Questions tagged [mtu]
"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.
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OpenVPN: Accessing devices without PMTUD via VPN: how to allow 1,500 byte packets to pass through unmodified?
I'm trying to see if I can access a particular type of switches over an OpenVPN connection. I have the following situation;
I can't access the management console of these type of switches, as they ...
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How to demo ICMP Type 3 Code 4, Fragmentation Needed and Don't Fragment was Set
I would like to demo a situation where the MTU traffic is higher than one accepted. So, source would receive the ICMP Type 3 Code 4 as reply.
I am trying with two Linux instances running on AWS. Both ...
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Issue with MTU 9000 Configuration: Jumbo Frames Not Working
Problem Description
I'm experiencing issues with configuring jumbo frames (MTU 9000) on my network. When I set all relevant interfaces to an MTU of 9000, connectivity fails for larger packet sizes. ...
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New network not using updated TLS and failing to connect to certain websites
I have 2 networks that are configured just about identically. The both have the same Router - Mikrotik RB2011UiAS-RM, with a direct fiber link to the ISP. I am using the same ISP for both networks. ...
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Ping with jumbo frames fail but returns default ping fail message
I need to set up a local connection between my Windows 11 PC and an external device (IP 10.0.0.10), with jumbo frames enabled (MTU 9000). The end goal on my PC is to connect to the remote device from ...
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MTU resetting back to 1500 after `netplan apply`
I'm trying to change the MTU of the eth0 interface on my machine running Ubuntu 18.04 (Nvidia Jetson Xavier NX). Running sudo netplan apply successfully sets the mtu for eth0 to 1280.
Unfortunately, ...
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What's magical about MTU and packet drops?
With default MTU as shown below:
hosta$ ifconfig eth0 | grep mtu
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
I can ping from a different server using a 1500 payload
hostb$ ping -...
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strongSwan VPN tunnel (IKEv2) established but traffic times out
I have a VPN server that tunnels traffic to a PostgreSQL database server which is otherwise unreachable from the internet. The VPN is only reachable by IPv4.
Problem
All clients can establish a VPN ...
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which Wireguard MTU is chosen when each side has a different MTU value?
tl;dr given a Wireguard client and server with different MTU values, which value is used?
Given a Wireguard "client" with configuration file
[Interface]
MTU = 1440
...
and a Wireguard "...
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OpenConnect force clients to use special cipher
I use ocserv on Centos as Openconnect VPN and I use config file for setting up the server
I need to force clients to use special cipher like AES-256-GCM
because it seems that VPN blocks on some 4G net ...
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Jumbo MTU and switches
I have a network with several file servers, workstations and application servers. For simplicity we can consider it all attached to a single switch, say Dell 4032F with maximum Jumbo MTU size of 9216. ...
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"very high" (probably?) MTU being set automatically on wireguard interface
So, I have a VPS running on Amazon Lightsail and I installed wireguard on it; I setup an interface this way:
[Interface]
Address = 10.255.128.1/24
MTU = 1420
SaveConfig = true
PostUp = iptables -A ...
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forwarded TCP traffic is refragmented on Linux despite the "Don't fragment" flag
We have 2 VPN servers at the same hoster. The servers are virtual and they have different Linux distros. The VPN clients establish https connections to the same Amazon EC2 server. The TCP packets from ...
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PMTUD/ICMP black hole problems across a VXLAN tunnel
I'm running a Proxmox PVE host and am trying to use VXLAN to connect the machines running on it to various networks in our Lab. However, I'm running into weird MTU-related problems that I don't ...
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Increasing MTU size
Why would increasing the VLAN MTU size cause things to break?
We have a customer who wants 2000 byte packets for some reason, so I increased all the physical links to 9216, which didn't cause any ...
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