> Source: [sk110351](https://support.checkpoint.com/results/sk/sk110351)

# sk110351 - Traffic latency on VSX Gateway if MTU larger than 4096 (Jumbo Frames) is configured on an interface

| Property | Value |
|----------|-------|
| Solution ID | sk110351 |
| Date Created | 2016-03-17 |
| Last Modified | 2019-07-23 |
| Technical Level | General |
| Products | Security Gateway |
| Versions | R82.10, R82, R81.20 |
| OS | Gaia |

## Symptoms

- * Traffic latency on VSX Gateway if MTU larger than 4096 (for Jumbo Frames) is configured on an interface.

* CPU cores that run CoreXL Secure Network Dispatchers (SND) are loaded at 100% CPU without any apparent cause.

* Kernel debug "`fw ctl debug -m fw + drop`" shows that CoreXL FW drops traffic with  
  `Reason: Instance is currently fully utilized`

* Output of the "`fw ctl pstat -u`" command in the context of the affected Virtual System shows large number(s) in the "`alloc non zeco skb buffers`" section.

  *Example output*:

  ```
  
  alloc zeco skb buffers:
  data size under 256: 99970298
  data size under 2048: 1399
  data size under 4096: 0
  data size above 4097: 0
  
  alloc non zeco skb buffers:
  data size under 256: 506997
  data size under 2048: 1
  data size under 4096: 0
  data size above 4097: 0 
  ```

* In some cases, it was found that the issue occurs ONLY during policy installation.

## Cause

Packets do not go through the ZeCo Buffer when MTU larger than 4096 (for Jumbo Frames) is configured on VSX interface(s) with the "`set interface `*IFNAME*` mtu `*VALUE*" command.

## Solution

This problem was fixed. The fix is included in:

* [Check Point R80.20](https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk122485)

For **other [supported](http://www.checkpoint.com/support-services/support-life-cycle-policy/index.html) versions** , [Check Point Support](http://www.checkpoint.com/support-services/contact-support/index.html) can supply a **Hotfix** .  
A Support Engineer will make sure the Hotfix is compatible with your environment before providing the Hotfix.  
For faster resolution and verification, please collect [CPInfo files](https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk92739) from the Security Management Server and Security Gateways involved in the case.

**Hotfix installation instructions:**

1. Hotfix has to be installed on ***VSX Gateway running on Gaia OS***.

   Notes:
   * In cluster environment, this procedure must be performed on *all* members of the cluster.
   * The hotfixes must be installed in the given order - 1) SecurePlatform, 2) FW1
   * The hotfixes must be uninstalled in the given order - 1) FW1, 2) SecurePlatform
2. Install the hotfix packages using Legacy CLI:

   Note: On these versions of VSX, the CPUSE does not support installation of hotfixes (refer to [sk92449](https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk92449#System requirements and limitations) - section "(2)" - "VSX Gateways").
   1. Transfer the two hotfix packages to the machine into two *separate* directories:

      * FW1 package (*fw1_wrapper_\<HOTFIX_NAME\>.tgz* ) into e.g., */path_to_FW1_fix/*
      * OS package (*SecurePlatform_\<HOTFIX_NAME\>.tgz* ) into e.g., */path_to_OS_fix/*
   2. Unpack and install the OS hotfix (must install the "OS hotfix" before the "FW1 hotfix"):

      ***\[Expert@HostName\]# cd /path_to_OS_fix/***   
      ***\[Expert@HostName\]# tar -zxvf SecurePlatform_\<HOTFIX_NAME\>.tgz***   
      ***\[Expert@HostName\]# ./SecurePlatform_\<HOTFIX_NAME\>***
      **Note:** The script will stop all of Check Point services (*cpstop*) - read the output on the screen.
   3. Do **NOT** reboot yet.

   4. Unpack and install the FW1 hotfix package (must install the "FW1 hotfix" only after the "OS hotfix"):

      ***\[Expert@HostName\]# cd /path_to_FW1_fix/***   
      ***\[Expert@HostName\]# tar -zxvf fw1_wrapper_\<HOTFIX_NAME\>.tgz***   
      ***\[Expert@HostName\]# ./fw1_wrapper_\<HOTFIX_NAME\>***
      **Note:** The script will stop all of Check Point services (*cpstop*) - read the output on the screen.
   5. Reboot the machine.

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