[zeromq-dev] SOLUTION-- Encryption failure problem and wireless connectivity

James Chapman james at linux-101.org
Fri Dec 19 16:36:42 CET 2014


>
> I don't mean this to be condescending in anyway and if you already know
> this then feel free to ignore it. It's just a common misconception about
> traceroute and packet loss.



> Please don't rely on MTR and other traceroute type utilities to diagnose
> packet loss.


These tools work by sending packets to a destination with a TTL of, 1 then
2 then 3 and so on. Each router along the path subtracts 1 from the TTL.
When the TTL hits 0 the router responds with TTL exceeded. Routers will
typically rate limit ICMP generation (your traceroute reply) and if it
happens to be very busy it simply might not respond and to you it will
appear as though a packet has been dropped. This is normal and is in fact
NOT packet loss.

To correctly identify packet loss you need to be looking at the loss
against the endpoint and not the intermediaries. When you send 100 ping
packets to the destination do you get 100 replies? Do you see packet loss
using something like "echoping"?

Further traceroute reading:
A practical guide to (correctly) troubleshooting with Traceroute
https://www.nanog.org/meetings/nanog45/presentations/Sunday/RAS_traceroute_N45.pdf


James
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