High Speed Flow Control; Symmetric Mode; Asymmetric Mode; Enabling Flow Control Using Acli - Avaya 3500 series Getting Started

Managing Ethernet ports using ACLI

High speed flow control

The high speed flow control feature lets you control traffic and avoid congestion on the gigabit
full-duplex link. If the receive port buffer becomes full, the Ethernet Routing Switch 3500 Series
issues a flow-control signal to the device at the other end of the link to suspend transmission.
When the receive buffer is no longer full, the switch issues a signal to resume the transmission.
You can choose Symmetric or Asymmetric flow control mode.
High speed flow control cannot be configured unless you set Autonegotiation to Disabled on
the port and the speed/duplex is at 1000/full.
Two high speed flow control modes are available:

Symmetric mode

This mode lets both GBIC port and its link partner to send flow control pause frames to each
other.
When a pause frame is received (by either the GBIC port or its link partner), the port suspends
transmission of frames for a number of slot times specified in the control frame or until a pause-
release control frame is received. Both devices on the link must support this mode when it is
selected.

Asymmetric mode

This mode lets the link partner send flow control pause frames to the GBIC port. When a pause
frame is received, the receiving port suspends transmission of frames for a number of slot
times specified in the control frame or until a pause-release control frame is received.
In this mode, the GBIC port is disabled from transmitting pause frames to its link partner. Use
this mode when the GBIC port is connected to a buffered repeater device.
You can choose a flow control mode with ACLI commands.

Enabling flow control using ACLI

If you use a Gigabit Ethernet with the Ethernet Routing Switch 3500 Series, you control traffic
on this port using the flowcontrol command.
Before you begin
• Autonegotiation must be set to Disabled on the port.
• The speed/duplex must be 1000/full.
74 Getting Started
Comments? infodev@avaya.com
March 2013