Application Delivery (ADX)

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Occasional Contributor
Posts: 5
Registered: ‎04-21-2015
Accepted Solution

Does anyone know about the command "server no-sym-session-sync"?

Hi,

 

I'm using old serverionGT with version 10.2.02gTD4.

 

And this device was configured and managed by post manger.

 

Now I'm managing it. And there is the command line configured "server no-sym-session-sync".

 

What is this command for?

 

I can't find any clue about this anywhere...

 

please, help me.

 

thanks

Contributor
Posts: 74
Registered: ‎08-18-2011

Re: Does anyone know about the command "server no-sym-session-sync"?

Hi,

This command is used to disable something called "fast session sync" which happens after the failover or a standby partner device comes up. 

In "fast session sync" a bulk syncing information related to all existing connection on active device to standby device happens so that both the box come in to same state and then from there on a normal HA information sync starts.

 

One reason for this command could be that it might be causing high CPU in some scenarios in your setup.

Hope it helps.

-Mohit Sahni
Occasional Contributor
Posts: 5
Registered: ‎04-21-2015

Re: Does anyone know about the command "server no-sym-session-sync"?

Hi, Mohit Sahni.

 

Thnanks for your comments.

 

Until failover happens, doesn't it affect anything to existing symtemtric Active-Standby pair of devices?

 

I have sevral pairs with that "fast session sync" enabled, and one pair with that "fast session sync" disabled.

 

And all of them are placed in DSR structure.

 

But the only pair without "fast session sync" shows very different "CurrConn" statistics of "show server sessions" and "show server virtual" results.

 

I was wondered if the command "server no-sym-session-sync" affect this issue.

 

If it doesn't affect as you said, I sould bring it to tech support team.

 

Thanks.

Contributor
Posts: 74
Registered: ‎08-18-2011

Re: Does anyone know about the command "server no-sym-session-sync"?

Hi,

I think difference in connections may be due to even the normal session not being sync'd. What I have seen is that normally for UDP services the sync of connections from Active to standby is disabled in configuration as they are just one request and response. Check your config is the normal session sync is also disabled. (Look for commands with word sync in the keyword.)

 

-Mohit Sahni
Occasional Contributor
Posts: 5
Registered: ‎04-21-2015

Re: Does anyone know about the command "server no-sym-session-sync"?

Do you mean the command "session-sync" at the server port profile?

 

I attatched some of my configuration, and the result of "show server virtual".

 

Thanks for your help.

 

 

this is a configuration.

------------------------------------

server force-delete

server no-sym-session-sync
server no-slow-start
server keepalive-fin
server tcp-age 60

 

server port 16000
session-sync
tcp keepalive 2 4
tcp l4-check-only

 

server port 17000
session-sync
tcp keepalive 2 4
tcp l4-check-only

 

server port 18000
session-sync
tcp keepalive 2 4
tcp l4-check-only

------------------------------------

 

With those conifg, does normal session sync should happen?

 

And, the results of "show server virtual" of Active and Standby devices are below

 

For Active device,

Port State Sticky Concur Proxy DSR CurConn TotConn PeakConn
---- ----- ------ ------ ----- --- ------- ------- --------

16000 enabled NO NO NO YES 30 47291 60
17000 enabled NO NO NO YES 55 293905 290
18000 enabled NO NO NO YES 30 47294 33

 

For Standby device,

Port State Sticky Concur Proxy DSR CurConn TotConn PeakConn
---- ----- ------ ------ ----- --- ------- ------- --------
16000 enabled NO NO NO YES 69 73 69
17000 enabled NO NO NO YES 1791 1795 1791
18000 enabled NO NO NO YES 69 73 69

Contributor
Posts: 74
Registered: ‎08-18-2011

Re: Does anyone know about the command "server no-sym-session-sync"?

Having different numbers does not mean that something is wrong for sure, it may depend upon different features you are using but if you have doubt you can talk to the support.

-Mohit Sahni
Occasional Contributor
Posts: 5
Registered: ‎04-21-2015

Re: Does anyone know about the command "server no-sym-session-sync"?

HI, Mohit Sahni

 

As you mentioned about "fast session sync",

 

I have seached that function at the "ServerIron_10202_SLBguide.pdf".

 

But it said, the "fast session sync" can't be disabled. While the older version SLBguide doesn't mention about it.

 

Does that command "server no-sym-session-sync" have any effect in OS version 10.2.02?

 

below is the description about it at the "ServerIron_10202_SLBguide.pdf".

---------------------------

Fast session synchronization is enabled by default. There are no CLI commands to enable or disable this feature.

---------------------------

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