Packet

Unanswered Question
Aug 3rd, 2010
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Dear all


I don't think,there is  a fix TTL value in every packet, i want to know, how ttl is managed in internet connection, where

the packet has to traverse across thousands of hops, please can u help me to avoid this confusion?


and what are the factors, that effects to assign the initial TTL value in a packet.


Thanks for a kind  response

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Nagaraja Thanthry Tue, 08/03/2010 - 11:06
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Hello,


Typically, the TTL value is set as per RFCs (1700 for example) which specify a value of 64 for IP packets. But different OS manufacturers use different values (between 1 to 255). Windows sets it at 128 (it can be changed through modifying registry values).


http://support.microsoft.com/kb/314053


Similarly, when you are doing traceroute, the TTL value will be started at 1 and for every hop, it will be incremented.


Hope this answers your questions.


Regards,


NT

Tharak Abraham Tue, 08/03/2010 - 22:44
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Hari,


TTL eventhough is time to live is decremented on everyhops (earlier RFC recommended a 1 sec decrement per hop)


Its a misconception that the packet has to travel through 1000 hops across the internet.

For eg: ive personally checked that it takes less than 20-25 hops between two nodes seperated by 5000 miles


You may check with a trace to google.com and confirm..-:)


The packets are decremented everyhop, starting from the value implemented w.r.t to the IP stack for that OS till the value reaches 0 and then would die.

The max value being 255 since TTL has 8 bits in the IP Packet header.


Hope to help,

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