EMC DS-4900B Hardware Reference Manual page 72

DS-4900B Specifications
Table 6-4
Specification
Aggregate switch I/O bandwidth
Port-to-port latency
6-8
EMC Connectrix B Series DS-4900B Version 5.1 Hardware Reference Manual
General specifications (continued)
Description
512 Gbit/sec if all 64 ports are running at 4 Gbit/sec, full duplex
Less than 2 microseconds with no contention (destination port is free)