ARP table size increase is not surviving the reboot

[Vladimir]

Has anyone run in to it after the upgrade to R80.20?

[HeikoAnkenbrand]

Hi @Vladimir 

This doesn't work after a reboot:

> set arp table cache-size 4096
> save config

A quick and dirty solution:-)

Add the following to the start script until the problem is solved by Check Point TAC!

echo 4096 > /proc/sys/net/ipv4/neigh/default/gc_thresh3

[Vladimir]

Thank you @HeikoAnkenbrand !

[HeikoAnkenbrand]

Still from the good old SPLAT times under R65:-)

[Vladimir]

$#!!, now I remember running into it years ago 🙂

[HeikoAnkenbrand]

Still works today. Shouldn't read the R&D team:-)

[Vladimir]

Heiko, in the context of VSX, would this be a global setting for the entire VSX box, or is there a way to do it for individual VS?

[PhoneBoy]

Looks like a global setting.

[Vladimir]

Well, if this is issue still persists to date, perhaps sk43772 should be rewritten, as it is still explicitly states:

Gaia Portal / Gaia Clish will override any settings placed in the /etc/sysctl.conf file. Any changes made to this file do not take effect after a reboot.

To configure threshold level for ARP cache on Gaia OS:

Note: Gaia OS accepts maximal threshold level of 16384.

• In Gaia Portal:

  Go to Network Management section - click on ARP page - go to section ARP Table Settings section - enter the desired value in Maximum Entries field.

• In Gaia Clish:

  HostName> set arp table cache-size <Number_of_Entries>
  HostName> save config

To check the current threshold level for ARP cache on Gaia OS::

• In Gaia Clish:

  HostName> show arp table cache-size

• In Expert mode:

  [Expert@HostName:0]# dbget ip:arp:cache_size

Notes:

• Once set in the Gaia Portal / Gaia Clish, the settings will survive a reboot.
• Settings are applies immediately (reboot, restart of any services, policy installation are not required)

The Maximum Entries value in the Gaia Portal corresponds to gc_thresh3 parameter in Linux kernel.

Note: In Gaia OS, the value of gc_thresh1 and the value of gc_thresh2 are automatically determined by the value of gc_thresh3 value:

• value of gc_thresh1 is 1/8 the value of gc_thresh3
• value of gc_thresh2 is 1/2 the value of gc_thresh3

[JozkoMrkvicka · Accepted solution]

We are using /etc/rc.local file for similar cases. In this case, here is one-time command which will make sure that parameter will survive a reboot:

# echo "echo 4096 > /proc/sys/net/ipv4/neigh/default/gc_thresh3" >> /etc/rc.local

 But be aware that the current threshold level for ARP cache on Gaia OS:

• In Gaia Clish:

  HostName> show arp table cache-size

• In Expert mode:

  [Expert@HostName:0]# dbget ip:arp:cache_size

Will still give you original value configured via clish command (not that one set via echo).

So maybe the better way would be to use bash/clish command:

# echo "clish -c 'set arp table cache-size 4096'" >> /etc/rc.local

[HeikoAnkenbrand]

Hi @JozkoMrkvicka 

This is a very nice solution:

# echo "clish -c 'set arp table cache-size 4096'" >> /etc/rc.local

 Gives me the idea to more dirty hacks

[Itaiw]

Hi @Vladimir 

Using the  following clish commands to change the arp table size and save the configuration should survive after reboot (and did survive in my tests)

> set arp table cache-size 4096
> save config

Please open a technical service request to CeckPoint support to investigate the problem on your machine.

[Brian_Deutmeyer]

How many arp entries can my table hold if my size is 4096?  I'm unsure if this maps 1 to 1, like one arp entry means 1 spot from 4096 (4096 - 1 = 4095 arp entries left)?

[Timothy_Hall]

Yes it is a one-to-one mapping, the 4096 corresponds to a variable called gc_thresh3 which specifies the hard maximum of IP to MAC address mappings in the table.  gc_thresh2is typically 1/2 of gc_thresh3 and specifies when more aggressive garbage collection starts in an attempt to free up table entries and avoid a "Neighbour table overflow" condition.  This situation can impact performance and was covered on pages 66-70 of my "Max Power" book.

[Brian_Deutmeyer]

Perfect!  I just read the pages (2nd edition) and it was helpful.  Thanks again.