Unanswered Question
Feb 26th, 2008

Hi all, is fragmentation a packet smaller than 64bytes, do switches pass this traffic or drop them, as ive read its classed at a corrupted packet ?

I have this problem too.
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Hi Carl

It is my understanding that fragmentation happens when a packets larger then 1518 bytes (or 1522 bytes according to IEEE 802.3ac)is received by the switch.

A frame smaller than 64 bytes would I believe be considered a mal formed packet and is known as a runt. I belive that if a frame was received which was only 64 bytes in size it would be dropped as it is my understanding that even if there were only 64 bytes of data to be transmitted, a normal frame would be "padded" to make it up to 1518/1522 bytes.

The Fragment free method of switching that your learn about in your CCNA studies checks the first 64 bytes of a frame for corruption and if none is found the frame will be forwarded. If corruption is found then the packet will be dropped.

Best Regards,


Joseph W. Doherty Tue, 02/26/2008 - 05:09

Possibly a bit of confusion here. The 64 byte minimum your reference is likely the minimum frame size for Ethernet. Switches should not forward such "runts".

Fragmentation of packets is when the original packet is larger then an intermediade physical link can transmit. Unless you set the IP flag not to fragment, the original packet will be divided into as many maximum size packets as necessary to forward.


Between this question and your other about half duplex, you might want to read:


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