Server Fault Stack Exchange
Server Fault Stack Exchange

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.

155 questions
2
votes
1 answer

VMWare ESXi 4.1 VMXNET Ignoring MTU and Sending Jumbo Frames

On my CentOS 5.6 ESXi 4.1 VMs using VMXNET, it looks like they are attempting to send jumbo frames: However, all the interfaces are set to MTU 1500. What is causing this behavior? Update: I would think that regardless of the switch, wouldn't…
Kyle Brandt
  • 83,619
  • 74
  • 305
  • 448
2
votes
2 answers

Why do I see an IP packet with size 2960, way above the MTU setting of 1500 on the interface and it gets through?

I am analyzing traffic between a client and a Linux webserver running on a HP blade server, the client sometimes gets stuck waiting for more data when the webserver has closed the connection. The webserver runs apache2 that for some reason choses to…
ernelli
  • 307
  • 1
  • 5
  • 15
2
votes
1 answer

Optimal MTU settings ADSL for PPPoE over ATM/LLC

Is 1446 optimal for PPPoE over ATM/LLC as this forum post describes?
robel
  • 21
  • 3
2
votes
1 answer

Telecom provider not supporting MTU higher than 1515 for leased line

We have ordered a 100 Mbps leased line and did not specify our requirement to have a minimum of 1530 MTU supported. The telco now sent us a feedback that they do not support 1530, but only 1515. Did anyone experience something similar? And what can…
Paul Moe
2
votes
1 answer

Can't reach server probably caused by openvpn mtu

What I try to achieve: Reach the server on LAN via OpenVPN Symptoms: SSH connection hangs on SSH2_MSG_KEXINIT ssh -vvv emmy@10.0.0.101 OpenSSH_8.2p1 Ubuntu-4ubuntu0.2, OpenSSL 1.1.1f 31 Mar 2020 debug1: Reading configuration data…
Benedikt Lang
  • 21
  • 2
1
vote
0 answers

MTU 9000 and 1500 when machines with MTU 1500 send data to machines with MTU 9000

we have some machines in the cluster linux machines as Linux_a , linux_b are configured with MTU 1500 while linux machines - linux_1 and linux_2 are configured with MTU 9000 so linux machines - linux_a and linux_b send heavy data to linux_1 and…
shalom
  • 461
  • 13
  • 29
1
vote
2 answers

can we mix MTU values in cluster

we have hadoop cluster ( all machines are linux redhat machines version 7.x ) on the VM machines we set MTU=8900 and all other machines we set MTU=9000 we set on VM MTU=8900 because we saw some network problems with MTU=9000 My question: dose mix…
shalom
  • 461
  • 13
  • 29
1
vote
1 answer

Problems with TCP retransmission, duplicates etc. on CentOS Linux

I'm running Vyattagateway with a CentOS Linux behind, and IPSec tunnel in front. Trying to display my setup: PARTNER-NETWORK <--- IPSec (GRE, MTU 1420) ---> VYATTA (TUNNEL, MTU 1420 <> eth0, MTU 1500) <---> CentOS (eth0, MTU 1500) <---> internet…
Alfred Balle
  • 409
  • 3
  • 9
  • 22
1
vote
2 answers

how to know if my servers should use huge pages ( memory page size )

we have several servers in cluster , and we want to know what in general in which cases we need to configure huge pages ? I have also few quastions dose "memory page size" is equal to Huge pages ? in my linux server I entered the following command…
shalom
  • 461
  • 13
  • 29
1
vote
1 answer

Random connection resets between browser and Linux server - MTU wrong or ICMP not getting through?

I've been seeing random ERR_CONNECTION_RESET errors in my browser (Chrome, Firefox or Edge running on different machines, Windows 10 1709) when I try to edit web pages on a remote Linux server running Ubuntu 16.04 LAMP. It's very hard to pinpoint…
Phil McKerracher
  • 346
  • 1
  • 6
1
vote
1 answer

VLAN MTU on Linux with Intel Pro/1000 PT Server Adapter

For some reason MTU still seem to be an occasional issue with trunked connections. In this case I have a trunk connected to an Enterprise Linux 5 server. I use standard vlan seperation in Linux, and have the vlan interface bridged with virtual…
Roy
  • 4,376
  • 4
  • 36
  • 53
1
vote
3 answers

ping fails with MTU >= 298

For context, my original problem is that my ssh connection to my servers hangs at expecting SSH2_MSG_KEX_ECDH_REPLY when i connect to them via VPN (in this case, an OpenVPN running in pfsense). The Internet indicates that may be linked to MTU…
iCart
  • 113
  • 3
1
vote
0 answers

VirtualBox adapter MTU settings over 1500

I create an adapter for Oracle VirtualBox (as a host-only). It runs perfectly; but I need to change MTU size to 1600. When I come back to host-PC and I opened terminal. Then I got these results. ifconfig : ..... vboxnet0 Link encap:Ethernet HWaddr…
user428688
  • 11
  • 2
1
vote
2 answers

Is there a utility or way to get the PMTU/MTU of a remote system quickly?

Is there a utility or linux built in to get the PMTU/MTU of a remote system quickly (sub 1 second preferably)? If so what is it and what syntax does it require? Google searches have not been my friend today and the only solution I've found is a full…
Bravo Delta
  • 140
  • 1
  • 9
1
vote
1 answer

Jumbo frames (mtu 9000) on Debian 7.10 servers with BCM57800 NIC (bnx2x)

I'm working on 2 servers under Debian 7.10 with Broadcom Corporation NetXtreme BCM57800 1/10 Gigabit ethernet. I have done the following for both servers: ethtool -g eth0 Ring parameters for eth0: Pre-set maximums: RX: 4078 RX Mini:…
Eliot B.
  • 13
  • 3
1 2 3
…
10 11