Joe Touch wrote: >> 9. ICMP >> >> ICMP does not carry any port information and is consequently >> problematic for address sharing mechanisms. > > ICMP messages are specifically intended to include enough of the > transport header to enable port demuxing at the end receiver. I think it says ICMP information messages such as echo request do not have port numbers. However, ID and sequence number field of echo request can be used (overridden) as source and destination port numbers, respectively. As the fields are copied as is from echo request to echo reply, ID and sequence number field of echo request must be used as destination and source (reversed) port numbers, respectively. It's implemented for end to end NAT and is working with "ping" and "traceroute". >> 11. Fragmentation >> >> When a packet is fragmented, transport-layer port information (either >> UDP or TCP) is only present in the first fragment. Subsequent >> fragments will not carry the port information and so will require >> special handling. > > ?INT? The ID will be incorrect too; it may not be unique as required > when viewed from the outside. Port based redirection MUST be done after fragmentation reassembly. That's all and is no special. Masataka Ohta _______________________________________________ Ietf mailing list Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf