Brocade Communications Systems manual Interpacket Gap IPG on a Brocade ICX 6650 switch

Basic port parameter configuration 2

Enabling and disabling symmetric flow control

By default, symmetric flow control is disabled and tail drop mode is enabled. However, because flow control is enabled by default on all full-duplex ports, these ports will always honor received 802.3x Pause frames, whether or not symmetric flow control is enabled.

To enable symmetric flow control globally on all full-duplex data ports of a standalone unit, enter the symmetric-flow-control enable command.

Brocade(config)# symmetric-flow-control enable

Syntax: [no] symmetric-flow-control enable

To disable symmetric flow control once it has been enabled, use the no form of the command.

Interpacket Gap (IPG) on a Brocade ICX 6650 switch

You can configure an IPG for each port. An IPG is a configurable time delay between successive data packets. You can configure an IPG with a range from 48-120 bit times in multiples of 8, with a default of 96. The IPG may be set from either the interface configuration level or the multiple interface level. You configure IPG at the interface level on 1 Gbps ports only. The command you use depends on the interface type on which IPG is being configured.

The default interpacket gap is 96 bits-time, which is 9.6 microseconds for 10 Mbps Ethernet, 960 nanoseconds for 100 Mbps Ethernet, 96 nanoseconds for 1 Gbps Ethernet, and 9.6 nanoseconds for 10 Gbps Ethernet.

IPG configuration notes

•IPG configuration commands are based on "port regions". All ports within the same port region should have the same IPG configuration. If a port region contains two or more ports, changes to the IPG configuration for one port are applied to all ports in the same port region. When you enter a value for IPG, the CLI displays the ports to which the IPG configuration is applied.

Example

Brocade(config-if-e10000-1/2/1)# ipg 48

Syntax: ipg <decimal>

The <decimal> variable specifies a range between 48 to 120, in multiples of 8.

•When you enter a value for IPG, the device applies the closest valid IPG value for the port mode to the interface. For example, if you specify 120 for a 1 Gbps Ethernet port in 1 Gbps mode, the device assigns 112 as the closest valid IPG value to program into hardware.

•When an IPG is applied to a trunk group, it applies to all ports in the trunk group. When you are creating a new trunk group, the IPG setting on the primary port is automatically applied to the secondary ports.

•This feature is supported on 10/100/1000M ports.

Changing the Gbps fiber negotiation mode

The globally configured Gbps negotiation mode is the default mode for all Gbps fiber ports. You can override the globally configured default and set individual ports to the following:

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