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Access Gateway mode in Brocade explained for beginners

I am a SAN Engineer for a leading storage vendor. The purpose of this article is to provide you a brief understanding on AG Mode in Brocade, the content is very basic and can be used as a reference.

Brocade Access Gateway is a FOS feature and it lets us configure an F port as N port. This reduces the number of domains. When an F port is configured as N port it increases the number of device ports that we can connect to a single fabric. When access gateway is configured on the switch the F ports connects as N ports on the fabric instead of E Ports. Switches in AG Mode are logically transparent to hosts and fabric. We can increase the number of hosts without increasing the switch. This simplifies configuration and management in a large fabric by reducing the number of domains and ports.

In simple terms we can call a switch in AG mode as multiplexer because it’s many to one.

The following features are not available in AG Mode:
  • FCAL
  • Fabric Manager
  • IP over FC
  • ISL Trunking
  • Extended Fabrics
  • Management Platform services
  • Name services (SNS)
  • Port Mirroring
  • SMI-S
  • Zoning
The following features are available in AG Mode
  • RABC features
  • Admin Domains
  • Advanced performance monitoring
  • Direct connection to SAN target

The following are the major difference between a Fabric OS switch in native mode and a Fabric OS switch in AG mode,
  • FOS switch in native mode is a part of the fabric and can connect only to FOS fabric only. It uses many physical ports for ISL connectivity and consumes fabric resources.

  • AG is outside the fabric, it reduces the number of switches in fabric and number of ports. We can connect switch in AG mode to any fabric, meaning it can interoperate with different typed of fabric regardless of vendor.
Ports in AG mode:
  • F Port – Fabric port that connects a host or a storage device to a switch in AG mode
  • N Port – Node port that connects a switch in AG mode to fabric as F Port.
When enabling AG mode some configuration information like zoning and others will be deleted from switch so perform a configupload to backup the configuration.

Ensure that switch is in native mode 0. To learn about various interop modes click here

#switchshow - If the interop mode is anything other than 0 change it to 0 by issuing command #interopmode 0
#switchdisable - this syntax will disable all the ports in switch and will not participate in I/O
#ag --modeenable - Now switch will reboot and come back in AG mode with default port mapping
#switchshow - We can confirm the switch mode in this command and it will also show us the ports configured as N and F ports

To disable AG Mode,
#ag --modedisable 

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