The WS-X4448-GB-RJ45, WS-X4548-GB-RJ45, and WS-X4548-GB-RJ45V switching modules have 48 oversubscribed ports in six groups of eight ports each:
?Ports 1, 2, 3, 4, 5,6, 7, 8
?Ports 9, 10, 11, 12, 13, 14, 15, 16
?Ports 17, 18, 19, 20, 21, 22, 23, 24
?Ports 25, 26, 27, 28, 29, 30, 31, 32
?Ports 33, 34, 35, 36, 37, 38, 39, 40
?Ports 41, 42, 43, 44, 45, 46, 47, 48
The eight ports within each group use common circuitry that effectively multiplexes the group into a single, nonblocking, full-duplex Gigabit Ethernet connection to the internal switch fabric. For each group of eight ports, frames received are buffered and sent to the common Gigabit Ethernet link to the internal switch fabric. If the amount of data received for a port begins to exceed buffer capacity, flow control sends pause frames to the remote port to temporarily stop traffic and prevent frame loss.
Note: You can disable flow control on a port if it is the only port within a group that is connected.
When transmitting, each port in the group shares the bandwidth of a Gigabit Ethernet link. However, each port operates independently so that flow control, or configuration of one port, does not block or degrade the performance of another port in that group.
When the Gigabit Ethernet switching module is not fully utilized, you can connect balancing port connections across port groupings to maximize available bandwidth. For example, with the WS-X4448-GB-RJ45 10/100/1000 switching module, you can connect ports from different groups such as ports 4, 12, 20, or 30 (in any order) before you connect ports from the same group, such as ports 1, 2, 3, 4, 5, 6, 7 and 8.