Peterson Davie 3.38c

Question

Suppose an $IP$ packet is fragmented into $10$ fragments, each with a $1$% (independent) probability of loss. To a reasonable approximation, this means there is a $10$% chance of losing the whole packet due to loss of a fragment. What is the probability of net loss of the whole packet if the packet is transmitted twice,

(c) Explain how use of the Ident field might be applicable here.

Answer 1

c)An implementation might (though generally most do not) use the same value for Ident when a packet had to be retransmitted. .

Answer 2

No we cannot use same ID FIELD of FRAGMENTED PACKETS again for two valid reasons

1) ID FIELDS are generated by a counter so its having a lifetime(for eg:120ms) might change next time of retransmission.

2)retransmission can also be done from another place which is different from the previous place of transmission.

ID FIELD always maintain its UNIQUENESS all the time.