Brocade Fabric OS Administrators Guide (Supporting Fabric OS v7.3.0) - Manual (Page 32)

Example of disabling discovery
switch:admin> mstddisable
This may erase all NID entries. Are you sure? (yes, y, no, n): [no] y
Request to disable MS Topology Discovery Service in progress....
*MS Topology Discovery disabled locally.
switch:admin> mstddisable all
This may erase all NID entries. Are you sure? (yes, y, no, n): [no] y
Request to disable MS Topology Discovery Service in progress....
*MS Topology Discovery disabled locally.
*MS Topology Discovery Disable Operation Complete!!
Device login
A device can be storage, a host, or a switch. When new devices are introduced into the fabric, they
must be powered on and, if a host or storage device, connected to a switch. Switch-to-switch logins
(using the E_Port) are handled differently than storage and host logins. E_Ports exchange different
frames than the ones listed below with the Fabric Controller to access the fabric. Once storage and
host devices are powered on and connected, the following logins occur:
1. FLOGI -- Fabric Login command establishes a 24-bit address for the device logging in, and
establishes buffer-to-buffer credits and the class of service supported.
2. PLOGI -- Port Login command logs the device into the name server to register its information and
query for devices that share its zone. During the PLOGI process, information is exchanged between
the new device and the fabric. Some of the following types of information exchanges occur:
• SCR -- State Change Registration registers the device for State Change Notifications. If a
change in the fabric occurs, such as a zoning change or a change in the state of a device to
which this device has access, the device receives a Registered State Change Notification
(RSCN).
• Registration -- A device exchanges registration information with the name server.
• Query -- Devices query the name server for information about the device it can access.
Principal switch
In a fabric with multiple switches, and one inter-switch link (ISL) exists between any two switches, a
principal switch is automatically elected. The principal switch provides the following capabilities:
• Maintains time for the entire fabric. Subordinate switches synchronize their time with the principal
switch. Changes to the clock server value on the principal switch are propagated to all switches in
the fabric.
• Manages domain ID assignment within the fabric. If a switch requests a domain ID that has been
used before, the principal switch grants the same domain ID unless it is in use by another switch.
E_Port login process
An E_Port does not use a FLOGI to log in to another switch. Instead, the new switch exchanges
frames with the neighboring switch to establish that the new switch is an E_Port and that it has
information to exchange. If everything is acceptable to the neighboring switch, it replies to the new
switch with an SW_ACC (accept) frame. The initializing frame is an Exchange Link Parameters (ELP)
frame that allows an exchange of parameters between two ports, such as flow control, buffer-to-buffer
Device login
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