traceroute is a mechanism that can be used to find the route IP packets are taking ``from here to there''. Traceroute sends a sequence of packets to the destination. The first three start with TTL = 1, the next three with TTL = 2, etc. At NJIT it is impossible to ``traceroute'' to locations outside NJIT. There are many public sites from which one can do traceroute. For example sdf.lonestar.org . (Telnet in. Login: cis656 . Password: cis656) Otherwise: any of the public traceroute sites listed in http://www.traceroute.org/ Example: --- alizarin-56 ott>: telnet sdf.lonestar.org Trying 207.202.214.132... Connected to sdf.lonestar.org. Escape character is '^]'. sdf.lonestar.org if new, login 'new'.. login: cis656 password: Join ARPA today! Type 'arpa' for more info. Want to host your own domain here? read the 'faq' VHOST Type 'help' for commands /udd/c/cis656> traceroute ftp.nl.net traceroute: Warning: ftp.nl.net has multiple addresses; using 195.129.111.9 traceroute to ftp.eu.uu.net (195.129.111.9), 30 hops max, 52 byte packets 1 gw (207.202.214.129) 1.661 ms 1.667 ms 0.833 ms 2 Serial2-7.GW1.SEA1.ALTER.NET (137.39.136.129) 2.473 ms 1.661 ms 2.479 ms 3 103.ATM3-0.XR1.SEA1.ALTER.NET (146.188.200.42) 3.331 ms 7.498 ms 4.991 ms 4 195.at-1-1-0.TL1.SEA1.ALTER.NET (146.188.200.98) 4.138 ms 1.666 ms 3.298 ms 5 0.so-1-2-0.TL1.DCA6.ALTER.NET (146.188.136.165) 79.167 ms 79.166 ms 79.979 ms 6 0.so-7-0-0.IL1.DCA6.ALTER.NET (152.63.9.193) 79.166 ms 89.162 ms 79.972 ms 7 so-1-0-0.IR1.DCA4.Alter.Net (146.188.13.38) 80.806 ms 82.496 ms 79.996 ms 8 so-5-0-0.TR1.AMS2.Alter.Net (146.188.5.198) 164.984 ms 164.995 ms 165.831 ms 9 so-5-0-0.xr1.ams6.alter.net (146.188.8.77) 203.324 ms 163.336 ms 163.333 ms 10 195.atm6-0-0.hr1.ams6.alter.net (212.136.184.13) 163.332 ms 163.333 ms 195.at-1-0-0.hr1.ams6.alter.net (212.136.184.5) 163.332 ms 11 * * * 12 * * * 13 * * * --- The first 10 routers respond. Then (probably) there is a router that does not pass returning ICMP messages, so it seems that all further routers are dead. (Or maybe 195.129.111.9 does not respond? There may be a firewall). Let's try the other address: --- /udd/c/cis656> traceroute 195.129.111.8 traceroute to 195.129.111.8 (195.129.111.8), 30 hops max, 52 byte packets 1 gw (207.202.214.129) 0.830 ms 0.820 ms 2.483 ms 2 Serial2-7.GW1.SEA1.ALTER.NET (137.39.136.129) 4.996 ms 3.327 ms 1.650 ms 3 103.ATM3-0.XR2.SEA1.ALTER.NET (146.188.200.38) 1.655 ms 2.495 ms 2.483 ms 4 294.at-2-0-0.TL2.SEA1.ALTER.NET (146.188.200.126) 3.313 ms 2.497 ms 3.317 ms 5 0.so-3-0-0.TL2.DCA6.ALTER.NET (152.63.19.170) 80.814 ms 82.492 ms 80.002 ms 6 0.so-7-0-0.IL2.DCA6.ALTER.NET (152.63.9.221) 79.149 ms 79.166 ms 79.166 ms 7 so-0-0-0.IR2.DCA4.Alter.Net (146.188.13.42) 84.146 ms 84.993 ms 79.996 ms 8 so-1-0-0.TR2.AMS2.Alter.Net (146.188.3.106) 176.647 ms 171.660 ms 164.155 ms 9 so-6-0-0.xr2.ams6.alter.net (146.188.8.89) 164.145 ms 173.331 ms 163.334 ms 10 194.atm6-0-0.hr1.ams6.alter.net (212.136.184.9) 164.979 ms 163.337 ms 194.atm1-0-0.hr1.ams6.alter.net (212.136.184.1) 164.143 ms 11 * * * 12 * * * 13 * * * --- Please note that there are many differences in routers and router addresses between the first time and the second time! This probably means that there are ``router banks'' that do load sharing, but of course have their own interfaces. The first time router 8 is so-5-0-0.TR1.AMS2.Alter.Net (146.188.5.198) . The second time router 8 is so-1-0-0.TR2.AMS2.Alter.Net (146.188.3.106) . etc. The first time, the three packets with TTL = 8 are dropped by so-5-0-0.TR1.AMS2.Alter.Net (146.188.5.198), which sends back ICMP error messages (TTL expired). The three RTTs are 164.984 ms 164.995 ms 165.831 ms. (Or maybe only the first of the three packets is returned by that router?). The second time the three packets (or the first of the three?) are returned by so-1-0-0.TR2.AMS2.Alter.Net (146.188.3.106), and the three RTTs are 176.647 ms 171.660 ms 164.155 ms. The problem after router 10 may be something else than a non-responding host, or a router not passing ICMP messages. The output line for the ``router 10'' looks strange, as if there was a response with bad syntax. With ``ping'' from sdf.lonestar.org : --- /udd/c/cis656> ping 195.129.111.8 PING ftp0.svc.ops.eu.uu.net (195.129.111.8): 48 data bytes 64 bytes from 195.129.111.8: icmp_seq=0 ttl=244 time=164.997 ms 64 bytes from 195.129.111.8: icmp_seq=1 ttl=244 time=169.167 ms 64 bytes from 195.129.111.8: icmp_seq=2 ttl=244 time=164.173 ms 64 bytes from 195.129.111.8: icmp_seq=3 ttl=244 time=164.167 ms 64 bytes from 195.129.111.8: icmp_seq=4 ttl=244 time=187.500 ms ----ftp0.svc.ops.eu.uu.net PING Statistics---- 5 packets transmitted, 5 packets received, 0.0% packet loss --- It seems that so-1-0-0.TR2.AMS2.Alter.Net must already be fairly close to ftp.nl.net . However, one must be careful not to overinterprete. Round Trip Times can be notoriously variable. In case of routers, there can be a significant and highly variable additional delay for ``special'' packets that require attention from higher level software.