Configuring brocade vcs fabrics, Fabric overview, Brocade vcs fabric formation – Brocade Network OS Administrator’s Guide v4.1.1 User Manual
Page 145: Configuring, Brocade vcs fabrics, Refer to
Configuring Brocade VCS Fabrics
Fabric overview
The Brocade VCS Fabric Ethernet fabric is defined as a group of switches that exchange information
between each other to implement distributed intelligence. The Brocade Ethernet fabric uses
Transparent Interconnection of Lots of Links (TRILL) protocol, designed for the sole purpose of scaling
Ethernet networks by allowing a set of devices, called routing bridges (RBridges), to connect with each
other.
A link state dynamic routing protocol, rather than Spanning Tree Protocol, determines how the traffic is
forwarded between the inter-connected RBridges. Link state routing in Brocade VCS Fabric-based
TRILL networks is performed using Fabric Shortest Path First (FSPF) protocol.
TRILL enables Layer 2 networks to behave like routed Layer 3/IP networks. TRILL also defines native
support for forwarding both unicast and multicast traffic, and therefore unifies support for both of these
different classes of applications over a single transport.
Brocade VCS Fabric formation
Brocade VCS Fabric technology uses RBridge identifiers (IDs) to discover fabric creation problems,
such as duplicate IDs. The RBridge ID of a cluster unit is equal to the domain ID of an FC switch.
RBridge ID assignment is implemented by leveraging the domain ID assignment protocols in the FC
SANs. Request for Domain ID (RDI) and Domain ID Assignment (DIA) protocols ensure that a single
switch (the principal switch) is centrally allocating the domain IDs for every RBridge in the fabric and
detecting any domain ID conflicts in the fabric. In case of conflict, the conflicting node is segmented
from the fabric. You must take action to resolve the conflict
NOTE
Fabrics based on Network OS 4.0.0 and later can have a maximum of 239 RBridges in a single
Brocade VCS Fabric. However, Brocade recommends using only 24 RBridges per fabric.
The following sequence of events describes the Brocade VCS Fabric formation process:
• Each Brocade VCS Fabric is identified by a VCS ID.
• All Brocade VCS Fabric-capable switches are configured with a factory default VCS ID of 1.
• The switch software searches for the "VCS enable" attribute.
NOTE
If the software cannot locate the "VCS enable" attribute, the switch goes into standalone mode and
operates like a regular 802.1x switch.
• Assuming the switch is Brocade VCS Fabric-enabled, the switch software invokes a series of
protocols:
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