Latency
=======

Transaction Processing
----------------------

Purpose
.......

Transactions should not be run by nodes over a high latency network, if possible.

Procedure
.........

1. Log in on any unified node (multinode unified topology) / application node (modular cluster topology).
2. Run the following for all the other nodes:

   **diag ping <IP>**
3. If any of the average round trip time is higher than 10ms,
   it is recommended that the nodes in the secondary DC should have
   ``voss workers`` set to 0 on version 11.5.3 and later, or the
   command **app stop voss-queue** is run on older versions.

.. note::

   For software versions *pre* 11.5.3, the **app stop voss-queue**
   command needs to be run after every service restart or server reboot.

UC Apps Latency
---------------

Purpose
.......

Latency between unified nodes and UC apps impacts overall provisioning times
against the UC apps. This check is done as part of diagnosis of provisioning
performance problems.

Procedure
.........
For each data center:

1. Log in on any unified node (multinode unified topology) / application node (modular cluster topology).
2. Run the following for all the UC apps under investigation:

   **diag ping <IP>**
3. Record the output and share results with VOSS L2.