Traceroute results ...

[InternetB]

Hi,

[1] I would like to know if a traceroute results are accumulative, meaning the last hope is the total round trip time ?

H:\>tracert -d 1.1.1.1

Tracing route to 145.16.28.130 over a maximum of 30 hops

1 <1 ms <1 ms <1 ms 2.2.2.2

2 <1 ms <1 ms <1 ms 3.3.3.3

3 2 ms 1 ms 1 ms 4.4.4.4

4 241 ms 240 ms 239 ms 5.5.5.5

5 241 ms 234 ms 234 ms 6.6.6.6

6 236 ms 250 ms 238 ms 7.7.7.7

7 236 ms 238 ms 235 ms 8.8.8.8

Thank you,

- InternetB-

[crow930us]

Each packet coming back lists the results from that specific router. So the results from the 6.6.6.6 address are for the time it takes to travel between that point and you.

[InternetB]

Hi,

If that is the case, say there is a congestion on the 5th hop

5 241 ms 234 ms 234 ms 6.6.6.6

and say the 6th hop shows something like this

6 10 ms 10 ms 10 ms 7.7.7.7

For the source to reach the 6th hop, it has to traverse the 5th hop which is having latency. So how would it be possible to make a round trip of 10ms to reach back the source ip if it has to pass the 5th hop which takes

234 ms ?

* (I made the figures up here but have seen scenario's like this in real life.)

Thank you,

Cheers,

- InternetB -

[tcordier]

The router sends 3 packets to the destination with a TTL of 1, and records the response time using the timesstamps of the "ICMP Time Exceeded" packets it receives back. Then the routers sends another 3 packets to the destination, now with a TTL of 2, and again calculates the response times, and so forth. This means that normally, the response time for hop 6 is higher than the response time for hop 5, but it does not need to be. It could be that there was a network event (utilization or routing problems) delaying the packets when travelling back and forth to hop 5, and the same event was not present when the packets travelled back and forth to hop 6. In that case you could see better response times for hops further away.

- thomas