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Fragmentation is done by Network layer or Transport Layer ?

asked in Computer Networks by Active (2.4k points) 3 21 42 | 386 views

3 Answers

+1 vote
fragmentation is done by network layer  and  generally  by  a router

 and it is required because if there is network where MTU is less than  paket size

then  there fragmentation is required.

 

fragmentation is nothing but  dividing paket into fragments so new pakets could could fit into a frame

whose MTU is less than original packet

 

it  is never done  on  source computer,  it  is  always  done by routers  and  it  is done  at layer 3  -- network layer

 

on   tranport  layer (source computer )  segmentation is done  such that it  gets  easily fit into  FRAME of data link layer

so to avoid fragmentation on this DLL(dat link layer).
answered by Junior (753 points) 2 9
0 votes

fragmentation is done by network layer as per according to size of MTU(MAXIMUM transfer unit).

answered by Veteran (21.4k points) 30 102 201

But in Frouzan its written "Source usually dont fragment IP packet. The transport layer instead segment the data into a size that can be accomodated by IP and the link layer in use"

yea true source dont do fragmentation...it is done by the routers...source only do segmentation according to the MTU of the DLL at the transport layer....when u segment the data packet at TL and send it to router...router will do fragmentation based on the MTU of other network(using offset,MF,total length and header length)....so in short
SOURCE WILL DO SEGMENTATION AT TRANSPORT LAYER

ROUTERS WILL DO FRAGMENTATION AT NETWORK LAYER

DESTINATION WILL DO REASSEMBLY OF FRAGMENTS
Yes true, but still there is a chance where source will do fragmentation when DF flag is set to 1. Upon receiving the ICMP packet from router, it will fragment the datagram at source and resend the datagram as per the MTU received.
0 votes
fragmentation is done at network layer
answered by (121 points) 2


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