In this section:
The following section is only applicable to the DSC Platform.
The scenarios described in this section, override the configuration of traffic transmitted on the AB Plane for a linkset (refer to Traffic Transmitted Only on the AB Plane for Linksets in a TTC Network).
The purpose of the feature is to provide traffic load sharing for network configurations where Telecommunication Technology Committee (TTC) AB Plane Loadshsaring is defined for a properly configured combined linkset in a routeset (with AB Plane Bit properly set for each linkset - one is A the other is B) or a routeset that is sending traffic over only one route.
A properly configured combined linkset for this feature refers to
It is assumed that two or more links are provisioned in each linkset.
The following two linkset configuration scenarios are supported for properly configured combined TTC linksets:
combined linkset where less than half of the links are available in one linkset, but half or more of the links are available in the other linkset. For this scenario, the two linksets must be configured as one A Plane and one B Plane linksets (for related procedure, see Combined linkset where less than half of the links are available in one linkset, but half or more of the links are available in the other linkset)
OR
the routeset contains only one linkset (see The routeset contains only one linkset)
In a TTC AB Plane Load Share mode Routeset, where less than half of the links in each linkset are available (referred to as Quasi-Normal/Quasi-Normal or combined linkset scenario; for related procedure, see To configure a combined linkset scenario for this feature).
In scenario 1, MSUs must be sent across one linkset for instances (a, b, c, and d). MSUs with Signaling Link Selection (SLS) values that have the same Link Selection Number (LSN) value must be sent through the same link.
In scenario 2, the AB Plane is respected as long as this configuration does not further unbalance traffic. Some MSUs might not be sent through their corresponding plane. For these MSUs, they must be send across the same link used to send the MSU with the same LSN value (but different AB Plane Bit).
This feature complements the following two features:
For more information about these two features, refer to Configuring the A and B Plane Attribute in a TTC Network and Traffic Transmitted Only on the AB Plane for Linksets in a TTC Network, respectively.
According to TTC standard (JT Q.704 ), in the single linkset scenario, the LSN value should be used to select the outgoing link onto which an MSU will be sent. Therefore, two SLS values with the same LSN value must be sent through the same link .
In NTT, the SLS is 5 bits and different parts of the SLS are considered relevant depending on the type of the outgoing linkset (STP to SEP, STP to STP, etc). Because the SLS in TTC is 4 bits, the NTT procedures cannot be applied directly. In particular, the 4 bit SLS in TTC is always considered to be a 3 bit LSN and a 1 bit A/B plane bit, regardless of the function of the outgoing linkset.
According to Nippon Telegraph and Telephone Corporation (NTT) documentation, in a combined linkset scenario where both linksets are in the Quasi-Normal state, typically the AB Plane Bit is respected and the MSUs are sent over the correct plane as long this action does not further unbalance traffic across all the available links. Two SLS values with the same LSN value must be sent through the same link in the case where the AB Plane Bit is not enforced.
Execute the instructions in the following procedure to configure one of the options for single linkset scenario for this feature.
Create or select an MTP3 NA.
For detailed information about creating and configuring an NA, refer to Configuring an Network Appearance.
Execute the instructions in the following procedure for combined linkset scenario (can be referred to as Quasi-Normal/Quasi-Normal).
Make more than half the links in both linksets go unavailable (each linkset is in the Quasi-Normal state).