Depends on the setup. With MPLS and traffic engineering tunnels you can make a 30 hop path look like one hop easily.
On 8/13/14, 9:25 AM, "Martin T" <m4rtn...@gmail.com> wrote: >Hi, > >if I make a traceroute to a host in San Jose in Level3 network from >DigitalOcean server in Amsterdam, then in Level3 network(hop 6 in >example below) the RTT remains the same: > ># traceroute -q 1 -I ZYNGA-INC.edge1.SanJose3.Level3.net >traceroute to ZYNGA-INC.edge1.SanJose3.Level3.net (4.53.208.114), 30 >hops max, 60 byte packets > 1 5.101.103.253 (5.101.103.253) 0.265 ms > 2 95.85.0.229 (95.85.0.229) 0.236 ms > 3 ix-4-2-0-0.tcore1.AV2-Amsterdam.as6453.net (195.219.194.25) 0.275 ms > 4 if-7-2.tcore1.AD1-Amsterdam.as6453.net (195.219.194.46) 0.630 ms > 5 4.68.63.41 (4.68.63.41) 0.635 ms > 6 vl-3603-ve-227.csw2.Amsterdam1.Level3.net (4.69.162.153) 155.309 ms > 7 ae-56-221.ebr2.Amsterdam1.Level3.net (4.69.153.201) 155.627 ms > 8 ae-46-46.ebr2.London1.Level3.net (4.69.143.74) 153.470 ms > 9 * >10 ae-61-61.csw1.NewYork1.Level3.net (4.69.134.66) 148.972 ms >11 * >12 ae-2-2.ebr1.SanJose1.Level3.net (4.69.135.185) 147.881 ms >13 ae-91-91.csw4.SanJose1.Level3.net (4.69.153.14) 149.632 ms >14 ae-4-90.edge1.SanJose3.Level3.net (4.69.152.208) 151.107 ms >15 ZYNGA-INC.edge1.SanJose3.Level3.net (4.53.208.114) 154.431 ms ># > >In other words, one sees the RTT of the end-host as a RTT for all the >hops in Level3 netwotk. If I make the traceroute to penultimate hop >ae-4-90.edge1.SanJose3.Level3.net, then RTT is as expected: > >root@vserver:~# traceroute -q 1 -I ae-4-90.edge1.SanJose3.Level3.net >traceroute to ae-4-90.edge1.SanJose3.Level3.net (4.69.152.208), 30 >hops max, 60 byte packets > 1 5.101.103.254 (5.101.103.254) 0.228 ms > 2 95.85.0.237 (95.85.0.237) 0.217 ms > 3 ix-4-2-0-0.tcore1.AV2-Amsterdam.as6453.net (195.219.194.25) 0.276 ms > 4 if-7-2.tcore1.AD1-Amsterdam.as6453.net (195.219.194.46) 0.656 ms > 5 4.68.63.41 (4.68.63.41) 0.607 ms > 6 vl-3604-ve-228.csw2.Amsterdam1.Level3.net (4.69.162.157) 0.696 ms > 7 ae-56-221.ebr2.Amsterdam1.Level3.net (4.69.153.201) 0.677 ms > 8 ae-45-45.ebr2.London1.Level3.net (4.69.143.70) 7.059 ms > 9 ae-44-44.ebr1.NewYork1.Level3.net (4.69.137.78) 76.311 ms >10 ae-81-81.csw3.NewYork1.Level3.net (4.69.134.74) 76.265 ms >11 ae-82-82.ebr2.NewYork1.Level3.net (4.69.148.41) 76.820 ms >12 ae-2-2.ebr1.SanJose1.Level3.net (4.69.135.185) 149.101 ms >13 ae-91-91.csw4.SanJose1.Level3.net (4.69.153.14) 150.557 ms >14 ae-4-90.edge1.SanJose3.Level3.net (4.69.152.208) 162.022 ms >root@vserver:~# > >All the ICMP "TTL exceeded" messages except the first and the >penultimate one in Level3 network have MPLS extensions >header(s24.postimg.org/4z9at9z45/ICMP_echo_reply_MPLS_extensions.png) >which is always the same except the tag value changes. > >How does this technically work? What are the advantages of such setup? > > >thanks, >Martin