Multinode communication (remote command line and exchanges) does not work between servers with network cards with MTU>1500

Document ID : KB000085744
Last Modified Date : 30/04/2018
Show Technical Document Details
Issue:
Error Message :
The following error may appear after X minutes on the universe.log:
nodeA:
#############################################################
|ERROR|X|IO |pid=53674116.8483| u_recv_msg | recv(socket=117, bytes=5) returns error: Connection timed out
##############################################################
nodeB:
#############################################################
|ERROR|X|IO |pid=7828.768| u_recv_msg | recv(socket=1348, bytes=5) returns error
##############################################################

Patch level detected:Dollar Universe 6.2.00
Product Version: Dollar.Universe 6.2.0

Description :Multinode communication (remote cmd and exchanges) does not work when setting MTU=9000 on both network cards of both nodes.

Server A / nodeA: AIX server with MTU=9000
Server B / nodeB: Windows server with MTU=9000


When we launch from node A a command like:
uxlst atm lan node=nodeB

The command does not return anything and remains executing

The serverB never replies to the request and finishes by closing the connection after X minutes.
Environment:
OS: All
Cause:
Cause type:
Configuration
Root Cause: The issue is related to the network devices between both server A and server B that do not allow the transmission of more than 1500 bytes of data on a tcp packet.
Resolution:
Set the MTU to 1500 on the network card of the server B, you can do so via the network card settings.
Then restart Dollar Universe, communication should work fine now.


You can consult the current value via the following command:

On Windows 2003:

netsh interface ip show interface

On Windows 2008 R2:

netsh interface ipv4 show subinterfaces

On Unix:
netstat -i

Fix Status: No Fix

Additional Information:
Workaround :
N/A