[freenet-dev] Path MTU discovery

[toad]

Does anyone have any concrete ideas on how to do PMTU in Freenet?

So far, these seem to be the options:

- Fixed maximum packet size, at the moment this is 1400-28 (28 being
  UDP headers).
- The above, but can be overridden by nodes who know their local MTU;
  the overridden maximum sizes would be exchanged on connection setup.
- PMTU discovery using native code.
- PMTU discovery based on packet loss statistics. We would record the
  sizes of packets recently successfully sent and lost, and try to
  identify a threshold below which packet loss is significantly lower.
  Not sure if this is feasible in the general case.

In any case the next step is the new congestion control code, which
should make packet loss due to oversize packets being sent less of a
catastrophe. The above are on the assumption that we have congestion
control.
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