Application Acceleration
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Tunnel drop and impact on dictionnary

‎12-04-2008 04:55 AM

Hi,

 

Let's imagine compression tunnel brakes due to issue on the WAN. 

 

What's the impact on the dictionnary ? Does it depend how long the tunnel is broken or not ? Does it depend if devices are WX or WXC ? 

 

Last one: how often will WX/WXC try to re-establish tunnel ? every minute ? until we reach registration time-out (24h by default) ? 

 

thanks!!

2 REPLIES 2
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Re: Tunnel drop and impact on dictionnary

[ Edited ]
‎12-06-2008 12:46 PM

When a tunnel drops, the dictionary is preserved until you hit the disconnect timer, then it is cleaned out so a quick bounce of the tunnel due to network issues will not clean the dictionary out.

 

 

 

 

Heartbeat Timer:

By default, keep-alive packets or “heartbeats” are sent every 5 seconds to confirm the operability of the other WXC's devices in the community. To change the heartbeat frequency:

config reduction set heartbeat-frequency <1-300>
commit

Note: All WXC devices in the same community must have the same heartbeat frequency.


Passthough and Disconnect (Tunnels with only Reduction enabled):
By default, if a remote endpoint fails to respond to 4 consecutive heartbeats, the local device stops reducing data for the remote device (passthrough mode). If 10 consecutive heartbeats get no response, the reduction tunnel to the remote device is disabled.

To change the number of consecutive missed heartbeats that stops data reduction and disconnects the tunnel:

config reduction set heartbeat-misses passthru <number | default> disconnect <number | default>
commit

Passthough and Disconnect (Tunnels with NSM, AFP, or FEC enabled):
By default, when AFP or FEC is enabled for a remote endpoint, the local device stops reducing data for the remote device if it fails to respond to 15 consecutive heartbeats (passthrough mode). If 30 consecutive heartbeats get no response, the reduction tunnel to the remote device is disabled.

To change the number of consecutive missed heartbeats that stop data reduction and disconnect the tunnel:

config acceleration set heartbeat-misses passthru <number | default> disconnect <number | default>
commit

Tunnel Reestablishment:
By default, a tunnel attempts to reestablish its connections every 3 minutes. The default behavior is for a WXC to try to setup a tunnel every 3 minutes for the first 15 minutes, then every 15 minutes for the next hour, and finally every 24 hours indefinitely.

The following command will force a WXC to try and establish its tunnels every 3 minutes indefinitely.

 

config reduction set retry-backoff <on | off> [default on]
commit

The following command will force a WXC to try and establish its tunnels using the specified frequency (in minutes).

config reduction set retry-frequency <1- 5 minutes> [default 3]
commit

Note: If non-default, retry-backoff is automatically disabled.

Message Edited by DannyJ on 12-06-2008 08:47 PM
Danny Jump
Technical Marketing Manager - Access and Acceleration Business Unit
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Application Acceleration

Re: Tunnel drop and impact on dictionnary

‎03-19-2009 03:24 AM

If you are talking about the NSC dictionary, the NSC data is written to the disk in 64MBytes chunks by design, to avoid slowdown due to frequent disc write access.

 

So you would loose up to 64MB of dictionary data that might be in the memory and not yet written to the disk. The rest will be saved in the NSC dictionary on the HDD.