CN : Fregmentation

Question

In Ipv4 reassembly of the fragments is done at the only destination or at intermediate routers also?

Answer 1

From RFC 

The basic internet service is datagram oriented and provides for the
  fragmentation of datagrams at gateways, with reassembly taking place
  at the destination internet protocol module in the destination host

Fragmentation is done at intermediate routers(if any) and reassembly only at destination host.

check page 23 here https://www.ietf.org/rfc/rfc791.txt

Comments

@Saxena0612

In ipv6 although we dont have any fragmentation option in header of ipv6 but both end systems can fragment according to MTU.

IPv6 has fragmentation extension header. I did't get your statement

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Yes! check IPV6 and IPV4 headers , In ipv6 header the separate fragmentation part in header is removed but there is something known as external header which support all other information including fragmentation.

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But some firewall do reassembly so we can not sure reassembly at router  may be done or not