> Source: [sk181996](https://support.checkpoint.com/results/sk/sk181996)

# sk181996 - Traffic outages may occur because of high utilization of CPU cores that run CoreXL SND instances

| Property | Value |
|----------|-------|
| Solution ID | sk181996 |
| Date Created | 2024-02-15 |
| Last Modified | 2025-02-17 |
| Technical Level | General |
| Products | Security Gateway |
| Versions | R81.20 |
| OS | Gaia |

## Symptoms

- * Random traffic outage through a Security Gateway / Cluster / VSX Virtual System.  
  High rate of RX-Drops even though we see low rate of throughput.

* Output of the "`top`" command on the Security Gateway / Cluster Member during the traffic outage shows very high utilization of CPU cores that run the CoreXL SND instances.

* Output of the "`perf top -C `" command on the Security Gateway / Cluster Member during the traffic outage shows that the function responsible for the high CPU utilization is "`fwmultik_do_seq_on_packet`".


  Example:

  ```
  
  61.11% snd          [kernel.kallsyms] [k] fwmultik_do_seq_on_packet  
  26.99% ksoftirqd/37 [kernel.kallsyms] [k] fwmultik_do_seq_on_packet
  ```

* The `$FWDIR/log/fwk.elg` file (in VSX mode) or `/var/log/messages` file (in Gateway mode) on the Security Gateway / Cluster Member contains this line repeatedly:

  `fwmultik_do_sequence_accounting_on_entry: sequence xxxxxxxx out of order (last handled sequence 4294967295)`

## Cause

Utilization of CPU cores that run CoreXL SND instances may reach high levels when there are connections with a long duration that transfer large traffic volume.

## Solution

This problem was fixed. The fix is included in:

* [Check Point R82](https://support.checkpoint.com/results/sk/sk181127)
* [Jumbo Hotfix Accumulator for R81.20](https://sc1.checkpoint.com/documents/Jumbo_HFA/R81.20/Default.htm) starting from Take 70

If you choose not to upgrade, Check Point can supply a **Hotfix** . [Contact Check Point Support](https://www.checkpoint.com/support-services/.contact-support/) to get a Hotfix for this issue.  
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](http://supportcontent.checkpoint.com/solutions?id=sk92739) from the Security Management Server and Security Gateways involved in the case.

**Hotfix installation instructions:**   
Refer to [sk168597 - How to install a Hotfix](https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk168597).

<br />

This immediate **workaround** is available:

1. Connect to the command line on the Security Gateway / each Cluster Member / Security Group.

2. Log in to the Expert mode.

3. Configure the value of the kernel parameter "`fwmultik_validate_sequence` " to 0 (zero):

   **Note** - This kernel parameter controls whether to print additional information during a kernel debug. It has no effect on the performance or security.

   **Important Note - Before you install the hotfix for this issue, permanently configure the value of the kernel parameter "`fwmultik_validate_sequence`" to 1 (one).**

   |---------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|
   | Deployment                                                    | Temporary Configuration                                                                                                           | Permanent Configuration                                                                                                                                           |
   | Security Gateway, ClusterXL                                   | In Gaia Clish, or in the Expert mode: `fw ctl set int fwmultik_validate_sequence 0`                                               | In Gaia Clish, or in the Expert mode: `fw ctl set -f int fwmultik_validate_sequence 0`                                                                            |
   | Security Group in Maestro, Security Group on Scalable Chassis | In Gaia gClish: `fw ctl set int fwmultik_validate_sequence 0` In the Expert mode: `g_fw ctl set int fwmultik_validate_sequence 0` | In Gaia gClish: `fw ctl set -f int fwmultik_validate_sequence 0` In the Expert mode: `g_update_conf_file $FWDIR/modules/fwkern.conf fwmultik_validate_sequence=0` |

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