Commands to enable or disable Jumbo Frame Support on the PacketShaper S-Series

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Article ID: 170888

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Updated On:

Products

PacketShaper S-Series

Issue/Introduction

You want to enable or disable Jumbo Frame Support on the PacketShaper S-Series.

Resolution

By default, the PacketShaper S-Series NIC driver supports standard frames that have a Maximum Transmission Unit (MTU) of 1500 bytes and will drop packets that exceed this size. The PacketShaper S-Series NIC driver now supports Jumbo Frames that have a Maximum Transmission Unit (MTU) of 9000 bytes. 

To enable Jumbo Frames support (MTU = 9000 bytes) on your PacktShaper S-Series:

  1. Run the following command:
    setup variable enableJumboFrame 1
  2. You must change the tcpMssInbound and tcpMssOutbound system variables from their default settings of 1460 bytes to 8960 bytes in order to equal the payload size of Jumbo Frames (MTU = 9000 bytes) by running the following commands:
    setup variable tcpMssInbound 8960
    setup variable tcpMssOutbound 8960
    ​

​To disable Jumbo Frames and default the PacketShaper to Standard Frames support (MTU = 1500 bytes).

  1. Run the following command:
    setup variable enableJumboFrame 0
  2. You must ensure the tcpMssInbound and tcpMssOutbound system variables are changed back to their default settings of 1460 bytes in order to equal the payload size of Standard Frames (MTU = 1500 bytes) by running the following commands:
    setup variable tcpMssInbound 1460
    setup variable tcpMssOutbound 1460
    ​

Some PacketShaper S-Series appliances may require a memory grade, available directly from Symantec.  Use the command version verbose to confirm the amount of memory installed on your PacketShaper S-Series.  See below for the minimum memory requirements for your PacketShaper S-Series to support the Jumbo Frames feature:

  • PacketShaper S200 - 16GB
  • PacketShaper S400 - 32GB
  • PacketShaper S500 - 64GB

Note: The Jumbo Frames feature is only available on PacketShaper S-Series software image versions 11.7.1.1 and later.   The setup variable enableJumboFrame command is not supported on PacketShaper S-Series software image versions earlier than 11.7.1.1.