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How to interpret an mtr table?
k9banger02
Barred
I am using mtr to diagnose some connectivity issues, using a plain mtr x.x.x.x command.
Do the figures for each line of output refer to the values between it and the line above it, or are they from the source, ie the place you type the command?
In the output below there is a 16.6% loss on line 9 ldn-bb4-link.ip.twelve99.net. Is that loss from the original willie-wanker location or from the previous line 8 nyk-bb1-link.ip.twelve99.net
willie-wanker (173.236.xxx.xxx) 2022-12-08T11:45:42-0800
Keys: Help Display mode Restart statistics Order of fields quit
Packets Pings
Host Loss% Snt Last Avg Best Wrst StDev
1. ip-173-236-224-1.dreamhost.com 0.0% 206 2.2 2.4 1.0 11.2 1.0
2. ip-208-113-156-48.dreamhost.com 0.0% 206 0.3 0.4 0.2 5.6 0.6
3. iad1-bdr-2.sd.dreamhost.com 0.0% 206 0.4 0.9 0.3 15.2 1.7
4. be5698.rcr51.b037327-0.iad02.atlas.cogentco.com 0.0% 206 2.3 0.6 0.5 2.5 0.2
5. be3562.ccr41.iad02.atlas.cogentco.com 0.0% 206 1.0 4.3 0.8 121.4 15.2
6. telia.iad02.atlas.cogentco.com 0.0% 206 1.1 0.9 0.7 2.0 0.2
7. rest-bb1-link.ip.twelve99.net 0.0% 206 1.8 1.9 1.8 3.6 0.2
8. nyk-bb1-link.ip.twelve99.net 0.0% 206 8.2 8.3 8.2 10.4 0.2
9. ldn-bb4-link.ip.twelve99.net 16.6% 205 77.4 78.4 77.2 103.0 3.4
10. ldn-b3-link.ip.twelve99.net 0.0% 205 75.1 75.2 74.9 77.6 0.3
11. clouvider-ic337427-ldn-b3.ip.twelve99-cust.net 0.0% 205 75.5 75.8 75.3 95.8 1.9
12. ???
13. h185-145-200-86.reverse.clouvider.net 0.0% 205 75.6 77.7 75.5 138.1 8.2
14. h185-145-200-87.reverse.clouvider.net 0.0% 205 76.1 85.2 76.0 171.6 13.8
15. 185.145.200.36 0.0% 205 142.9 81.6 75.9 153.9 9.5
16. 185.187.154.10 0.0% 205 76.5 75.8 75.7 79.4 0.4
Comments
All the numbers are ping from your pc/machine where you typed the command.
Above you can see what they mean exactly in the output
Edit:
It is the loss from willie-wanker, but package loss in hops isnt necessarily bad and can just be a firewall rule from that host.
I take it then that between lines 8 - 10 where line 9 has 16.6% packet loss, the router on line 8 must be routing around line 9 for there to be no packet loss on line 10.
No that is not case router 9 just dont answers all your ping (often due to firewall or other security systems). If the 16% loss continued to all the following hops, it would be a problem
TIP: you have hidden your ip addres on top but in the host name it is still visisble
That must be due to multihoming.
That is the gateway
Just want to talk about the packet loss versus ping. If you have a firewall rate limiting the ICMP you will see a considerate amount of loss in the MTR at a specific hop. Take it with a grain of salt and check other variables. Had this happen recently where I was having 90% packet loss at the destination when pinging and after a few minutes noticed it was just CSF rate limiting ICMP. Websites were loading fine. Just something to think about when seeing packet loss.
For mtr I found this Cloudflare article quite useful:
https://www.cloudflare.com/learning/network-layer/what-is-mtr/