500 Kbps -> 1000 Kbps
  16-18 K ft (4.6-5.4 km) - 1200 Kbps ->  512 Kbps
  18-?? K ft (5.4-?? km)?nbsp;- 喈512 Kbps ->  ?28 Kbps or less :(

偄偢傟偟y傕丄读傪涂偊傞Û偊傜傟傞懨朤偼偨偔偝傫偁傝偡丅 敡崳棇 DSL 偼偙偺Y傗柺费懹墙偺傛x馄懅摌鈡傪悷湩嗌帘偟y偄偔 偱偟x丅

僱僢僩R〖僋偺僆〖僶〖僿僢僪(TCP 傗 ATM丄僀〖僒僱僢僩)傛偭y丄儌僨L偑湩槰 嵽墙戃庐刨偑 10 20 % 屺偪傞偱偟x丅1500 Kbps 偱偺鲁 傜U 1100 1300 Kbps 镍刨偱昛偔鍆偄偡丅偙傟偑晬湩偺庐刨偱偡丅泴傒欫傒 S傒偺僾僩僐O偺僆〖僶〖僿僢僪傪漝腊偡傞涩懨偼偁傝偣傫丅偨丄僾僶僀僟 偑漵g偡傞庐刨傛傝僒〖J僗偺剂傪屺偟y偄傟U丄晹傪偟y傕偦傟鈻湝偼偁偑傝 偣傫丅 偨〗搀傗奡规偺墒剂丄偦傟傕x庐刨滦偟y读 傪涂偊傞懨朤偼嘎傝偔偁傝偡丅偦偺柺偼扩偱偒傞傕偺傕偁傝偡丅

5.1.1. TCP Receive Window

鋛奶傜丄僨僼͙O僩偱僀儞僗僩〖O偟y偄傞 Linux 偱R搘漟墙偑偱傞偼偢偱偡丅 WIndows 9x 儐〖僓偼 TCP Receive Window (RWIN)傪笼傗偡偙偱粪庐刨偑 湝偑傝偡丅偟偟偙傟偼偁傝戃栆偑堜偝偡偓傞偨{弹偙傝偡丅僨僼͙O 僩偺栆偑 32 KB 偱偁傞 Linux 丄偙傟偼偭偨偔碰y偼傝偣傫丅

焫殅偼丄她漟鲁偪偑弹偙傞崤孿偱偡丅偨偊U丄夺偔偁傞僾僶僀僟偺 鲁僀儞僩偑偢偭鍥扙偊偄傎偳偺觅变(250ms 鈻湝乆)傪嫨偟y偄傞 傜丄 TCP Window 傪笼傗偡偔傞傕偟傟偣傫丅TCP Receive Window 傗 偦傟馄懅偟偨祸奰偮偄y偼丄 http://www.psc.edu/networking/perf_tune.html 傪y偔偩偝偄丅

Receive Window 偼僶僢僼傽偱丄僨〖E僼〖偺扩Œ舔堃偭y偄偡丅偙傟傪O旣 堜偝偔偡傞丄儃僩O僱僢僋Ñ偭y丄僗O〖僾僢僩偑你晍偟y偟偄偡丅偙偺 栆偼丄棭漚b觅变傛偭y焊曮偝傟偡丅觅变偼偁偨偑偔 奶奡偡傞椝缄偺QC儞僪ˇ僩P僢僾E僀L(RTT)偺巑栆偟y纷卢偱偒偡丅偙傟偼 ping傪鍥偭y卢擭偱偒偡丅偨偊U Linux 偺僨僼͙O僩偺栆偼 32 KB 偱偡偑丄偙傟偼庐刨偱 2 Mbps 偱滦鄗偱偒丄觅变偼 125ms 镍刨㑤傝偡丅 偙傟偑 1.0 Mbps 傜U丄觅变偼 250ms Ñ傞偱偟x丅偙偺栆傪偁傝络偒偔偟 檈偓傞丄僗O〖僾僢僩偑拕屺偪y偟偄偡丅偱偡傜偙傟鈻湝偼络偒偔偟偄 偱偔偩偝偄丅

焫傪偄偨偩偄偨僯儏〖l〖Q儞僪偺 Juha Saarinen 颊暷偟偡丅

tcp 偺僶僢僼傽傪湝缄宠扙偡傞偺丄"僱僢僩R〖僋悇(bandwidth delay product丅僄儞僪僀儞僩偺僷僀僾偺吕偝)"偄x撅樜缄烥 偑偁傝偡丅

喈喈喈Buffer size = Bandwidth (bits/s) * RTT (seconds)

讳偺崤孿偩丄晍傝偱偍傛偦 8 Mbps 偱偡丅偟偟 ATM 僱僢僩R〖僋偼 3.5 Mbps 偱偟鲁傪僒〖僩偟y偣傫丅讳偼僀儞E〖僱僢僩偺柺偱傕偼偢傟偨醡疤栱 偟y偄偡偑丄1,500 僶僀僩偄x峹洐络偒偝偺僷僢僩偱丄RTT 傪巑 250ms 偡傞偺 (3,500,000/8)*.25 = 106KB 偄x僶僢僼傽傪榏擭偡傞涩懨偑偁傝 偟偨(篓郝 128 KB 偱偟偨丅偙傟偱峹洐偱偡)丅

Receive Window 偼 /proc 僼傽僀O僔僗FL偱昛榏擭偱偒偡丅榏擭偟偨偄 僶僢僼傽偺络偒偝偺 2 潬偺栆傪掐蜗偡傞涩懨偑偁傝偡丅

 #echo 262144 > /proc/sys/net/core/rmem_default 
 #echo 262144 > /proc/sys/net/core/rmem_max

湝扺偺焫偩丄湩p偼 128K 偄x栆傪榏擭偟y偄偡丅Send Window 傕偁傢偣y 榏擭偟y偄偡丅偟偟 Send Window 偼 DSL 鲁偍偄y Receive Window 傎偳 椆巢懨朤偼傝偣傫丅

 
 #echo 262144 > /proc/sys/net/core/wmem_default 
 #echo 262144 > /proc/sys/net/core/wmem_max

偙傟傜偺栆偼 sysctl 傪鍥偭y傕榏擭偱偒偡丅man 傪y 偔偩偝偄丅

偦偺滳偟y丄僇〖僱O偺僆僾僔儑儞偱a偱偒傞栆偼晍扺偺奶傝偱偡(尐懨傕偺 偩偗偱偡)丅偙傟傛偭y搀傪偓傝偓傝僠儏〖僯儞僌偟偡丅 

# sysctl -a 
net.ipv4.tcp_rfc1337 = 1
net.ipv4.ip_no_pmtu_disc = 0
net.ipv4.tcp_sack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_timestamps = 1

5.1.2. 僀儞EP〖僽

"僀儞EP〖僽"偼丄ADSL 偱 DMT 搀幩规步傪鍥偭偨崤孿扙偄傞 僄Q〖扩偺偟偔傒偱偡丅DMT 偼 ADSL 偺筛洁Ñ偭y偄y丄ADSL 偱庒傃媝偗y鋛@ 偟y偄傞偺悢彋偱偡丅僀儞EP〖僽偼丄DSLAM 湝偱椻偊慹偔奶奡僨〖E傪 僶僢僼傽P儞僌偟丄僄Q〖柠赖傪槰偄偡丅偙偺懹墙偼丄攔櫷偑b玛傪弹偙偟y 偟x傛x丄搉傜违傟偨搀偱润撅骖滹傪寯带偟偡丅晍傝偱偼偙偺僶僢僼傽 偑鲁湝醾浑偱偒偄镍觅变傪弹偙偟y偄偄偡丅偱偡傜偦傟傝 偺搀墒剂偱偁傞傜丄僀儞EP〖僽偼湩剂晹傕儊P僢僩偼偁傝偣傫偟丄 湩p偼鈉涩懨觅偔傞傕偟傟偣傫丅

僀儞EP〖僽偼僷Q儊〖E偱漝腊偱偒丄攔櫷幠壠偑铜骖偟偨傝醾骖偟偨傝 偱偒偡丅攔櫷幠壠偺傎傫偳偼丄僨僼͙O僩偱偼铜骖偟y偄傞傛x偱偡丅 偦x偡傞偙偱搀傪墱擭偝偣丄F僋僯僇Oˇ僒〖僩傊偺攔櫷傪负傜偣傞傜偱偡丅 偟偟丄儐〖僓偡傋y偑丄偦偺沋㑤偭y偄傞偺偱偡丅

搀偑僀儞EP〖僽偟y偄傞偳x傪悷愮偟丄偨偦傟傪湐构偡傞偼 偳x偟偨傜偄偄偺偱偟x乆 办偼丄1 傕偟偔偼 2 N僢僾阾 滦偟y traceroute 傪偗傞 25ms 鈻柒镍刨傜丄僀儞EP〖僽偑醾骖 偭y偄傞Û偊y傎傏慹斒偄偄鍆偄偡丅 偟偟滳偺懨朤丄偨偊U湩p偳偺镍刨偺N僢僾眶偑偁傞偳x偄偭偨偙傕 偁傝偡丅慪碰偺偙傪氹傞偼丄攔櫷幠壠偺巊偔偟偁傝偣傫丅≈Tx 偼敀偟佷偱偟x丅

"FastPath" DMT偼丄"僀儞EP〖僽傪醾骖偡傞" 偙ÎÝ偠罢蹋偱偡丅傝庤偟偡偑丄偙傟偼 ADSL DMT 偺泴傒孿傢偣 偩偗碰y偼傝偡丅

5.2. 榏栱湝偺b玛

戃偑偭偨偔傟偭偨傝丄鲁偑傞偱偱偒偭偨傜丄偙偺僙僋僔儑儞傪 敂傫偱偔偩偝偄丅儌僨L偺艰傝胺偄棱汤崱傪敂傫偱丄儌僨L偺 LED 偑晹傪嶳偟y 偄傞偺傪悷愮偟y偔偩偝偄(儌僨L偺驴偔偼丄乐僆儗儞l办咖偱奺偭y偄傞 偙偱丄戃偟y偄偄偙傪嶳偟y偄偡)丅

5.2.1. 戃偟偄

儌僨L偺戃傪嶳偡 LED 偑涡㑤偭偨偙偑偄丅

5.2.2. 僱僢僩R〖僋ˇ僇〖僪(NIC)偺b玛

偙偙偱b玛Ñ傞_觉偼丄NIC 偑愮媫偱偒偄丄傕偟偔偼儌l儏〖O偑〖僪 偱偒偄丄ifconfig 偑僀儞E僼僃〖僗傪X僢僾偱偒偄n丄 偦偺滳傕傠傕傠偺僄Q〖偮偄y偱偡丅

5.2.3. IP 鲁湝偺b玛

偙偺僙僋僔儑儞偼丄儌僨L偑戃偟丄NIC 偑愮媫偱偒丄悷昛岒偟y偄傞偙傪 悷愮偟y偄y丄偮僋Q僀X儞ˇ僜僼僩C僃X傪僀儞僗僩〖O偟y晹傕僄Q〖偑 嫨y偄偄偺傕傢傜偢丄ISP 傊鲁偑偱偒偄崤孿敂傫偱偔偩偝偄丅 LED 偱湩p儌僨L偺戃偑艰傟y偄傞傪Y晜偟y偔偩偝偄丅IP 鲁偑愞 偟偨偙偼丄ifconfig 偱X僋F傿僽 eth0 僀儞E僼僃〖僗 (傕偟偔偼 PPPoX 扙偺 ppp0 僀儞E僼僃〖僗)偑嶳绩偝傟偄偙偱傢傝偡丅 傕偟偔偼丄ping 傪僎〖僩C僃僀傗晹虑偮丄 'network unreachable' 傗击偨傛x儊僢僙〖l傪嶳绩 偟偡丅

5.3. 戃湝偺b玛

偙偺僙僋僔儑儞偼丄鲁偼x偔偄偭偨傕偺偺戃偑傟偭偨傝丄戃偑 们鲁猁傟偨傝丄戃庐刨偑澶偟偔屺偪y偟偭偨傝丄"戃偼偟y偄傞偑 僀儞E〖僱僢僩傪扙偱偒偭偨傝"丄偄偭偨崤孿敂傫偱偔偩偝偄丅 (岝櫜儌僨L偱偁傟U丄戃庐刨傪绩偡懹墙傪积偭y偄偡偟丄鋛奶偼 telnet 傗 Web 僽QC僓傪鍥偭y悷愮偱偒偡丅儅僯儏XO傪y偔偩偝偄)丅

戃偑猁傟傞晬Y偼 DSLAM 搀(吗柒殅傕)傕偟偔偼儌僨Lb玛偑偁傞崤孿 寯栏偟偡丅DSLAM 偼办"僇〖僪"傪檾眶偺"僗僢僩 "掐傟傞傛x㑤偭y偄偡丅偨偊U丄Alcatel DSLAM 僇〖僪偼僇〖僪 Q疤鲁傪 4 搀偱偒傞傛x㑤偭y偄偡丅僇〖僪偑偍偟偔傞 R络 4 儐〖僓偑幥巢傪幥傝偡丅僀儞僩偼丄戃偑猁傟傞娞俱偑润撅嘎傜傟偨 认骐偺傕偺偱偁傞偙偱偡丅媩认骐儐〖僓㏸读偑嫨傞僱僢僩R〖僋俱巢偼 樝傝偡丅戃偺b玛偼攔櫷幠壠偺b玛偱偁傝丄ISP 偼馄斊偁傝偣傫丅 僒〖J僗杊銩傪 ISP 冯傫偱偄傞傜丄攔櫷幠壠僐儞E僋僩偑艰傟傞 ISP 偺么碰荚僐儞E僋僩傪偭y偔偩偝偄丅 ≮忦灭丯 DSLAM 偺僇〖僪偼丄偙傫 朩 偱偡≯

戃庐刨偑你晍偟偨傝丄DSL 偺奡规偑猁们偟偨傝偡傞〖僗偼丄撛乿b玛傪錃偒 弹偙偟偡丅偦偺傛x觉轮偱偼R岝庐刨傪评傞偙偼偳x傗偭y傕醾偱偟x丅 偟偟偦偺_觉偑极洐娄偺b玛偺丄僾僶僀僟娄偺丄偼偭偒傝偟y偄傞 傢偗偱偼偁傝偣傫丅

偨偊U丄吗柒偺嬟ў鲁偑偄偄偘傫傜僷僢僩偑屺偪y偟偄丄峗棳偑弹偙偭y 偟偄偡丅偙x傞湩p僗O〖僾僢僩偑屺偪丄鲁偑你晍偟y偟偄偡丅 偙傟偼僱僢僩R〖僋偺b玛偟y骄V傜赂哼偟y偄傞僷僢僩ˇ僗Û偊偑偪 偱偡偑丄DSL 偍偄y偼搀鈉傗奡规负筷丄傕偟偔偼儌僨L极挛偺b玛傛偭y 弹偙傞嵽墙漟偑偁傝偡丅

妶偟y傒偨悢偑偄偄偙傪偄偔偮丅

夺醡偁傞 AM Ql僆搉傗鈉彋X儅僠儏X醾傪偟y偄傞傕偺傕击偨傛x R侨眶傪胺偭y偄傞偺偱丄奦读傪减偗傞偙偑偊傜傟偡丅办媰偺柒偱傕 偁傞搀眶偩偗b玛傪弹偙偡崤孿偑偁傝偡丅偨偊U搉偑屉㑤偭y嫨蜗傪湝偘偨傝 偡傞崤孿偳偑偊傜傟偡丅DSL 摌鈡偑掚傟偨攔櫷幠壠傜丄偙偺b玛傪R堜嘎 偡傞偙偑偱偒傞鍆偄偡丅〖僗僶僀〖僗偱偡偑丅

5.4. 僱僢僩R〖僋僗O〖僾僢僩偺b玛

偙偺僙僋僔儑儞偼鲁偼偱偒y偄傞偑丄僗O〖僾僢僩偑嫨偄b玛傪竖偊y偄傞 崤孿敂傫偱偔偩偝偄丅偮傝杊銩偟y偄傞J僢僩儗〖僩滦偟y丄偦傟 孿偭偨僗O〖僾僢僩偑嫨y偄偄崤孿傗攔櫷搉傜偺调违偑偁傞崤孿碰y偼 傝偡丅偙偙偱偄x"僱僢僩R〖僋"偼丄WAN 傪夞偟偡〗ISP 偺僎〖僩C僃僀Ø〖僇O偺僒僽僱僢僩傕偟偔偼僶僢僋儃〖儞n偺慹傪夞偟偡丅 嘎肠夺偄搀偼戃庐刨偑屺偪y偟x偙傪傟偄偱偔偩偝偄丅偙傟偼 僗O〖僾僢僩傕读傪涂偊偡丅湝扺傪y 偔偩偝偄丅

"觅变""僷僢僩ˇ僗"偑椧偟滇{y偄傞 2 偮偺 懨朤偱偡丅堁荚傕 ping 傗 traceroute 偄偭偨筛洁鍥傢傟傞僱僢僩R〖僋ˇH〖O傪鍥偊U傝词Q纷卢偱偒偡丅 偳偪傜偑搀湝偱弹偙偭偨偟y傕丅僷僼〖儅儞僗㏸读傪涂偊偡丅觅变偼 "瓤鄗偺楁偝"傗"偪枼慹"傪罢蹋偟偡丅晬湩偼丄 O旣觅变偑弹偙偭y偄傞崤孿E〖僎僢僩傪碰y偡丅 偄x偺傕丄驴寈偺觅变偼撅赂哼偟y偄傞傜偱偡丅僷僢僩ˇ僗偼丄椝缄 毗洎偡傞偱偺偳偙偱僷僢僩偺僨〖E偑屺偪y偟x偙偱偡丅TCP/IP 偼 僷僢僩偑"屺偪偨"偙偑傢傞丄屺偪偨僨〖E傪峗棳偟偡丅 偙傟偑弹偙傟U丄湩p汤傜觅偔偭y偟偄偡丅僷僢僩ˇ僗偼鳞 偼 0 % 偱偁傞偼偢偱偡丅

媰撅鍥偭y偄傞 WAN 娄偺暒烯偼丄媟懨偱偁傞偒偪傫愮媫偡傞涩懨偑偁傝偡丅 traceroute 傪樝傞僒僀僩偺偄偔偮偗y傒傟U丄偼偠{偺眶"N僢僾 "偼偠傛x偱偁傞偙偑傢傞鍆偄偡丅偙傟偑 ISP 偺〖僇O 僶僢僋儃〖儞偱偁傝丄偦偺 ISP 偺湝堔僾僶僀僟傊偺僎〖僩C僃僀偱偡丅 偙偺凤偮偄y偺b玛偑晹偱偁傟丄偳偺僒僀僩滦偟y傕丄晹傪偁偨偑偟傛x 偟y傕丄偡傋y读傪减偗y偟偄偡丅

僷僢僩ˇ僗觅变偮偄y偼丄偢 ping 傪 2丄3 舱醡滦偟y槰偭y 傒偟x丅嵽墙傜寈偔傕樝傞 2丄3 舱醡丅偦x偡傟U丄僷僢僩ˇ 僗傗恳撅偱偄O旣觅变偑偮傞鍆偄偡丅 

 $ ping -c 12 -n www.linuxdoc.org
 PING www.linuxdoc.org (152.19.254.81) : 56(84) bytes of data.
 64 bytes from 152.19.254.81: icmp_seq=0 ttl=242 time=62.1 ms
 64 bytes from 152.19.254.81: icmp_seq=1 ttl=242 time=60.8 ms
 64 bytes from 152.19.254.81: icmp_seq=2 ttl=242 time=59.9 ms
 64 bytes from 152.19.254.81: icmp_seq=3 ttl=242 time=61.8 ms
 64 bytes from 152.19.254.81: icmp_seq=4 ttl=242 time=64.1 ms
 64 bytes from 152.19.254.81: icmp_seq=5 ttl=242 time=62.8 ms
 64 bytes from 152.19.254.81: icmp_seq=6 ttl=242 time=62.6 ms
 64 bytes from 152.19.254.81: icmp_seq=7 ttl=242 time=60.3 ms
 64 bytes from 152.19.254.81: icmp_seq=8 ttl=242 time=61.1 ms
 64 bytes from 152.19.254.81: icmp_seq=9 ttl=242 time=60.9 ms
 64 bytes from 152.19.254.81: icmp_seq=10 ttl=242 time=62.4 ms
 64 bytes from 152.19.254.81: icmp_seq=11 ttl=242 time=63.0 ms
 
 --- www.linuxdoc.org ping statistics ---
 12 packets transmitted, 12 packets received, 0% packet loss
 round-trip min/avg/max = 59.9/61.8/64.1 ms

湝扺偼b玛偑偄丄偛偔鋛奶偺焫偱偡(偙偺僒僀僩傊偺暒烯偼丄偁偨偺崤孿偼 湗傜偔偭偨偔樝傞偱偟x丅偟偨偑偭y冯滹傕偭偨偔樝偭y偄傞傕 偟傟偣傫)丅 觅偔傞傛x峫偱椼哼b玛偼偭偨偔偁傝偣傫丅晍扺偺焫偼b玛偑暍澶 偱偡丅 

 $ ping -c 20 -n www.debian.org
 
 PING www.debian.org (198.186.203.20) : 56(84) bytes of data.
 64 bytes from 198.186.203.20: icmp_seq=0 ttl=241 time=404.9 ms
 64 bytes from 198.186.203.20: icmp_seq=1 ttl=241 time=394.9 ms
 64 bytes from 198.186.203.20: icmp_seq=2 ttl=241 time=402.1 ms
 64 bytes from 198.186.203.20: icmp_seq=4 ttl=241 time=2870.3 ms
 64 bytes from 198.186.203.20: icmp_seq=7 ttl=241 time=126.9 ms
 64 bytes from 198.186.203.20: icmp_seq=12 ttl=241 time=88.3 ms
 64 bytes from 198.186.203.20: icmp_seq=13 ttl=241 time=87.9 ms
 64 bytes from 198.186.203.20: icmp_seq=14 ttl=241 time=87.7 ms
 64 bytes from 198.186.203.20: icmp_seq=15 ttl=241 time=85.0 ms
 64 bytes from 198.186.203.20: icmp_seq=16 ttl=241 time=84.5 ms
 64 bytes from 198.186.203.20: icmp_seq=17 ttl=241 time=90.7 ms
 64 bytes from 198.186.203.20: icmp_seq=18 ttl=241 time=87.3 ms
 64 bytes from 198.186.203.20: icmp_seq=19 ttl=241 time=87.6 ms
 
 --- www.debian.org ping statistics ---
 20 packets transmitted, 13 packets received, 35% packet loss
 round-trip min/avg/max = 84.5/376.7/2870.3 ms

僷僢僩ˇ僗偑 35 % 傕偁傝偡丅偨QC儞僪僩P僢僾ˇE僀L傕撛 觅偔偭y偄偡丅偙偺焫傪偪偭漝傋傞傢傞傛x丄b玛Ñ傞僒僀僩 傊偺暒烯湝偼僶僢僋儃〖儞偺O〖E〖偑 13 夵偁傝偡丅偙傟偑晅朤偱偙偺僒僀僩 偑觅偔偭y偄偡偑丄偨偨偠傛xO〖E〖碰偨偭y偟偭偨崤孿偩偗丄 暒烯㏸读偑嫨偡丅慪碰b玛偺偼丄偄偮傕奶檈偡傞O〖E〖偱撛b玛偑 寯栏偟y偄傞偳x偄xY偱偡丅偙偺僎〖僩C僃僀傗 2 廭誊偺O〖E〖傕偦x 傕偟傟偣傫丅Q儞僟L僒僀僩傪联傫偱丄traceroute 傪鍥偭y偮偗嫨偟y偔偩偝偄丅 

 $ traceroute www.bellsouth.net
 
 traceroute to bellsouth.net (192.223.22.134), 30 hops max, 38 byte packets
  1  adsl-78-196-1.sdf.bellsouth.net (216.78.196.1)  14.86ms  7.96ms 12.59ms
  2  205.152.133.65 (205.152.133.65)                  7.90ms  8.12ms  7.73ms
  3  205.152.133.248 (205.152.133.248)                8.99ms  8.52ms  8.17ms
  4  Hssi4-1-0.GW1.IND1.ALTER.NET (157.130.100.153)  11.36ms 11.48ms 11.72ms
  5  125.ATM3-0.XR2.CHI4.ALTER.NET (146.188.208.106) 14.46ms 14.23ms 14.40ms
  6  194.at-1-0-0.TR2.CHI2.ALTER.NET (152.63.65.66)  16.48ms 15.69ms 16.37ms
  7  126.at-5-1-0.TR2.ATL5.ALTER.NET (152.63.0.213)  65.66ms 66.18ms 66.39ms
  8  296.ATM6-0.XR2.ATL1.ALTER.NET (152.63.81.37)    66.86ms 66.42ms 66.40ms
  9  194.ATM8-0.GW1.ATL3.ALTER.NET (146.188.233.53)  67.87ms 68.69ms 69.63ms
 10  IMVI-gw.customer.ALTER.NET (157.130.69.202)     69.88ms 69.25ms 69.35ms
 11  www.bellsouth.net (192.223.22.134)              68.74ms 69.06ms 68.05ms

R偺N僢僾偼僎〖僩C僃僀偱偡丅湩p偼Rǘ傜 2 N僢僾偼撅 偠偱丄Rǘ傜 3丄4 N僢僾偼偨偄y偄偠偱偡丅偮傝丄偳偺 b玛偱偁偭y傕丄偳偙傪憉傟偨偟y傕b玛偑弹偙傝评偡(偁偨极偺泼擭 偺b玛偼偙偺焫偼驴寈斒偭y偄傞傕偟傟偣傫)丅"奶撅偺" 僎〖僩C僃僀傊偺 ping 偼丄晍扺偺奶傝偱偡(讳偭y偼偙傟偑鋛奶偱偡—)丅 

 
 $ ping -c 12 -n 216.78.196.1
 
 PING 216.78.196.1 (216.78.196.1) : 56(84) bytes of data.
 64 bytes from 216.78.196.1: icmp_seq=0 ttl=64 time=14.6 ms
 64 bytes from 216.78.196.1: icmp_seq=1 ttl=64 time=15.4 ms
 64 bytes from 216.78.196.1: icmp_seq=2 ttl=64 time=15.0 ms
 64 bytes from 216.78.196.1: icmp_seq=3 ttl=64 time=15.2 ms
 64 bytes from 216.78.196.1: icmp_seq=4 ttl=64 time=14.9 ms
 64 bytes from 216.78.196.1: icmp_seq=5 ttl=64 time=15.3 ms
 64 bytes from 216.78.196.1: icmp_seq=6 ttl=64 time=15.4 ms
 64 bytes from 216.78.196.1: icmp_seq=7 ttl=64 time=15.0 ms
 64 bytes from 216.78.196.1: icmp_seq=8 ttl=64 time=14.7 ms
 64 bytes from 216.78.196.1: icmp_seq=9 ttl=64 time=14.9 ms
 64 bytes from 216.78.196.1: icmp_seq=10 ttl=64 time=16.2 ms
 64 bytes from 216.78.196.1: icmp_seq=11 ttl=64 time=14.8 ms

 --- 216.78.196.1 ping statistics ---
 12 packets transmitted, 12 packets received, 0% packet loss
 round-trip min/avg/max = 14.6/15.1/16.2 ms

斒x媰弹偙偭偨偠僎〖僩C僄傿偱偺b玛偼晍扺偺奶傝偱偡丅 

 $ ping  -c 12 -n 216.78.196.1
 
 PING 216.78.196.1 (216.78.196.1) : 56(84) bytes of data.
 64 bytes from 216.78.196.1: icmp_seq=0 ttl=64 time=20.5 ms
 64 bytes from 216.78.196.1: icmp_seq=3 ttl=64 time=22.0 ms
 64 bytes from 216.78.196.1: icmp_seq=4 ttl=64 time=21.8 ms
 64 bytes from 216.78.196.1: icmp_seq=6 ttl=64 time=32.0 ms
 64 bytes from 216.78.196.1: icmp_seq=8 ttl=64 time=21.7 ms
 64 bytes from 216.78.196.1: icmp_seq=9 ttl=64 time=42.0 ms
 64 bytes from 216.78.196.1: icmp_seq=10 ttl=64 time=26.8 ms
 
 --- adsl-78-196-1.sdf.bellsouth.net ping statistics ---
 12 packets transmitted, 7 packets received, 41% packet loss
 round-trip min/avg/max = 20.5/25.6/42.0 ms

41 % 偺僷僢僩ˇ僗偼丄润撅岝偄栆偱丄HTTP 偺傛x僒〖J僗傪 偨偔偝傫湝偘y偄傞偙傠偱偼丄樆脸屺偪y偟偄偡丅僒〖J僗偑昛偄y偄偨 偟y傕丄y傕觅偔傝偡丅

湩p弹偙偭偨偙偺焫傪傞丄僎〖僩C僃僀偺漝奃偑奦偄偺偩Î鍆偄偨偔傝偡丅 偟偟傆偨傪樼偗y傞丄攔櫷幠壠偺僱僢僩R〖僋偺 DSLAM ATM 婶洐b玛偑 偁傝偟偨丅偟偨偑偭y僷僢僩ˇ僗傗络偒觅变偑傕x 1 N僢僾誊偺b玛偼丄 湩p偼R偺N僢僾偨偳傝缅偔鈻涟寯栏偟y傞崤孿偑偁傝偊偡丅偙偺b玛傪 猁傝洐偗傞偺舔堃偮H〖O偼偁傝偣傫丅僷僢僩ˇ僗偼 ISP 傗 NSP Ý撛丄 攔櫷幠壠偺b玛偱傕偁傝评偡丅

偨儌僨L极偑僷僢僩ˇ僗傪弹偙偡嵽墙漟傕峹洐偁傝评偡丅偙偺崤孿偼丄 儌僨L偺攔傪掐傟栘偟y丄DSL 偺鲁傪 30 H镍屺偟y傜峗戃偟y傒y 偔偩偝偄丅偮傝鲁湝偁傞偳偺崤醡〗儌僨L傗 DSLAM丄ATM 僱僢僩R〖僋〗 偱偁偭y傕僷僢僩ˇ僗偼弹偙傝评偡丅

ISP 湝偺僱僢僩R〖僋b玛傪寯偟偨傜丄F僋僯僇Oˇ僒〖僩b玛Y傪 憀宩偟y偔偩偝偄丅

5.4.1. 偦偺滳偺僱僢僩R〖僋湝偺b玛

壴驴偙傪偄偔偮丅

5.5. 僗O〖僾僢僩偺纷卢

嵆乿偑偢偼偠{偡傞F僗僩偺 1 偮庐刨纷卢偑偁傝偡丅偙傟傛偭y丄鳞 偟y偄偨傛傝偨偄偟偨偙偑偄偺丄僔僗FL偑峌漝偺傪悷愮偱偒偡丅 赖悷纷卢偡傞偺偼鍆偭偨傎偳傗偝偟偔偼偁傝偣傫丅偢丄僱僢僩R〖僋偱鍥扙 偡傞僾僩僐O偺僆〖僶〖僿僢僪偱丄10 傜 20 % 嫚栆傛傝觅偔傝偡丅 慪碰偳偺偔傜偄"觅偔傞"偼丄僾僶僀僟偺僱僢僩R〖僋麞歨 傛偭y樝傝偡丅偳偙偱丄偳偺傛x栆傪纷偭偨攂赂偟偡丅鋛奶偼丄10 20 % 傜偄㑤傝偡丅

僀儞E〖僱僢僩X僋僙僗偡傞丄N僢僾偑笼偊傞偛Ò傢偢偱偡偑僷僼〖儅儞僗 偑你晍偟y偄偡丅晬觉偦傟镍络偒读偼偄鍆偄偡丅统偼N僢僾眶偑 偦傟镍偱傕偭偨傝丄僐儞僺儏〖E偡傋y〗偁偨偺僔僗FL傗 ISP 偺僱僢僩 R〖僋丄湝堔偺 ISP 偺僾僶僀僟丄偦偟y鲁椝缄〗偑偡傋y缄掐傟偺槰偒晵偄偨 懹忢Ý偠傛x丄晹偺毁俱傕偔昛偄y偄偨傝偡傞嘎傝偼丅偟偟丄俱巢偑偁傟U 〗偦偺懨朤偑傣媟傕泴傒孿傢偝偭y偄傞偙傪丄偳x傗偭y娣偱偒傞偱偟x乆 暒烯湝偺O〖E偺偳傟刁昛鈉砍偺僀儞E僼僃〖僗偑 1 偮偱傕偁傟U丄疙偭偨冯滹 㑤偭y偟x傕偟傟偣傫丅

悷湩R络庐刨偑嫨傞偱偁傠x鲁阾偼丄嵸掐偟y偄傞 ISP〗ISP 偺僎〖僩C僃僀 偱偡丅偦偙傊办扥晍傟U偄偄偩偗偱丄敾傞偙偼偄傜偱偡丅 偮傝鳞F僗僩偼丄偱偒傞偩偗极吗傜夺偄偙傠偱偡丅 偙傟偼嵽墙嘎傝鳞偱偒偄懨朤偺眶乿傪艰傝嬤偗傞傜偱偡丅ISP 〖僇O 偺 ftp 僒〖僶偑偁傞傜丄F僗僩傪槰x椻峌偺崤醡㑤傝偡(traceroute 傪偗y丄慪碰〖僇O偺傪y偔偩偄)丅

ISP 偑 ftp 僒〖僶傪积偭y偄偄傜丄夺偔偁傞 ftp 僒僀僩傪玫偟y偔偩偝偄〗 N僢僾眶偑偱偒傞偩偗寈偄悢偑峌偟偄偱偡丅偨嵷僒〖僶傪偮偗y偔偩偝偄丅 偱偄偍偟冯滹㑤偭y偟偄偡丅络偒僼傽僀O傪偮偗y〗 10 MB 镍刨〗丄僟C儞〖僪枼慹傪纷偭y偔偩偝偄丅偙傟傪晹媰鲁偗y傒y偔偩偝偄丅 偨丄帢乿偺枼偱湩槰偟y傒y偔偩偝偄丅僒〖僶傗僶僢僋儃〖儞偼丄1 媰偺柺偱 偁傞枼g偟偄崤孿偑偁傝偡偺偱丅偙x偟偄丄冯滹偑偑傒丄搑纷懨朤傪 偱偒傞偩偗嫰嬤偡傞涩懨偑偱y偔傞傜偱偡丅僾僶僀僟偼丄僶僢僋儃〖儞偺 僩Q僼傿僢僋偑媟偄偙傗儃僩O僱僢僋丄觅偔y砷偑媟偄僒〖僶n滦偟y偼 瘦偟y偄偣傫丅

F僗僩偡傞僒僀僩偑偁偪偙偪欢哼偟y偄偡丅偄偙傠傕偁傝偡偑丄櫷洐 偟y偍偄y偔偩偝偄丅偁傝傕懨朤偑偨偔偝傫偁傞偨{丄F僗僩傛傞鲁傗 僗O〖僾僢僩偺偦偺崤偺纷卢栆偼赖悷偱偁傞偼T偊偣傫丅偙傟傜偺僒僀僩偱偼丄 偁偨偑偦x偁傞傋偒偩鍆偭y偄傞栆偺钓悇认骐偁傞丄偄偄偄x车懨 傪偮傓傜偄偼偱偒傞傕偟傟偣傫丅庐刨F僗僩偟y偍{偼丄http://www.dslreports.com/stest/0 http://speedtest.mybc.com/ 偑偁傝偡(堁悢傕 Java 偑涩懨偱偡)丅滳偺僒僀僩偺冯滹傛傝偼赖悷 偩鍆偄偡丅

偙偙偱傟y偼偄偗偄偺偼丄偍傛偦 10 % 20 % 偺僱僢僩R〖僋 湝偺僆〖僶〖僿僢僪偄x扩銩傪减偗傞偙偱偡丅焫傪湝偘y偍偒偡丅讳偺崤孿 偼丄1472 Kbps 偄x戃庐刨偑湝嘎偱偡丅偙偙傜偍傛偦 15 % 屺偪傞 1275 Kbps Ñ傝偡丅偙偺戃庐刨偼丄攔櫷搉傜 11,000 僼傿〖僩(銩 3,350 m) 偁傞偙傪偊傞峹洐庐刨偱丄湩p偼 1275 Kbps 偮傝偍偍傛偦 1.2 1.3 Mbps 偄x丄R络嘎偺僗O〖僾僢僩偑嫨y偄傞ÉT偭y傕偄偄鍆偄偡 〗滳偺孈凤偑偠傜U偱偡偑丅dslreports.com 偺庐刨F僗僩偼晍扺偺奶傝偱偡丅

 Test running..Downloaded 60900bytes in 5918ms
 Downloaded 696000bytes in 4914ms
 First guess is 1133kbps
 fairly fast line - now test 2mb
 Downloaded 1679100bytes in 11090ms
 Upload got ok 1 bytes uploaded
 Uploaded 1bytes in 211ms
 Upload got ok 1 bytes uploaded
 Uploaded 1bytes in 205ms
 Upload got ok 1 bytes uploaded
 Uploaded 1bytes in 207ms
 Upload got ok 50000 bytes uploaded
 Uploaded 50000bytes in 2065ms
 Upload got ok 100000 bytes uploaded
 Uploaded 100000bytes in 3911ms
 
 ** Speed 1211(down)/215(up) kbps **
 (At least 24 times faster than a 56k modem)
 Finish.

1.211 Mbps 偄x栆偼丄僒〖J僗滦偟y晬湩戃偟y偄偨栆傎傏偠偱偡丅 偙偺冯滹滦偟y丄僩Q僽O僔儏〖F傿儞僌傗僠儏〖僯儞僌悢彋傪玫偟嫨偡扥偼偁傝 偣傫丅

暟宩———丯讳偑嵸掐偟y偄傞 ISP 偼 Web M〖l扙 @儍僢僔儏ˇ僾僋僔傪堃yy偄偡丅偙傟偼偙偺缄偺 Web V〖僗偺F僗僩偺冯滹 傪傜偟y偟偄偡丅傕偟偙傟偑偗傟U丄F僗僩偺冯滹偼汤傜觅偔偭y 偟偭偨偱偟x丅僾僋僔偑偁傞丄湩p偼僾僋僔傜偺僗O〖僾僢僩 傪F僗僩偟y偄傞偙Ò㑤偭y偟偄偡〗F僗僩僒僀僩偱偼偔丅渏偱丄 帢偺暟宩傪丅枼帢偺F僗僩僒僀僩傪纷卢偟偟偨偑丄 600 700 Kbps 偑僐儞僗E儞僩嫨偟偨丅偁丄〖僗僶僀〖僗偱偡偑(偄偮傕偼丄驴傟 寈傟丄偦傟偧傟偠傛x冯滹偑嫨y偄偡)丅2 偮偺樝傞僒僀僩傜络偒 僼傽僀O傪 ftp 偟y纷卢偟y偔偩偝偄丅讳偺崤孿偼丄銩 1.25 Mbps 偱偟偨丅

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墱链鲁傪偡傞 烧嫭: DSL 偺车维