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.

146 questions
4
votes
1 answer

Is there a way of setting an MTU lower for traffic destined to a specific IP address on Cisco ASA?

I have a number of VPN sites where the MTU is lower than standard (1500). I have had at least one site where fragmentation of packets has had an effect on the success of building an IPSEC tunnel. I am able to set the MTU on the equipment at the…
dunxd
  • 9,482
  • 21
  • 80
  • 117
4
votes
0 answers

Windows MTU can no longer be set higher than 1500 Bytes?

For some time we have been using jumbo frames on several computers without problems. But suddenly I am no longer able to increase the MTU on some computers to more than 1500 Bytes. netsh returns error for any MTU value higher than 1500: netsh…
Timmy Brolin
  • 91
  • 4
3
votes
3 answers

MTU problems? 'Request timed out'

I've been trying to figure out why some(very few) of the people who visit my site have random slowdowns and error pages('page cannot be loaded'). The random slowdowns and error pages never happen for me and most of the people who visit my site. The…
Echo says Reinstate Monica
  • 1,145
  • 3
  • 11
  • 16
3
votes
4 answers

How to set permanent mtu size for ppp0

Every time I connect to my VPN, I should run sudo ifconfig ppp0 mtu 1300 How could I make it permanent? I am using Ubuntu 14.04.
Mohse Taheri
  • 141
  • 1
  • 5
3
votes
1 answer

Full MTU not utilized with jumbo frames enabled

I've been testing to see if I can get any benefit from enabling jumbo frames. I've set up two identical Dell R210 servers with Xeon quad core E3122 CPUs, 8G of RAM and Broadcom NetXtreme II BCM5716 Gigabit Ethernet cards. I'm running Debian…
sevenr
  • 133
  • 1
  • 4
3
votes
2 answers

SFTP fails on listing directories with large number of files

I try to connect to an sftp server (vsftpd) on Centos server through port 22. there is no problem in connection and initial directory listing; there is also no problem if I click on a directory with less than 10 files within. but for directories…
Ahmad
  • 207
  • 1
  • 3
  • 11
3
votes
3 answers

Disadvantages to using an MTU over 1500

What disadvantages are there to set the MTU to the maximum possible value in ALL network adapters on a network (including virtual switches vmware esx)? Why do not the producers as a default? I do not understand the way to use a network card to 1500…
CSG
  • 707
  • 1
  • 11
  • 18
3
votes
4 answers

Smaller network packets vs bigger packets - confused

Some are saying that bigger packets are better to send then smaller. But in this app: http://media.pearsoncmg.com/aw/aw_kurose_network_2/applets/message/messagesegmentation.html The lower the packet size is, the smaller amount of time it needs to…
exeq
  • 33
  • 1
  • 1
  • 3
3
votes
1 answer

PIX 506E, MTU, VPN Packet Fragmentation and Shoretel IP telephone system

We have two sites, a large Southern site and a small Northern site, that have a VPN between them defined on two Cisco PIX Firewalls. Over this VPN Shoretel IP phone traffic travels as well as all other network traffic. We recently switched the…
MagicalArmchair
  • 265
  • 3
  • 10
3
votes
2 answers

seeing remote MTUs of 250 and 68. is this ever valid?

I'm seeing an ICMP storm from a mobile phone netblocks belonging to "TELEFONICA MOVILES". Periodically we will get upwards of 5 million in a few seconds, all something like this: 08:12:05.740781 IP (tos 0x0, ttl 112, id 40224, offset 0, flags…
cjp
  • 208
  • 1
  • 6
3
votes
4 answers

How to check who blocks ICMP during MTU path negotiation?

I am getting MTU problems with connections to my web host provider. The issue is that I am behind ppoe with MTU size set to 1492 which preventing me from using 'scp'. Once changing MTU from 1492 to 1500 the scp works fine however most of other…
bogumbiker
  • 87
  • 1
  • 5
3
votes
2 answers

MTU, DSL router and stalling TCP

I am discovering stalling TCP connection problem. The problem arises when I try to scp stuff from remote system from my home network. My home network is connected to internet via PPPoE (ADSL+) and everything works perfectly once working from my home…
bogumbiker
  • 87
  • 1
  • 5
3
votes
1 answer

SSH connection problems through OpenVPN tunnel (“TCP Previous segment lost”)

I have a VPN tunnel to an OpenVPN server. The VPN is a Sophos VPN which uses OpenVPN under the hood. I do not know the server configuration nor can I change the server config. My tunnel endpoint is tun on Win 10 (OpenVPN 2.4.8) and its config looks…
divB
  • 538
  • 1
  • 6
  • 22
2
votes
0 answers

Running a Dual Stack OpenVPN server: IPv6 sorta works - however, large packets appear to fail

I'm running a Dual Stack OpenVPN Server, setup according to this tutorial: https://techblog.synagila.com/2016/02/24/build-a-openvpn-server-on-ubuntu-to-provide-a-ipv6-tunnel-over-ipv4/ . As shown in the tutorial linked above, my clients are…
Freek
  • 521
  • 1
  • 4
  • 6
2
votes
0 answers

Can't ping remote host through nat on ipsec enc0 (mtu=0)

I'm up ipsec vpn to remote host. Since the remote host accepts only one ip i'm up nat for local net on enc0. Ping from ipsec host is ok: PING 172.20.162.150 (172.20.162.150): 56 data bytes 64 bytes from 172.20.162.150: icmp_seq=0 ttl=252 time=2.597…
Morry
  • 21
  • 4
1 2
3
…
9 10