Is message segmentation and switching the same thing?

Segmentation is when the max transmission unit is smaller than the size of the data packet, so we have to break it up into multiple packets.

Switching is just breaking up the packet to get to a destination, for some reason?

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    – Ron Maupin
    Dec 21, 2020 at 18:10

2 Answers 2


Segmentation (or rather fragmentation)

Although in some literature you may find the term segmentation to refer to the process of dividing an IP packet that is bigger than the Maximum Transfer Unit (MTU) of the link, the correct term is fragmentation.

See @adam86 answer for what segmentation refers to.

Switching is totally different, it refers to the process, performed by devices commonly known as switch, although the official term is mac bridge, which transfer (unchanged), an Ethernet frame from a LAN to another LAN.
Mac bridges are defined by the IEEE standard 802.1D

In modern Ethernet networking, switching is performed when a switch receives an Ethernet frame on one of its ports and transfers it to another port on which the receiver is attached.

The switch use the destination MAC address present in the Ethernet frame to select the port to send the frame to.

The term "switching" come from the fact the frame is recopied from one port to another one, by opposition with older hubs which send the frame to all ports (except the one on which the frame was received).


TCP breaks up a message into small pieces known as segments. This process is called segmentation. Keep in mind that TCP is a byte stream protocol. It's up to Layer 4 to create chunks not bigger than the Maximum Segment Size which is the largest segment (piece of data) that can be transferred in an IP packet which in turn is limited by MTU that is the maximum size of a packet that can traverse a given physical link.

@JFK The term segmentation is sometime used to refer to the process of dividing an ethernet frame that is bigger than the Maximum Transfer Unit (MTU) of the link

isn't this called fragmentation?

HTH Adam

  • did you read the end of my sentence? "but this is more generally referred as fragmentation."
    – JFL
    Apr 20, 2016 at 7:08
  • I didn't want to offend you by any means. Yes I did. But calling it segmentation is not the right term. It's fragmentation. :-) to the best of my knowledge.
    – cyzczy
    Apr 20, 2016 at 7:09
  • no offense taken, I agree with you, this is the op that used the term. I'll edit my answer to better reflect that this usage is not quite correct.
    – JFL
    Apr 20, 2016 at 7:12
  • @JFL, actually, fragmentation is part of the IP (layer-3) protocol, not layer-2. Fragmentation happens at layer-3, but layer-2, like ethernet, will just discard oversize frames, not fragment them.
    – Ron Maupin
    Apr 20, 2016 at 14:29
  • @RonMaupin, yes you're right of course. Thanks.
    – JFL
    Apr 20, 2016 at 15:02

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