offtopic: mtr losing (was Re: where to sync from?)
Rafal Wozniak (debian@rafal.wozniak.name) wrote on 22 March 2007 05:09:
>Wednesday 21 of March 2007 23:36:40 Carlos Carvalho napisaâ(a):
>> I tried mtr for the first time. Nice but not reliable(?!?!). From my
>> machine (not in the same site as the mirror) to our gateway it reports
>> 16-22% of packet loss!! This is nonsense, real packet loss is zero
>> (tried ping -f to confirm).
>
>mtr and ping work diffrent. it is natural that mtr my show same
>losses. it depends what type of router is used. replays for pings
>has a low piority. but important is that on later hops aren't
>losses.
Josip Rodin (joy@entuzijast.net) wrote on 22 March 2007 08:23:
>See, that's where mtr came in handy. You may not have been getting actual
>loss when directing ping packets via ICMP, but the UDP traceroute packets
>with lower priority are getting lost. Packets get lost when the intervening
>routers drop them in order to slow you down. mtr usually helps determine
>which routers do that.
This is unlikely. I tested from my desktop machine. It's connected to
the gateway through two switches. It's not loaded, the switches are
not loaded and the connection between them is gigabit; my machine is
100Mb/s. They're level 2 only, without priorities. I got the highest
drop rate from this switch, so numbers of the order of 20% are really
strange.
Anyway, this is not important for the question of where to mirror from.
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