[e2e] purpose of pseudo header in TCP checksum

Wesley Eddy weddy at grc.nasa.gov
Tue Feb 15 10:19:44 PST 2005

On Tue, Feb 15, 2005 at 06:46:20PM +0100, Michael Welzl wrote:
> So we need to specify that link layers DO check the headers
> and just do NOT check the payload if it's a UDP Lite packet.
> This is the part that I consider inevitable (given the
> current situation) but ugly.

Actually, with UDP-Lite, you'd be asking the link layers to parse up
through the transport layer and check as much of the data as the
UDP-Lite header designates as sensitive.  That's slightly more complex
than just checking the protocol field in IP header, which already
assumes that the link device can parse IP, can see through whatever
levels of tunnels are present, etc.  The reasonableness of the
architecture that UDP-Lite would like to operate in seems rather
questionable to me.


Wesley M. Eddy
NASA GRC / Verizon FNS

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