Bandwidth Management Page 55 of 258
•For tandem calls, the Master/Slave information is not relevant. The Master/Slave information is designed for use between two nodes only, not between three or more nodes. It makes the codec selection for tandem calls more complex and inefficient.
To solve the issues, another codec selection algorithm, not based on the unpredictable Master/Slave information, is needed. Since any change to the Master/Slave algorithm implies a change to the H.323 standard, the new codec algorithm is used for Virtual Trunk calls between Nortel equipment.
‘Best Bandwidth’ codec selection algorithm
The “Best Bandwidth” codec selection algorithm solves the issues caused by the H.323 Master/Slave algorithm. The “Best Bandwidth” algorithm selects one common codec based on two codec lists. Every time the selection is done with the same two lists, the selected codec is the same.
The “Best Bandwidth” codec decision is based on the codec type only, it does not take into account the fact that some codecs, while generally using less bandwidth, can consume more bandwidth than others at certain payload sizes.
Algorithm details
The selected codec is the type considered as the best bandwidth codec type. To know whether one codec type has better bandwidth than another, see the rule as summarized in Table 4 on page 56.
Main Office Configuration for Survivable Remote Gateway 50 Configuration Guide
