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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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Under FreeBSD, can a VLAN interface have a smaller MTU than the primary interface?

I have a system with two physical interfaces, combined into a LACP aggregation group. That LACP channel has two VLANs, one untagged (the "native vlan") and one using VLAN tagging. This gives us: lagg0:…
larsks
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What should be the MTU Size for Windows Servers on the same Network

I have two windows servers on the same network, communicating to each other. What would be the best way to come up with the MTU setting?
win08r2newbie
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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. My first network has been up and running with no…
fatdollar
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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 WSL2, which currently works but has the same MTU…
C. Crt
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Unable to receive TCP packets larger than VPC MTU on Google Compute Engines (Redis Client)

This seems to be network issues between Redis cluster (Deployed on our site's on-prem worker node) and Redis client (On GCP VM that is connected to our site via Cloud VPN). Specifically, the issue is related to the unresponsiveness of the Redis…
Sung-IL
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How is the correct MTU used for connections through an IGW on EC2

If you bring up a couple of default image VMs in the default VPC in EC2, they will generally have their interface MTU set to 9001. If you sent TCP traffic between those two instances using their private IP addresses, it is easy to verify that full…
BeeOnRope
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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, within a minute, my SSH connection is dropped. I…
Ben Butterworth
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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 connection. Some clients can't connect to the…
ffrosch
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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 by a strange firewall and I need to bypass that…
Farhad Sakhaei
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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. I would appreciate your help with some questions…
Dima
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Cannot transfer data from one specific system (MTU issue?)

Summary The default MTU value prevents data transfer for one system. Reducing it manually enables the data transfer once more, but this manual adjustment is unnecessary on an adjacent system. Background I have a Backups Server. I have two Raspberry…
roaima
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How to change cisco 3750 specific port MTU to 9000?

How to change cisco 3750 specific port MTU to 9000? I do not want to set it as a system global command for all ports.
hamid
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Why does setting MTU 1452 solve Internet problems and how to fix root cause?

In our church we get Internet uplink from a friendly neighbor’s WiFi. At first everything seemed (at least) fine but since some weeks general “Internet stability problems” increased and since approx. 2 weeks my Raspberry Pi on site couldn’t…
Daniel Böhmer
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I can not decrease MTU on my nic

I'm trying to decrease the MTU value on my machine but I receive this response: [root@apache1bpreprod acn]# ifconfig eth0 mtu 1350 SIOCSIFMTU: Invalid argument Why? i expect problems to increase not to decrease. Can you help me? Thanks a lot
Peppe Del Prete
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VMWare - Jumbo Frames over iSCSI to a NAS4Free array

I am having problems getting Jumbo Frames working over my iSCSI connection. Here is what I try. 4 1GbE connections on 4 different subnets on my NAS4Free array for iSCSI, MTU set at 9000 2 redunant switches with the MTU set at their maximum 12288(or…
Litzner
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