under sized frame

Feb 02, 2007 2 Replies
K

Hi,



I have a doubt on the under sized frame. The standard says that the minimum frame size is 64 bytes. What will happen if we send a frame of size less than 64 to a device?



Lets take an example of ARP Request. I add a ARP packet inside a frame and make the frame size less than 64 bytes without any padding length=(ARP Packet size + Ethernet Header and Trailer) and send it to a device.



I have few questions based on the above scenario:


  1. Will the packet be ignored?
  2. Will we get a ARP reply for that packet?
  3. Will it get counted as under sized frame?

Any answers would be of great help.



Thanks in advance.



Regards, Sriram k



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D

According to the standard, it has to be dropped by the receiver. If you have a managed switch, you will see it as "undersize" in RMON statistics.

A frame less than 64 bytes in Length is not an Ethernet Frame. The standard requires padding up to the minimum frame length, should header and payload underrun the minimal frame length.

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M

Bonjour Denis and Ksriram,

You can send undersized frames when the Ethernet MAC layer is transmitted over an other server layer than PHY.

For example, Ethernet MAC over RFC 2684: with PID = 7 the equipments at both ends can agree that there is no padding added.

Best regards, Michelot

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