Network OS Administration Guide

Supporting Network OS 6.0.1a

Part Number: 53-1003768-04

Brocade trunks

Network OS 4.0.0 and later supports Brocade trunks (hardware-based link aggregation groups, or LAGs). These LAGs are dynamically formed between two adjacent switches. The trunk formation is controlled by the same Fibre Channel Trunking protocol that controls the trunk formation on FC switches. As such, it does not require user intervention or configuration except enabling or disabling, which instructs the switch software to form a trunk at the global level or not. All ISL ports connected to the same neighbor Brocade switch will attempt to form a trunk. Refer to Enabling a fabric trunk for instructions.

Port groups have been established on supported standalone switches and on line cards in chassis systems for trunking. For a successful trunk formation, all ports on the local switch must be part of the same port group and must be configured at the same speed. Following are the number of ports allowed per trunk from port groups in supported platforms. For details on how port groups are arranged on these platforms, refer to the switch or chassis system Hardware Reference Manual.

  • VDX 8770 switches - up to six port groups of eight ports each per blade (1 , 10, or 40 GbE)
  • VDX 6740 switches - up to 16 ports per trunk
    If connections are made to 16 different switches, only eight ports will be trunk ports while the other eight ports will be normal ISL ports.
  • VDX 6940-36Q switches - up to three ports per trunk
  • VDX 2740 and VDX 2746 - up to 16 ports per trunk
  • 48x10 GbE line card - up to eight ports per trunk
  • 48x10G-T line card - up to 16 ports per trunk
  • 12x40 GbE line card - up to two 40-GbE ports are allowed per trunk, and these ports must be configured in breakout mode
  • 27x40 GbE line card - up to two 40-GbE ports are allowed per trunk, and these ports must be configured in breakout mode. Note that breakout mode is only allowed on the first two ports in port groups that are configured in Performance operating mode. Refer to the Brocade 8770 Hardware Reference Manual for more information on line card operating modes.

The following additional rules apply to Brocade trunks:

  • On Brocade VDX 6740 switches, low-volume traffic below certain thresholds may not be evenly distributed on all links. This threshold can be as low as 64 K.
  • The trunk is turned on by default.
  • Trunks are not supported between the Brocade 8000 and the Brocade VDX 8770.