Packet Transmission between 2 points

Unanswered Question
Sep 10th, 2007
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I have a general question.

Is there a MAX time a packet will live on a wire between 2 points?

(2 sec max?)

I tried to find some documentation on this but can't. TTL doesn't fully explain what I'm looking for. Seems TTL is variable. I was wondering if there is a max time..


Any help would be greatly appreciated.


thank you

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rais Mon, 09/10/2007 - 08:40
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TTL is the mechanism to control the life of a packet on net.


TTL expresses life as number of hops. For IP it's max 255. Each router decrements the TTL as it receives the packet. Once TTL decrements to zero, the packet is discarded.


Thanks.

jemorton Mon, 09/10/2007 - 08:48
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Thanks for the reply. But my questions is really (in seconds) what is the max time a packet can live before being discarded?


thank you!

avmabe Mon, 09/10/2007 - 08:51
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There is not an answer for your question. That is not something defined by any RFC.

Joseph W. Doherty Mon, 09/10/2007 - 08:57
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Actual time depends on how long it takes for the TTL to reach zero. Depends on initial TTL setting and time for packet to transit each hop.

Joseph W. Doherty Mon, 09/10/2007 - 08:54
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For IP


What might be causing confusion is TTL, time-to-live, doesn't normally run against any real-time clock, it's usually just a limit on the number of "hops" a packet can make. Normally routers decrement the value by 1. When it reaches zero, the packet is no longer forwarded.


If there's a routing loop, this will eventually destroy the packet. It could happen very quickly on a LAN or take much, much longer on a low bandwidth but high latency WAN links.


Richard Burts Mon, 09/10/2007 - 09:25
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Jesse


As several people have pointed out there is not any limit on actual time that an IP packet can exist (there is no discard based on expiration of some timer). There are several reasons why there is no such expiration of a packet. One of the reasons is that we do not have any mechanism to accurately know when the packet was generated, so we can never know accurately how long the packet has existed, and therefore can never know precisely when the packet should expire.


TTL is as close as there is to what you are looking for.


HTH


Rick

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