The board supports connecting multiple switching cards together by Daisy Chain the cards using the P21 and P22 connectors. These connectors are located beneath the shielding cover mounted to the card. The P21 connector on the first card connects to the P22 connector on the second, and the P21 connector on the second card connects to the P22 connector on the first. If more than two cards are used, then you would extend to concept to accommodate them all (P21's connect to P22's, and vice-versa).
Note: By default P22 is connected to P21 enabling a shorter connecting path between channels (factory installed).
P21 and P22 connectors for Daisy Chain connection
The following is a block diagram connecting several boards using Daisy Chain:
Block diagram connecting several boards using Daisy Chain