HP Surestore 64 - Director Switch Installation Manual page 26

Overview
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Port segmentation—When an ISL activates, directors exchange operating
parameters to determine if they are compatible and can join to form a single
fabric. If they are incompatible, the connecting E_Port at each director
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 ports to segment:
— Incompatible operating parameters—Either the resource allocation
timeout value (R_A_TOV) or error detect timeout value (E_D_TOV) is
inconsistent between directors. To prevent E_Port segmentation, the same
E_D_TOV and R_A_TOV must be specified for each director.
— Duplicate domain IDs—One or more domain ID conflicts are detected.
— Incompatible zoning configurations—Zoning configurations for the
directors are not compatible.
— Build fabric protocol error—A protocol error is detected during the
process of forming the fabric.
— No principal switch—No director in the fabric is capable of becoming
the principal switch.
— No response from attached switch—After a fabric is created, each
director 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 that exhibits a
hardware failure or connectivity problem cannot transmit or receive Class
F frames. The director did not receive a response to multiple exchange
link protocol (ELP) frames, did not receive a fabric login (FLOGI) frame,
and cannot join an operational fabric.
Director 2/64 Installation Guide