I tested it on Windows 7 and Ubuntu 11.10 with MTU size 1500B.
- IP packet - 20B
- ICMP packet - 8B
1500 - 28 = 1472
So maximum packet that I could ping without fragmentation is 1472B, and this is correct, because when I try set higher value, it shows that fragmentation is needed. But maximum value when ping is successful, is 1448 on both systems. When I try values between 1449 - 1472 bytes I get time out. Why is that?