A Practical Guide to (Correctly)

《A Practical Guide to (Correctly)》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、APracticalGuideto(Correctly)TroubleshootingwithTracerouteCreatedbyRichardASteenbergenPresentedbyDaniRoismanatNANOGontheRoadHonolulu15January2017Introduction•TroubleshootingproblemsontheInternet?•Thenumberonego-totoolis“t

2、raceroute”•EveryOScomeswithatraceroutetoolofsomekind.•Therearethousandsofwebsiteswhichcanrunatraceroute.•Therearedozensof“visualtraceroute”toolsavailable,bothcommerciallyandfree.•Anditseemslikesuchasimpletooltousetoo•TypeinthetargetIPaddress,anditshowsmeev

3、eryrouterhopalongtheway,alongwithalatencymeasurement.•Andwherethetraceroutestops,orwherethelatencyjumpsupalot,that’swheretheproblemis,right?•Howcouldthispossiblygowrong?•Unfortunately,itneverquiteworksthiswayinpractice.ByRichardSteenbergen2Introduction•Sow

4、hatcangowrongwithtraceroute?•Mostmodernnetworksareactuallyprettywellrun•Simpleissueslikecongestionorroutingloopsarebecomingasmallerpercentageofthetotalnetworkissuesencountered•Theremainingissuesarebecomingevermorecomplex,sothatoftenanaïvetracerouteinterpre

5、tationispracticallyuseless•Veryfewpeopleareskilledatinterpretingtraceroute•Tracerouteoutputlooksrelativelystraight-forwardtoreadanduse•Thistendstogivepeopletheimpressionthattheyarequalifiedtointerpretitandlocatethefault,evenwhentheyarenot•InrealitymostISPN

6、OCs,andevenmostmid-levelIPengineeringstaff,arenotqualifiedtocorrectlyinterpretacomplextraceroute•TheresultingswarmofboguscomplaintsmakesitverydifficultforknowledgeablepeopletogettracerouteissueslookedatandfixedByRichardSteenbergen3ExampleTracerouteOutput•I

7、mplementationsvary,butalltraceroutelooksalittlesomethinglikethis:Hop#Router(DNS)Router(IP)LatencyMeasurementsInthisexample,eachrouterhophasthreelatencyprobes:tracerouteto4.2.2.2(4.2.2.2),64hopsmax,52bytepackets1ge0-34.aggrFZ155-2.ord6.us.scnet.net(204.93.1

8、76.73)1.673ms1.187ms2.847ms2ge-9-2-9.ar2.ord6.us.scnet.net(75.102.0.69)0.317ms0.163ms0.155ms372.ae3.cr2.ord6.us.scnet.net(204.93.204.158)0.203ms4as3549.xe-0-2-1.cr2.ord6.us.scnet.net(204.93.144.30)0.929ms0.89