Resilience is a foundational attribute of Brocade Fibre Channel storage networks and resilience is also a requirement in modern data centers with clustered applications and demanding compute Service-Level Agreements (SLAs). In developing its VCS Fabric technology, Brocade naturally carried over this core characteristic to its Ethernet fabric design.
In traditional Ethernet networks running Spanning Tree Protocol (STP), only 50 percent of the links are active; the rest (shown as dotted lines in the previous figure) act as backups in case the primary connection fails.
When you connect two or more Brocade VCS Fabric mode-enabled switches they form an Ethernet fabric (provided the two switches have a unique RBridge ID and same VCS ID), as shown in the following figure.
The Ethernet fabric has the following characteristics:
- It is a switched network. The Ethernet fabric utilizes an emerging standard called Transparent Interconnection of Lots of Links (TRILL) as the underlying technology.
- All switches automatically know about each other and all connected physical and logical devices.
- All paths in the fabric are available. Traffic is always distributed across equal-cost paths. As illustrated in the figure, traffic from the source to the destination can travel across two paths.
- Traffic travels across the shortest path.
- If a single link fails, traffic is automatically rerouted to other available paths. In the topology shown in the figure, if one of the links in Active Path #1 goes down, traffic is seamlessly rerouted across Active Path #2.
- STP is not necessary because the Ethernet fabric appears as a single logical switch to connected servers, devices, and the rest of the network.
- Traffic can be switched from one Ethernet fabric path to the other Ethernet fabric path.