Ethereal-users: Re: [Ethereal-users] Packet Length calculation is odd ???

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From: David Moore <davem@xxxxxxxxx>
Date: Fri, 08 Jun 2001 17:07:22 -0400
Nevermind, I see it! The extra 14 bytes is the ethernet header above and beyond the IP.

David Moore wrote:
> 
> I don't understand the packet length calculation. In a series of telnet session captures, Ethereal
> indicates three back-to-back packets and their lengths as 1514, 1514, and 242.
> 
> The maximum ethernet packet including header is 1500 bytes. The difference between the packet
> "Sequence number" and "Next sequence number" is 1460. This plus a standard 40 byte header is a full
> 1500 byte ethernet frame. So where does the 1514 come from ? This is 54 bytes too high not including
> the header, or 14 bytes too high with the header.
> 
> Similarly the last packet indicates a length of 242 bytes. However, the sequence number difference
> correctly show 188 bytes. Again there is a 54/14 byte error (depending on whether it's intended to
> include the header).
> 
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