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

Joelle Maslak jmaslak at
Wed Dec 21 22:12:49 UTC 2022

You didn't tell us anything about your path or your endpoint, or if you see
this just with Lumen's DNS servers or with other devices.  So it is hard to
guess what is going on here.

That said, I know I've seen this kind of behavior both with buffer bloat on
consumer devices (particularly the uplink direction) and wifi networks
(which can have surprisingly deep buffers, with retransmissions occurring
at layer 1.5/2).  My guess is that there is a software routing/switching
device somewhere in the path (wifi AP, home router, Linux or BSD router,

On Wed, Dec 21, 2022 at 10:10 AM Jason Iannone <jason.iannone at>

> 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? As I
> understand it, buffers in SP gear are generally 100ms. According to my math
> this round trip should have been discarded around the 1 second mark, even
> in a long path. Maybe I should buy a lottery ticket. I don't get it. What
> is happening here?
> Jason
> 64 bytes from icmp_seq=392 ttl=54 time=4834.737 ms
> 64 bytes from icmp_seq=393 ttl=54 time=4301.243 ms
> 64 bytes from icmp_seq=394 ttl=54 time=3300.328 ms
> 64 bytes from icmp_seq=396 ttl=54 time=1289.723 ms
> Request timeout for icmp_seq 400
> Request timeout for icmp_seq 401
> 64 bytes from icmp_seq=398 ttl=54 time=4915.096 ms
> 64 bytes from icmp_seq=399 ttl=54 time=4310.575 ms
> 64 bytes from icmp_seq=400 ttl=54 time=4196.075 ms
> 64 bytes from icmp_seq=401 ttl=54 time=4287.048 ms
> 64 bytes from icmp_seq=403 ttl=54 time=2280.466 ms
> 64 bytes from icmp_seq=404 ttl=54 time=1279.348 ms
> 64 bytes from icmp_seq=405 ttl=54 time=276.669 ms

Ms. Joelle Maslak
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