Koliko ja znam to je max. za ADSL i ne može nikako da se poveća.
(TCP, IP, MTU and MSS magic numbers)
1500 The biggest-sized IP packet that can normally traverse the Internet without
getting fragmented. Typical MTU for non-PPPoE, non-VPN connections.
1492 The maximum MTU recommended for Internet PPPoE implementations.
1472 The maximum ping data payload before fragmentation errors are received on
non-PPPoE, non-VPN connections.
1460 TCP Data size (MSS) when MTU is 1500 and not using PPPoE.
1464 The maximum ping data payload before fragmentation errors are received
when using a PPPoE-connected machine.
1452 TCP Data size (MSS) when MTU is 1492 and using PPPoE.
576 Typically recommended as the MTU for dial-up type applications, leaving 536
bytes of TCP data.
48 The sum of IP, TCP and PPPoE headers
40 The sum of IP and TCP headers.
28 The sum of IP and ICMP headers.