I'm running Ubuntu Server 12.04 LTS, and I want to override the MTU my cable company provides via DHCP. They provide an MTU of 576 and I want to use 1492. I can change it with ifconfig, but it won't persist across reboots.
576 bytes is the minimum size of IPv4 datagram every device has to be able to receive (it can be whole or fragmented). Browse other questions tagged tcp ip mtu Meeting #576 of the University Senate of Michigan Technological University will convene at 5:30 p.m. on Wednesday March 23, 2016 in Room 642 in the DOW Building. Senators are responsible for making their constituents aware of the agenda for this meeting. I believe the MTU of 576 was an expectation (standard) that any IP media would at least support that. So, IP, if it doesn't know otherwise, it assumes a MTU of 576. As for MSS being 536, that's assuming that the MTU is 576 and also assuming the IP and TCP headers are their minimal sizes of 20 bytes each this allow a TCP MSS of 536 (576 - 40). You probably have an MTU/fragmentation problem. For each network interface on both client and server set the MTU to 576, eg ifconfig eth0 mtu 576. If the problem goes away, read on. Long Answer Long answer: At each routing hop, IP packets bigger than the outgoing interface's Maximum Transmission Unit (MTU) get fragmented.
The db variable tm.minipfragsize is set to 576 by default on the image 11.5.1-hf6. What this means is that BIG-IP system does not process packets with a payload length of less than 576 bytes. When MTU is set to 576, the payload length is 576. Because IP header length is 20 bytes typically, the BIG-IP system drops the 576 byte-fragmented packets.
Meeting #576 of the University Senate of Michigan Technological University will convene at 5:30 p.m. on Wednesday March 23, 2016 in Room 642 in the DOW Building. Senators are responsible for making their constituents aware of the agenda for this meeting. I believe the MTU of 576 was an expectation (standard) that any IP media would at least support that. So, IP, if it doesn't know otherwise, it assumes a MTU of 576. As for MSS being 536, that's assuming that the MTU is 576 and also assuming the IP and TCP headers are their minimal sizes of 20 bytes each this allow a TCP MSS of 536 (576 - 40). You probably have an MTU/fragmentation problem. For each network interface on both client and server set the MTU to 576, eg ifconfig eth0 mtu 576. If the problem goes away, read on. Long Answer Long answer: At each routing hop, IP packets bigger than the outgoing interface's Maximum Transmission Unit (MTU) get fragmented. Ogata Yasuhiko @yogata. RFC1812にIPv4の最小MTUが576と書いているって見たんだけれど、そうじゃないような。MTUを576にしてパケットフラグメントを防ぐテクニックがあるよ、とは書いているけれど、最小MTUサイズは576バイトと明示してはいないなぁ。
Specifically, the size of the header to subtract from the MTU (whether it is the MTU of the outgoing interface or IP's minimal MTU of 576 bytes) is now at least 18 bytes larger. This is incorrect. The value for the MSS option is only adjusted by the fixed IP and TCP headers.
For example, the MTU of many PPP connections is 576, so if you connect to the Internet via PPP, you might want to set your machine's MTU to 576 too. Most Ethernetnetworks, on the other hand, have an MTU of 1500, which is the default MTU setting for Windows 95. ifconfig # only change is the 1500 mtu netstat -4rnW Routing tables Internet: Destination Gateway Flags Use Mtu Netif Expire default xxxxxxxx UGS 218 576 vtnet1 127.0.0.1 link#4 UH 45553 16384 lo0 xxxxxxxx link#2 U 1085 1500 vtnet1 xxxxxxxx link#2 UHS 1 16384 lo0 xxxxxxxx link#1 U 29546475 1500 vtnet0 xxxxxxxx link#1 UHS 0 16384 lo0 xxxxxxxx link#8 U 0 1500 vtnet0_vlan4 xxxxxxxx link#8 UHS 0 3. Our MTU size is 1500 which is the default MTU size on most systems. Change Windows MTU Size. 1. Open a Command Prompt CMD (Right Click CMD -> Run Ad Administrator) 2. Type the following commands in order. netsh interface ipv4. 3. Your command window will now be at the prompt to change MTU using the next command below. 4.