Default Switching Mode

All platforms use store-and-forward by default. The platforms are also capable of supporting cut-through forwarding to reduce latency. Store-and-forward switching requires the complete receipt of a packet prior to transmitting it out the interface. The packet is stored in its entirety in packet memory and can be validated via the frame CRC by the switch prior to forwarding it to the next hop.

Cut-through switching allows the switch to begin transmitting a packet before its entire contents have been received thereby reducing the overall forwarding latency for large packet sizes.

Cut-through forwarding mode is supported only on 100G ports on the ExtremeSwitching X695 series switch.

The following limitations apply to the cut-through switching feature:
In some circumstances, store-and-forward is automatically used. Following are examples: