Xen project Mailing List

Eric Wrote:

"Steven,

Why would you want to change the MTU, som applications won't like a non 
standard (<1500) MTU, we use a MTU of 1504 on our 802.1q interface (an 
e1000)
in Dom0 to bridge vlan interfaces to domU and preserve a 1500 byte mtu, 
mtu 1504 should work without setting it as the kernel support 802.1q 
framing
(1500 byte + 4 byte vlan tag).

Erik"


My Reply:

Erik: 

The reason I am changing the MTU setting is that I am unable to properly communicate between 
domU and dom0 do to packet truncation. These errors show up when diagnostic logging is set to maximum.

This is apparently a known issue with Xen from what I was told.

Also, my internet connection is now about 6 times as fast with 1/3 the latency that it
used to have. I use a cable internet connection.

Please see this article

http://www.webservertalk.com/archive236-2004-5-193783.html

Bellow are the steps I used to setup FreeNX /SSH -Y--Xnest setup.
This problem is cured by changing my MTU size.
_______________________________________________
I tried to get FreeNX working and was getting sigterm 15 error. Which noone was able to help with. I decided to troubleshoot the problem by just connecting thru SSH -Y connection from dom0 to domU. The image for the guest was created in qemu and the system partition was migrated to a raw partition for use with Xen. I have spent two weeks troubleshooting it and no luck. I have reinstalled openssh and its dependents on both domU and dom0 and still no luck at all. I am at my wits end with this problem. I have spent about 12 hours with people from the #linuxhelp #fedora from freenode and irc.oftc.. and noone has been able to help.. They think its a Xen issue but I am not sure. Next I was going to try and get it working from dom0 to the qemu image to see if it made a difference.

Here is the details

trying to setup xnest session to remotely launch xterm (later on I would like to get gnome working remotely)

on the server side I have IP! address 192.168.15.101
on the client side I have IP address 192.168.15.100

I am not using DNS

I launch the SSHD with the command /usr/sbin/sshd -d -p 1236

It says

debug1: sshd version OpenSSH_4.2p1
debug1: read PEM private key don! e: type RSA
debug1: private host key: #0 type 1 RSA
debug1: read PEM private key done: type DSA
debug1: private host key: #1 type 2 DSA
debug1: rexec_argv[0]='/usr/sbin/sshd'
debug1: rexec_argv[1]='-d'
debug1: rexec_argv[2]='-p'
debug1: rexec_argv[3]='1236'
debug1: Bind to port 1236 on 192.168.15.101.
Server listening on 192.168.15.101 port 1236

On the client I issue xhost +

It says

access control disabled, clients can connect from any host

I type Xterm

an Xterm session starts

In the Xterm session I type

Xnest :1 -ac &
It informs me
Could not init font path element /usr/X11R6/lib/X11/fonts/TT! F/, removing from list!
Could not init font path element /usr/X11R6/lib/X11/fonts/CID/, removing from list!

I hit <enter>

A prompt appears

I type ssh -Xvvv -p 1236 hikenboot@xxxxxxxxxxxxxx

It tells me

It says a bunch ! of stuff
then It says
debug3:authmethod_is_enabled password
debug1: Next authentication method: password
hieknboot@xxxxxxxxxxxxxx's password:

I type my password

It says a bunch of stuff then it says
debug1: Recieved SIGCHLD.

and then a prompt appears

I type export DISPLAY=192.168.15.100:1

then I type
xterm

the last lines on the server say

debug1: session_new: session 0
debug1: session_open: channel 0
debug1: session_open: session 0: link with channel 0
debug1: server_input_channel_open: confirm session
debug1: server_input_channel_req: channel 0 request x11-req reply 0
debug1: session_by_channel: session ! 0 channel 0
debug1: session_input_channel_req: session 0 req x11-req
debug1: channel 1: new [X11 inet listener]
debug1: channel 2: new [X11 inet listener]
debug1: server_input_channel_req: channel 0 request pty-req reply 0
debug1: session_by_channel! : session 0 channel 0
debug1: session_input_channel_req: session 0 req pty-req
debug1: Allocating pty.
debug1: session_new: init
debug1: session_new: session 0
debug1: session_pty_req: session 0 alloc /dev/pts/1
debug1: server_input_channel_req: channel 0 request shell reply 0
debug1: session_by_channel: session 0 channel 0
debug1: session_input_channel_req: session 0 req shell
debug1: Setting controlling tty using TIOCSCTTY.

on the clients xterm /xnest session it just hangs!

thats it..

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[Xen-users] Re: MTU-1492 Permenent Setting for Xen Specific Interfaces