3 ms·
I'll add an extra bonus: every now and then, an endpoint could append one extra bonus byte to a transmitted packet. That would probe for a potential increase i
by amluto 3y ago
I'll add an extra bonus: every now and then, an endpoint could append one extra bonus byte to a transmitted packet. That would probe for a potential increase in PMTU at very little cost.
- zamadatix 3y agoYeah, maybe a "contains MTU dummy data" bit at the start of the header which lets the receiving client know that this packet 1) May contain additional data after the real payload 2) If it does, send back an updated max packet size based on the amount that made it through. IETF folks wouldn't like that much state in the IP protocol and it doesn't solve intermediate L2 loss (the real reason you have IP MTU differences) when switches are involved in the path though. That said, might make in interesting ICMP probing method.
- toast0 3y agoIn TCP, for packets without the urgent bit set, you could include the real size of the data in the urgent pointer field. The sender could occasionally send a local max MTU packet with at most the detected path mtu of data. The receiver could send a return indicator to confirm the received length if the urgent pointer field was set.