WS-X6148 & WS-X6548

• No Jumbo Frame Support
• 1MB Buffer per 8 ports (average 128KB per port)
• Not supported with newest Supervisors (VS-S720-10G & VS-SUP2T-10G)

WS-X6148A & WS-X6748

• Jumbo Frame Support
• 2.67MB or 1.3MB Buffer per port
• Supported across all Supervisors

In short, the 6148 and 6548s should only be used in low-traffic environments, with SUP32 and SUP720 (non VSS) Supervisor cards.  The 6148A and 6748 are for high-traffic environments, such as server farms