In a Clos data center network, scaling the available bandwidth to support more east-west traffic can be effectively achieved by either adding more leaf devices (A) or more spine devices (C). Adding leaf devices increases the total number of endpoints in the network, thereby providing additional paths and bandwidth for east-west traffic. Similarly, adding spine devices increases the interconnectivity within the network, offering more paths for traffic to flow through, which helps in handling higher volumes of east-west traffic. Both approaches work towards enhancing the overall capacity and efficiency of the network. Reference:
Juniper Networks - Understanding Clos Networks
Juniper Networks - Data Center Network Design Considerations