Hub and Tunnel Communications 7.x and 8.x

Document ID : KB000072944
Last Modified Date : 17/10/2018
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The following article applies to all versions of hub 7.x, and is found helpful in hub 8.x versions;  however, we do recommend upgrading to the latest version before applying any of these changes.

UIM 8.x 
Hub versions 7.x and higher
After upgrading to hub 7.x, some customers experienced instability and connectivity issues between tunneled hubs, including queue connectivity failures and frequent tunnel disconnections. The settings proscribed in this article have been found to remediate these issues and to also be applicable in improving connection stability in hub 8.x versions as well.

It is considered normal, and not necessarily a problem in and of itself, for tunnels to disconnect occasionally; hub 7.x architecture contained numerous improvements intended to reduce the impact of these minor events by ensuring that the hub and tunnels can recover quickly from such events, without any noticeable impact to the system or loss of data. However, if the tunnels are found to be disconnecting so frequently that it is causing a business impact (such as difficulty configuring probes and a barrage of tunnel/queue alarms), then the following settings may help mitigate this behavior and stabilize the connectivity.

These settings should be applied to each hub in the environment.

Edit the hub.cfg and find the <hub> section. In that section, adjust the following keys (most should exist already, but if any do not, you may add them.)
postroute_interval = 120
postroute_reply_timeout = 180
postroute_passive_timeout = 300
hub_request_timeout = 120
tunnel_hang_timeout = 300
tunnel_hang_retries = 3

On systems with very low latency and fast response between hubs, it may be beneficial to decrease tunnel_hang_timeout to 120, or even 60.

Also for improved response with the Infrastructure Manager, you can try setting the 'probe request timeout" in IM tools->options up to 60 which should improve performance (default is 10).

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