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

Jason Iannone jason.iannone at
Thu Dec 22 12:35:43 UTC 2022

Thanks for engaging with this. I was intentionally brief in my explanation.
I have observed this behavior in congested networks for years and ignored
it as an obvious symptom of the congestion. What has always piqued my
curiosity though is just how long a ping can last.

In my case yesterday, I was at the airport at peak holiday travel and free
wifi usage time. I expect a bad experience. I don't expect a ping to return
5 seconds after originating it. I just imagine the network straining and
groaning to get my ping back to me. It's okay, man. Let it go.

On Thu, Dec 22, 2022 at 5:22 AM Masataka Ohta <
mohta at> wrote:

> Jerry Cloe wrote:
> > Because there is no standard for discarding "old" traffic, only
> > discard is for packets that hop too many times. There is, however, a
> > standard for decrementing TTL by 1 if a packet sits on a device for
> > more than 1000ms, and of course we all know what happens when TTL
>  > hits zero. Based on that, your packet could have floated around for
>  > another 53 seconds.
> Totally wrong as the standard says TTL MUST be decremented at least
> by one on every hop and TTL MAY NOT be decremented further as is
> specified by the standard of IPv4 router requirements (rfc1812):
>     When a router forwards a packet, it MUST reduce the TTL by at least
>     one.  If it holds a packet for more than one second, it MAY decrement
>     the TTL by one for each second.
> As for IPv6,
>     Unlike IPv4, IPv6 nodes are not required to enforce maximum packet
>     lifetime.  That is the reason the IPv4 "Time to Live" field was
>     renamed "Hop Limit" in IPv6.  In practice, very few, if any, IPv4
>     implementations conform to the requirement that they limit packet
>     lifetime, so this is not a change in practice.
>                                                 Masataka Ohta
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