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Planning Considerations for Fibre Channel Topologies
3
McDATA Products in a SAN Environment - Planning Manual
3-28
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E_Port segmentation - When an ISL activates, the two fabric
elements exchange operating parameters to determine if they are
compatible and can join to form a single fabric. If the elements are
incompatible, the connecting E_Port at each director or switch
segments to prevent the creation of a single fabric. A segmented
link transmits only Class F traffic; the link does not transmit Class
2 or Class 3 traffic. The following conditions cause E_Ports to
segment:
— Incompatible operating parameters - Either the R_A_TOV or
E_D_TOV is inconsistent between the two fabric elements.
— Duplicate Domain_IDs - One or more Domain_ID conflicts
are detected.
— Incompatible zoning configurations - Zoning configurations
for the two fabric elements are not compatible. For an
explanation, refer to
— Build fabric protocol error - A protocol error is detected
during the process of forming the fabric.
— No principal switch - No director or switch in the fabric is
capable of becoming the principal switch.
— No response from attached switch - After a fabric is created,
each element in the fabric periodically verifies operation of all
attached switches and directors. An ISL segments if a switch
or director does not respond to a verification request.
— ELP retransmission failure timeout - A director or switch that
exhibits a hardware failure or connectivity problem cannot
transmit or receive Class F frames. The director or switch did
not receive a response to multiple exchange link parameters
(ELP) frames, did not receive a fabric login (FLOGI) frame,
and cannot join an operational fabric.
•
Fabric services and state change notifications - In a multiswitch
fabric, director-provided services such as name service, registered
state change notifications (RSCNs), and zoning are provided on a
fabric-wide basis. For example, if a fabric-attached device queries
a director or switch name server to locate all devices that support
a specified protocol, the reply includes all fabric devices that
support the protocol that are in the same zone as the requesting
device, not just devices attached to the director or switch.
Configuring
Zones.
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