Traffic Transmitted Only on the AB Plane for Linksets in a TTC Network

Overview

Setting the Loadshare Mode attribute in the Web UI may improve load balancing between links in many practical network configurations. For Japanese Networks, the Loadshare Mode value should be set to TTC AB Plane, which affects the Signaling Link Selection (SLS) load sharing algorithm by determining which Message Signal Unit (MSU) is sent to which plane.

The following is true when the TTC AB Plane is enabled:

• When two linksets properly configured to A Plane and B Plane are carrying traffic with half or more links available (normal or fully normal), the number of SLS values assigned to two available links within the same linkset do not differ by more than one.
  
  
• When one linkset is carrying traffic, the assignment of SLS values to links might not be the same because the assignment depends on the order in which the link events occur.

When each linkset has half or more links available (is normal or fully normal), the TTC AB Plane bit divides the MSUs with even SLS values through the A Plane linkset and the MSUs with odd SLS values through the B Plane linkset. However, sometimes there is a trade-off between evenly distributing traffic across available links and respecting the TTC AB Plane bit for linkset selection. These cases are handled as follows:

• If one of the linksets has less than half its links available (is quasi-normal) but the other linkset is normal or fully normal, then only the normal or fully normal linkset is used for traffic.
  
  
• If each linkset is quasi-normal, then the traffic is load balanced based on the SLS value across available links while also trying to respect the TTC AB Plane.

Procedure to Configure a Combined Linkset with Equal Route Cost

Execute the instructions in the following procedure for a combined linkset scenario.

To configure a routeset and combined linkset with equal route cost

1. Log on to the Web UI
       
2. Click MTP3
        

3. Create or select an MTP3 NA

   Tip

   For detailed information about creating and configuring an NA, refer to Configuring an Network Appearance.

4. Create a TTC NA
         
5. Create two linksets (the AB Plane Bit must be set to A for one linkset and B for the other)
   
   
6. Create three or more links in the linksets
   
   
7. Create a routeset that uses the both linksets
   
   
8. Set the LoadShare Mode of the routeset to "TTC AB Plane"
       
9. Configure routes so route cost is equal for both linksets

After configuring the routeset and linksets, you can determine the state of the linksets based on the availability of the links.

• For a Fully Normal state, bring all the links in service on both linksets.
  
  
• For a Normal state, keep half or more than half but not all of the links available in each linkset.
    
• For a Quasi-Normal state, make less than half but an equal number of links available in each linkset.