3.9.2. PMA and PCS Bonding
For PMA bonding, either x6/xN or PLL feedback compensation bonding is used. For PCS bonding, some of the PCS control signals within the bonded group are skew aligned using dedicated hardware inside the PCS.
For PMA and PCS bonding, the concept of master and slave channels is used. One PCS channel in the bonded group is selected as the master channel and all others are slave channels. To ensure that all channels start transmitting data at the same time and in the same state, the master channel generates a start condition. This condition is transmitted to all slave channels. The signal distribution of this start condition incurs a two parallel clock cycle delay. Because this signal travels sequentially through each PCS channel, this delay is added per channel. The start condition used by each slave channel is delay compensated based on the slave channel's distance from the master channel. This results in all channels starting on the same clock cycle.
The transceiver PHY IP automatically selects the center channel to be the master PCS channel. This minimizes the total starting delay for the bonded group. For PLL feedback compensation bonding up to all channels on one side can be bonded if the master PCS channel is placed in the center of the bonded group.
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