The Importance of Directly Connecting Converged Network Adapters

Explanation.

When directly connecting converged network adapters (CNAs) to the fabric, there are several best practices that should be followed to ensure optimal performance and stability of the network. The three best practices are as follows:

A. Cisco Unified Fabric links must be configured as access ports and FCoE VLAN must not be configured as a native VLAN.

In a converged network, Ethernet and Fibre Channel traffic share the same physical network infrastructure. To separate these types of traffic, a special VLAN called FCoE VLAN is used. When configuring the Cisco Unified Fabric links, they should be set up as access ports rather than trunk ports to ensure that only one VLAN (the FCoE VLAN) is allowed on the link. Additionally, the FCoE VLAN must not be configured as a native VLAN, as this can lead to unwanted traffic on the network.

B. Separate FCoE VLANs must be used for FCoE in SAN-A and SAN-B.

It is recommended to use separate FCoE VLANs for FCoE traffic in different SAN fabrics (SAN-A and SAN-B). This ensures that the traffic is isolated and avoids any potential conflicts that could arise from using the same FCoE VLAN in multiple fabrics.

C. If MSTP is enabled, a separate MST instance must be used for FCoE VLANs.

Multiple Spanning Tree Protocol (MSTP) is used to prevent loops in a network with multiple VLANs. If MSTP is enabled, a separate MST instance must be used for FCoE VLANs to ensure that they are not affected by changes to other VLANs. This ensures that the FCoE traffic is stable and reliable.

D. If the converged access switches (in the same San fabric or in the other) must be connected to each over Ethernet links for the purposes of LAN alternate pathing, then such links must explicitly be configured to include all FCoE VLANs. This configuration ensures to extend the scope of the Spanning Tree Protocol for FCoE VLANs to Cisco Unified Fabric and non Cisco Unified Fabric links.

In a network with multiple switches, alternate pathing is used to provide redundancy and avoid single points of failure. If converged access switches are connected to each other via Ethernet links for alternate pathing, these links must be explicitly configured to include all FCoE VLANs. This ensures that the Spanning Tree Protocol is extended to cover FCoE VLANs on both Cisco Unified Fabric and non- Cisco Unified Fabric links.

E. Cisco Unified Fabric links must be configured as spanning-tree edge ports.

To improve network convergence time and avoid unnecessary traffic, Cisco Unified Fabric links should be configured as Spanning Tree Protocol (STP) edge ports. This ensures that the ports are in the forwarding state immediately when they come up, reducing the time it takes for traffic to flow through the network.

F. A shared VLAN can be used to carry traffic for each virtual fabric in the SAN (for example, VSAN 1, VSAN 2, and so on).

A shared VLAN can be used to carry traffic for each virtual fabric in the SAN. This simplifies the network design and reduces the number of VLANs required, making it easier to manage the network.

In conclusion, when directly connecting converged network adapters to the fabric, best practices include configuring Cisco Unified Fabric links as access ports, using separate FCoE VLANs for different SAN fabrics, using separate MST instances for FCoE VLANs, explicitly configuring alternate pathing links to include all FCoE VLANs, configuring Cisco Unified Fabric links as STP edge ports, and using a shared VLAN to carry traffic for each virtual fabric in the SAN.