Large RTT or Why doesn't my ping traffic get discarded?

Wed Dec 21 21:19:54 UTC 2022

There's this thing called bufferbloat...

On Wed, Dec 21, 2022 at 11:58 AM William Herrin <bill at herrin.us> wrote:
>
> On Wed, Dec 21, 2022 at 9:10 AM Jason Iannone <jason.iannone at gmail.com> wrote:
> > Here's a question I haven't bothered to ask until now. Can someone please help me understand why I receive a ping reply after almost 5 seconds?
> >
> > 64 bytes from 4.2.2.2: icmp_seq=398 ttl=54 time=4915.096 ms
> > 64 bytes from 4.2.2.2: icmp_seq=399 ttl=54 time=4310.575 ms
> > 64 bytes from 4.2.2.2: icmp_seq=400 ttl=54 time=4196.075 ms
> > 64 bytes from 4.2.2.2: icmp_seq=401 ttl=54 time=4287.048 ms
> > 64 bytes from 4.2.2.2: icmp_seq=403 ttl=54 time=2280.466 ms
> > 64 bytes from 4.2.2.2: icmp_seq=404 ttl=54 time=1279.348 ms
> > 64 bytes from 4.2.2.2: icmp_seq=405 ttl=54 time=276.669 ms
>
> Hi Jason,
>
> This usually means a problem on the Linux machine originating the
> packet. It has lost the ARP for the next hop or something similar so
> the outbound ICMP packet is queued. The glitch repairs itself,
> briefly, releasing the queued packets. Then it comes right back.
>
> Regards,
> Bill Herrin
>
>
> --
> For hire. https://bill.herrin.us/resume/

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