mtr misses last packet in report mode for high latency hops
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
mtr (Ubuntu) |
Confirmed
|
Undecided
|
Unassigned |
Bug Description
mtr always misses the last packet in report mode for high latency last hops and reports that as packet loss.
For example if you are in Europe or USA this can be always reproduced running mtr to host "auspost.com.au" in report mode. If running in non report mode there would be no packet loss reported.
Please see examples below. Note that loss of 50% for the last few hops if the cycle count for mtr is set to 2. If set to 3, the packet loss would always be 33% for those hops, if count is set to 10 - 10% loss and so on.
user@myhostname:~$ mtr --report -n -c 2 auspost.com.au
HOST: myhostname Loss% Snt Last Avg Best Wrst StDev
1.|-- 192.168.0.1 0.0% 2 0.3 0.3 0.3 0.4 0.1
2.|-- ??? 100.0 2 0.0 0.0 0.0 0.0 0.0
3.|-- 213.190.41.21 0.0% 2 0.6 0.7 0.6 0.7 0.1
4.|-- 82.135.182.1 0.0% 2 0.7 0.7 0.7 0.7 0.0
5.|-- 213.248.85.89 0.0% 2 11.5 11.5 11.5 11.5 0.0
6.|-- 80.91.251.35 0.0% 2 26.2 25.8 25.5 26.2 0.5
7.|-- 213.155.131.247 0.0% 2 120.1 120.1 120.1 120.1 0.0
| `|-- 213.155.131.245
8.|-- 213.155.135.157 0.0% 2 197.6 196.0 194.5 197.6 2.2
9.|-- 80.239.167.182 0.0% 2 201.4 200.2 198.9 201.4 1.8
10.|-- 203.208.148.90 50.0% 2 357.5 357.5 357.5 357.5 0.0
11.|-- ??? 100.0 2 0.0 0.0 0.0 0.0 0.0
12.|-- 119.225.138.30 50.0% 2 376.0 376.0 376.0 376.0 0.0
13.|-- 172.16.16.186 50.0% 2 378.9 378.9 378.9 378.9 0.0
14.|-- 172.16.16.92 50.0% 2 384.5 384.5 384.5 384.5 0.0
15.|-- 202.58.62.160 50.0% 2 383.7 383.7 383.7 383.7 0.0
user@myhostname:~$ mtr --report -n -c 3 auspost.com.au
HOST: myhostname Loss% Snt Last Avg Best Wrst StDev
1.|-- 192.168.0.1 0.0% 3 0.3 0.3 0.2 0.5 0.1
2.|-- ??? 100.0 3 0.0 0.0 0.0 0.0 0.0
3.|-- 213.190.41.21 66.7% 3 20.8 20.8 20.8 20.8 0.0
4.|-- 82.135.182.1 0.0% 3 0.6 0.7 0.6 0.8 0.1
5.|-- 213.248.85.89 0.0% 3 11.5 11.5 11.5 11.5 0.0
6.|-- 80.91.251.35 0.0% 3 25.4 39.7 25.4 68.2 24.7
7.|-- 213.155.131.247 0.0% 3 199.6 181.0 120.1 223.3 54.1
8.|-- 80.91.248.188 0.0% 3 194.4 194.0 193.0 194.5 0.9
| `|-- 213.155.135.157
9.|-- 195.12.255.234 0.0% 3 198.9 197.2 193.9 198.9 2.9
| `|-- 80.239.167.182
10.|-- 203.208.148.90 0.0% 3 358.2 358.0 357.6 358.3 0.4
11.|-- ??? 100.0 3 0.0 0.0 0.0 0.0 0.0
12.|-- 119.225.138.30 33.3% 3 377.2 376.6 376.0 377.2 0.9
13.|-- 172.16.16.186 33.3% 3 378.2 380.1 378.2 382.0 2.7
14.|-- 172.16.16.92 33.3% 3 384.2 384.2 384.2 384.3 0.0
15.|-- 202.58.62.160 33.3% 3 384.5 383.1 381.7 384.5 2.0
user@myhostname:~$ mtr --report -n -c 10 auspost.com.au
HOST: myhostname Loss% Snt Last Avg Best Wrst StDev
1.|-- 192.168.0.1 0.0% 10 0.3 0.3 0.2 0.4 0.0
2.|-- ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
3.|-- 213.190.41.21 20.0% 10 0.6 4.6 0.6 29.2 10.0
4.|-- 82.135.182.1 0.0% 10 0.7 1.8 0.6 11.8 3.5
5.|-- 213.248.85.89 0.0% 10 11.4 15.5 11.4 48.0 11.5
6.|-- 80.91.251.35 0.0% 10 25.4 37.4 25.3 111.9 27.7
7.|-- 213.155.131.245 0.0% 10 165.0 131.9 120.0 165.0 19.2
| `|-- 213.155.131.247
8.|-- 213.155.135.157 0.0% 10 194.4 197.0 192.9 223.7 9.4
| `|-- 80.91.248.188
9.|-- 80.239.167.182 0.0% 10 193.9 206.1 193.9 278.6 25.7
| `|-- 195.12.255.234
10.|-- 203.208.148.90 0.0% 10 358.0 357.7 357.5 358.1 0.2
11.|-- ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
12.|-- 119.225.138.30 10.0% 10 375.9 376.5 375.9 379.1 1.0
13.|-- 172.16.16.186 10.0% 10 378.8 378.6 378.2 379.1 0.4
14.|-- 172.16.16.92 10.0% 10 384.3 384.6 384.2 385.2 0.4
15.|-- 202.58.62.160 10.0% 10 383.5 381.4 378.4 383.5 2.1
It seems that this bug was already fixed in version 0.81 of mtr (see link below), but the fix was not integrated into ubuntu package. I tested mtr on 3 different machines running Ubuntu Oneiric and Natty and in all cases this problem was present. Also it seems this will be affecting Ubuntu 12.04 Precise Pangolin
https:/ /bugs.launchpad .net/mtr/ +bug/776211