mcpd process | gtp synchronization & iquery issue.

http://support.f5.com/kb/en-us/solutions/public/13000/600/sol13690.html

Purpose
You should consider using this procedure under the following condition:

• You are experiencing BIG-IP GTM synchronization and iQuery connection issues

Description
A BIG-IP GTM synchronization group is a collection of multiple BIG-IP GTM systems that share and synchronize configuration settings. You must meet several minimum requirements in order for BIG-IP GTM synchronization group members to communicate and synchronize properly. For more information, refer to SOL13734: BIG-IP GTM synchronization group requirements.
Starting in version 11.x, the BIG-IP GTM system uses a commit_id structure, which is linked to an MCP transaction, as a timestamp when updating the configuration for a given device group. The BIG-IP GTM sync group communication flow works as follows:

• The Configuration utility or the tmsh utility communicates configuration change to the mcpd process.
  
• The mcpd process forwards the new configuration in its entirety to the local gtmd process.
• The gtmd process updates the commit_id value and writes the new configuration to the /config/bigip_gtm.conf file.
  
• The local big3d process begins advertising the updated commit_id value using heartbeat messages transmitted to all remote gtmd processes.
  
• When a remote gtmd process notices that the peer BIG-IP GTM has a newer commit_id value, the remote gtmd invokes the iqsyncer utility to pull the newer configuration.
  
• The iqsyncer utility connects to the big3d process of the BIG-IP GTM system with the newer commit_id and requests the full configuration.
  
• The big3d process connects to its mcpd process and requests the full configuration.
  
• The mcpd process passes the configuration back to the big3d process in one or more messages. The big3d process then transmits those messages back to the requesting iqsyncer utility, and iqsyncer passes the new configuration directly to its own mcpd process, which loads it into memory.
  
• Once the mcpd process receives the new configuration, it passes the configuration to its own gtmd process, which updates its timestamp with the commit_id of the source BIG-IP GTM, and writes the configuration to the /config/bigip_gtm.conf file.
  

If you are experiencing issues relating to BIG-IP GTM synchronization group communication and need to troubleshoot the issue, perform the procedures in the following Procedures section.
Symptoms
As a result of synchronization and iquery connection issues, you may encounter the following symptoms:

• BIG-IP GTM synchronization group members may have configuration discrepancies
  
• Server objects are marked as Unavailable (Red) or Unknown (Blue)
  
• Log messages report issues related to synchronization and iQuery connections