[Click] Inflated packets

[kevin_mitchell at agilent.com]

I have a user-level click script running on machine A that sends a packet 50 bytes long to machine B.  Inserting a Print element immediately prior to sending the packet confirms it has this length.  On machine B I'm running a kernel-level click script.  If I insert a Print element immediately after receiving the packet, using FromDevice, it says the packet is now 60 bytes long.  If I know the payload contains an IP packet then I can insert a CheckIPHeader element, and this, as a side-effect, truncates the packet back down to the expected 50 bytes, by using the IP length in the header.  But I might not always have an IP header in the payload, so this won't always work.  Is this difference between the expected packet length, and the reported length, to be expected?
 
Kevin