Slow printing of documents when jumbo packets are enabled on the network

  • 7010535
  • 30-Jul-2012
  • 30-Jul-2012

Environment

Novell iPrint for Linux
Novell Open Enterprise Server 11 (OES 11) Linux
Novell Open Enterprise Server 2 (OES 2) Linux
ESX/ESXi 4.1 Update 2 and earlier
 

 

Situation

Slow printing of documents when jumbo packets are enabled on the network.
 
Poor TCP performance may occur in Linux virtual machines with LRO enabled in VMware.
 
Spooling of iPrint jobs is slow.

Resolution

Large Receive Offload (LRO) functionality is enabled by default on VMXNET 2 (Enhanced) and VMXNET 3 devices. In some scenarios, Linux TCP/IP stack performs poorly when handling LRO-generated packets. As a result, having Large Receive Offload enabled for these devices in a virtual machine running a Linux guest operating system can cause poor TCP performance.
 
Workaround:
By enabling tcpdump on the server the Network card is put in promiscuous mode which appears to increase the rate at which the print job is received.  As a workaround run tcpdump and only log information for a port not being used.
Do the following:
  1. Open up a terminal as root.
  2. Type "tcpdump port 12"
Resolution:
 
Follow the instructions found in the VMware document titled "Poor TCP performance may occur in Linux virtual machines with LRO enabled".

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