"Maximum Transmission Unit" (MTU) is the maximum number of bytes a frame or packet may have on a network (in several layers of the OSI model). Wrong MTU can lead to packet loss.
Questions tagged [mtu]
155 questions
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Reassembly fails at destination
Say I have Host1 & 2 connected to a router with different speeds.
Host1 <--100 Mbps--> Router <--10 Mbps--> Host2
Host1 sends 10MB of UDP data using nc command to Host2, but the Host2 fails in reassembling fragmented packets and sends…
Jeyaram
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HTTP webserver gateway timeout 504 only from one ISP
I have configured a nginx http webserver to serve a site on CentOS 6 Virtual machine. every things are works fine but when I connect to site from a special ISP, the site wait and after a while respond 504 Gateway timeout. This occurs only from this…
Ghasem Pahlavan
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How to setup linux to retransmit TCP packets by reducing the packet size like OS X
On OS X I noticed that for packets which are not ACKed, the system retransmits them with reduced packet size. This can be seen in the image below.
Is it possible to enable the same behavior in Linux systems too?
akshat
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Forcing IP fragmentation and reassembly for some traffic thru a VPN tunnel
Is there a way to force IP packet fragmentation before they go into tun0 and then force reassemble them on the other side of tun device?
I have some IPSec traffic that I can not control, and it wants 1500 MTU and just gets dropped at the tun…
grandrew
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Force Windows to send packets as soon as they arrive the nic
I have a network application running on Windows Server 2008 R2, that must send small packets in a very short time interval, each microsecond matters. My problem is that windows accumulates the packets and sends them in a big TCP packet, but I want…
Yekoor
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Server Not Working With Jumbo MTUs
I am a network engineer & my server guy doesn't appear to be able to get the jumbo MTU's to work on his NIC team. We are using LACP for two 10gig interfaces between the switch. I am 100% certain that the switch is configured for jumbo frames. And to…
john smith
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Change Xenserver 6.5 MTU
How do I go about change the MTU setting for my management interface in xenserver 6.5? Right now its set to the default 1500 but I want to increase it to 9000.
For my setup I have 2 nics on each host - 1 nic provides access to our data network and…
jrd1989
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Fragmented DNS Packet
The DNS response against my domain is 1228 bytes long and I need the packet to get fragmented in 3 packets. To achieve this I have set the MTU at name server (bind9 running on the machine) to be 500. TO verify that MTU is set to 500, I ping from the…
Salman Manzoor
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IPsec transport mode and MTU
[Similar to Right way to set the MTU of an IPsec Client (Linux/Racoon), but different in that there is no router on the responder side]
I have a setup where machines in a local network need to talk to a Linux server in a datacenter. The router for…
Simon Richter
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MTU between Juniper and Cisco, cause of packet loss?
This office has a network consisting of Cisco Catalyst and Juniper EX L3 switch. Cisco Router and Juniper L3 switch share a OSPF area in between them.
Hosts on Juniper side are running FTP servers and are keep running into packet loss that causes…
user192756
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Severe performance issues sharing openvpn client connection to LAN clients virtualbox
I am trying to set up an internal network in Virtualbox in order to share an openvpn client tunnel with multiple VMs acting as clients that should be completely isolated from everything except for the VPN tunnel interface, so as to prevent all…
fsonic
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Jumbo Frame configuration & VMware
I am hoping one of you can help clear up some of my confusion on this matter.
We have 2 new catalyst 3750 switches to support our VM hosts and SAN arrays. The SAN arrays utilize jumbo frames with an MTU of 9000.
In the switch config- we specified…
Mike P
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openvpn TCP/UDP slow SSH/SMB performance
I have question about strange behavior of my openVPN configuration on Debian lenny. I have 2 server configs (one proto tcp-server based and one proto udp based). ISP bandwidth is 7Mbit/7Mbit.
When I uses proto tcp-server my download server rate is…
Petr Latal
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Finding network type using MTU
For example MTU of Ethernet is 1500.
Now if the packets are fragmented, then observed MTU will be the MTU of the router (i.e. less than 1500).
Is there any method to find out the type of the client network reliably and accurately?
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Computer Networks bonus: find MTU less than 1500
This is a bonus question in my Networks class: I have to find a destination for which the path MTU < 1500 bytes.
For example using the command
traceroute -F www.uwaterloo.ca 1500 works, and traceroute -F www.uwaterloo.ca 1501 doesnt.
So I need to…
Stefan
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