3 ms·
> ipv4 TTL is dejure seconds Huh. TIL. But how would a router know how long a packet took to traverse the hop? The packet doesn't have the information to figur
by deathanatos 3y ago
> ipv4 TTL is dejure seconds
Huh. TIL. But how would a router know how long a packet took to traverse the hop? The packet doesn't have the information to figure that out … were they expecting people to configure routers to know how far away the previous hop was?
Also >1 second is most of the way to moon. (Yes, yes, speed in a non-vacuum is blah blah and switches blah buffers blah…)
- js2 3y agoHere's what Jon Postel wrote in IEN 41[1] in June 1978: > The time to live is set by the sender to the maximum time the segment is allowed to be in the internetwork system. If the segment is in the internetwork system longer than that the segment should be destroyed. This field should be decreased at each point that the internet header [is] processed to reflect the time spent processing the segment. Even if no local information is available on the time actually spent, the field should be decremented. The time is measured in units of seconds (i.e. the value 1 means one second). Thus the maximum time to live is 255 seconds or 4.25 minutes. A router would have to track of when each packet enters and leaves and then round to the nearest number of seconds. [1]: https://www.rfc-editor.org/ien/ien41.pdf https://www.rfc-editor.org/ien/ien41.pdf