RTT of ICMP "TTL exceeded" messages in Level3 network remains the same throughout the network

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1

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

2

How does this technically work? What are the advantages of such setup?

http://forums.juniper.net/t5/Routing/what-does-quot-icmp-tunneling-quot-mean-in-mpls-vpn/td-p/164284
http://www.juniper.net/techpubs/en_US/junos12.1/topics/usage-guidelines/mpls-configuring-icmp-message-tunneling.html

...and from https://www.nanog.org/meetings/nanog49/presentations/Sunday/mpls-nanog49.pdf:

3

Depends on the setup. With MPLS and traffic engineering tunnels you can
make a 30 hop path look like one hop easily.