designated master port. If a port or a switching module fails, the PortChannel continues to function properly
without requiring fabric reconfiguration.
Cisco NX-OS software uses a protocol to exchange PortChannel configuration information between adjacent
switches to simplify PortChannel management, including misconfiguration detection and autocreation of
PortChannels among compatible ISLs. In the autoconfigure mode, ISLs with compatible parameters
automatically form channel groups; no manual intervention is required.
PortChannels load balance Fibre Channel traffic using a hash of source FC-ID and destination FC-ID, and
optionally the exchange ID. Load balancing using PortChannels is performed over both Fibre Channel and
FCIP links. Cisco NX-OS software also can be configured to load balance across multiple same-cost FSPF
routes.
Virtual SANs
Virtual SANs (VSANs) partition a single physical SAN into multiple VSANs. VSANs allow the Cisco NX-OS
software to logically divide a large physical fabric into separate, isolated environments to improve Fibre
Channel SAN scalability, availability, manageability, and network security.
Each VSAN is a logically and functionally separate SAN with its own set of Fibre Channel fabric services.
This partitioning of fabric services greatly reduces network instability by containing fabric reconfiguration
and error conditions within an individual VSAN. The strict traffic segregation provided by VSANs can ensure
that the control and data traffic of a specified VSAN are confined within the VSAN's own domain, which
increases SAN security. VSANs can reduce costs by facilitating consolidation of isolated SAN islands into a
common infrastructure without compromising availability.
You can create administrator roles that are limited in scope to certain VSANs. For example, you can set up a
network administrator role to allow configuration of all platform-specific capabilities and other roles to allow
configuration and management only within specific VSANs. This approach improves the manageability of
large SANs and reduces disruptions due to human error by isolating the effect of a user action to a specific
VSAN whose membership can be assigned based on switch ports or the worldwide name (WWN) of attached
devices.
VSANs are supported across Fibre Channel over IP (FCIP) links between SANs, which extends VSANs to
include devices at a remote location. The Cisco SAN switches also implement trunking for VSANs. Trunking
allows Inter-Switch Links (ISLs) to carry traffic for multiple VSANs on the same physical link.
Zoning
Zoning provides access control for devices within a SAN. The Cisco NX-OS software supports the following
types of zoning:
•
N port zoning-Defines zone members based on the end-device (host and storage) port.
◦
WWN
◦
Fibre Channel identifier (FC-ID)
•
Fx port zoning-Defines zone members based on the switch port.
◦
WWN
◦
WWN plus the interface index, or domain ID plus the interface index
•
Domain ID and port number (for Brocade interoperability)
•
iSCSI zoning-Defines zone members based on the host zone.
◦
iSCSI name
Cisco Nexus 5500 Series NX-OS SAN Switching Configuration Guide, Release 7.x
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OL-30895-01
Overview
SAN Switching Overview
