Re: [tsvwg] UDP-Options: UDP has two ”maximums”

Gorry Fairhurst <gorry@erg.abdn.ac.uk> Fri, 02 April 2021 11:30 UTC

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From: Gorry Fairhurst <gorry@erg.abdn.ac.uk>
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Date: Fri, 02 Apr 2021 12:29:55 +0100
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Subject: Re: [tsvwg] UDP-Options: UDP has two ”maximums”
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In the last IETF TSVWG meeting you asked for throughts about what MSS 
should mean?

I have now thought - the key unknown here is how large a datagram 
segment the remote receiver is willing to accept - i.e., what is the 
largest fragmented datagram I can send that would be reassembled. This 
might be any number, depending on the way in which the receiver is 
designed or configured. Whereas a sender could anticipate a common 
fragment size - e.g. 1200B, or use dplpmtud to discover this, there is 
no real way of determining the largest datagram that would be the option.

I think you suggested this as: Max reassembly size, a hard upper bound, 
similar to MSS_R.

Does this help?

Gorry