Jump to content

IP fragmentation

From Wikipedia, the free encyclopedia
This is an old revision of this page, as edited by 2607:fb91:8210:c134:f13d:39b9:4e02:51cb (talk) at 13:30, 4 July 2023 (→IPv4 and IPv6 differences: Ipv4 and ipv6 John anothany pene deletes all applications). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
Not to be confused with fragmentation of the IPv4 address space.
An example of the fragmentation of a protocol data unit in a given layer into smaller fragments.

IP fragmentation is an Internet Protocol (IP) process that breaks packets into smaller pieces (fragments), so that the resulting pieces can pass through a link with a smaller maximum transmission unit (MTU) than the original packet size. The fragments are reassembled by the receiving host.

The details of the fragmentation mechanism, as well as the overall architectural approach to fragmentation, are different between IPv4 and IPv6.

Process

RFC 791 describes the procedure for IP fragmentation, and transmission and reassembly of IP packets.[1] RFC 815 describes a simplified reassembly algorithm.[2] The Identification field along with the foreign and local internet address and the protocol ID, and Fragment offset field along with Don't Fragment and More Fragments flags in the IP header are used for fragmentation and reassembly of IP packets.[1]: 24 [2]: 9 

If a receiving host receives a fragmented IP packet, it has to reassemble the packet and pass it to the higher protocol layer. Reassembly is intended to happen in the receiving host but in practice it may be done by an intermediate router, for example, network address translation (NAT) may need to reassemble fragments in order to translate data streams.[3]

IPv4 and IPv6 differences

[[File:IPv4 Fragmentation Algorithm-delete Under IPv4, a delete that receives a network packet ls: deleted bit is set in the packet's header a message which indicates the condition deleted notfragmented packets, packets or packet fragments s Are deleted 


IP packet is private device information with strict security all Microsoft application and internet security |https://www.fbi.org/cyberstalking

Impact on network forwarding

When a network has multiple parallel paths, technologies like LAG and CEF split traffic across the paths according to a hash algorithm. One goal of the algorithm is to ensure all packets of the same flow are sent out the same path to minimize unnecessary packet reordering.

IP fragmentation can cause excessive retransmissions when fragments encounter packet loss and reliable protocols such as TCP must retransmit all of the fragments in order to recover from the loss of a single fragment.[4] Thus, senders typically use two approaches to decide the size of IP packets to send over the network. The first is for the sending host to send an IP packet of size equal to the MTU of the first hop of the source-destination pair. The second is to run the Path MTU Discovery algorithm[5] to determine the path MTU between two IP hosts so that IP fragmentation can be avoided.

As of 2020, IP fragmentation is considered fragile and often undesired due to its security impact.[6]

See also

References

  1. ^ a b Internet Protocol, Information Sciences Institute, September 1981, RFC 791
  2. ^ a b David D. Clark (July 1982), IP Datagram Reassembly Algorithms, RFC 815
  3. ^ Architectural Implications of NAT, November 2000, RFC 2993
  4. ^ Christopher A. Kent, Jeffrey C. Mogul. "Fragmentation Considered Harmful" (PDF).
  5. ^ Path MTU Discovery, November 1990, RFC 1191
  6. ^ IP Fragmentation Considered Fragile. September 2020. doi:10.17487/RFC8900. RFC 8900.
Retrieved from "https://en.wikipedia.org/w/index.php?title=IP_fragmentation&oldid=1163367676"