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Cut-through switching – Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide User Manual

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The num parameter specifies the maximum number of routes in the IP route table. The minimum value
is 4096. The maximum value is 524288 (subject to route patterns for FSX). The default is 80000 IP
routes. For ICX 6650, the minimum value is 2048. The maximum value is 7168. The default is 5120 IP
routes.

NOTE
If you accidentally enter a value that is not within the valid range of values, the CLI will display the valid
range for you.

To increase the number of IP subnet interfaces you can configure on each port on a device running
Layer 3 code from 24 to 64, enter the following commands.

device(config)#system-max ip-subnet-port 64

device(config)#write memory

device(config)#exit

device#reload

Syntax: system-max ip-subnet-port num

The num parameter specifies the maximum number of subnet addresses per port and can be from 24 -
128. The default is 24.

Cut-through switching

Brocade ICX 6650 operates in cut-through switching mode, meaning it starts forwarding a frame even
before the whole frame has been received. The amount of time the device takes to start forwarding the
packet (referred to as the switch's latency) is on the order of a few microseconds only, regardless of the
packet size. The Table provides the latency details.

Cut-through latency

TABLE 6

Packet size in bytes 10G latency in microseconds (10G to 10G) 40G latency in microseconds(40G to 40G)

64

1.41

1.26

128

1.47

1.27

256

1.55

1.31

512

1.75

1.36

1024

1.73

1.46

1516

1.73

1.55

5000

1.73

1.66

9212

1.73

1.66

Cut-through switching

FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide

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