This chapter describes how to configure the FabricPath interfaces on the Cisco Nexus 7000 Series NX-OS devices.
This chapter includes the following sections:
•Information About FabricPath Interfaces
•Licensing Requirements for FabricPath Interfaces
•Configuring FabricPath Interfaces
Information About FabricPath Interfaces
This section includes the following sections:
•STP and the FabricPath Network
Note You must have an F Series module installed in the Cisco Nexus 7000 Series device to run FabricPath.
After you enable FabricPath on the devices that you are using, you can configure an Ethernet interface or a port-channel interface as a FabricPath interface. If one member of the port channel is in FabricPath mode, all the other members will be in FabricPath mode. After you configure the interface as a FabricPath interface, it automatically becomes a trunk port, capable of carrying traffic for multiple VLANs. You can also configure all the ports on the F Series module as FabricPath interfaces simultaneously.
The following interface modes carry traffic for the following types of VLANs:
•Interfaces on the F Series modules that are configured as FabricPath interfaces can carry traffic:
–ONLY for FP VLANs.
•Interfaces on the F Series modules that are not configured as FabricPath interfaces carry traffic for the following:
–Classical Ethernet (CE) VLANS
•Interfaces on the M Series modules carry traffic:
–ONLY for CE VLANs
Note See Chapter 5 "FabricPath Forwarding" for information about FP and CE VLANs.
The FabricPath interfaces connect only to other FabricPath interfaces within the FabricPath network. These FabricPath ports operate on the information in the FabricPath headers and Layer 2 Intermediate System-to-Intermediate System (IS-IS) only, and they do not run STP. These ports are aware only of FP VLANs; they are unaware of any CE VLANs. By default, all VLANs are allowed on a trunk port, so the FabricPath interface carries traffic for all FP VLANs.
Note You cannot configure FabricPath interfaces as shared interfaces. See Cisco NX-OS FCoE Configuration Guide for Cisco Nexus 7000 and Cisco MDS 9500 for information on shared interfaces.
STP and the FabricPath Network
Note The Layer 2 gateway switches, which are on the edge between the CE and the FabricPath network, must be the root for all STP domains that are connected to an FabricPath network.
The Spanning Tree Protocol (STP) domains do not cross into the FabricPath network (see Figure 4-1).
Figure 4-1 STP Boundary Termination at FabricPath Network Border
You must configure the FabricPath Layer 2 gateway device to have the lowest STP priority of all the devices in the STP domain to which it is attached. You must also configure all the FabricPath Layer 2 gateway devices connected to one FabricPath network to have the same priority. The system assigns the bridge ID for the Layer 2 gateway devices from a pool of reserved MAC addresses.
To have a loop-free topology for the CE/FabricPath hybrid network, the FabricPath network automatically presents a s a single bridge to all connected CE devices.
Note You must set the STP priority on all FabricPath Layer 2 gateway switches to a value low enough to ensure that they become root for any attached STP domains.
Other than configuring the STP priority on the FabricPath Layer 2 gateway switches, you do not need to configure anything for the STP to work seamlessly with the FabricPath network. Only connected CE devices form a single STP domain. Those CE devices that are not interconnected form separate STP domains (see Figure 4-1).
All CE interfaces should be designated ports, which occurs automatically, or they will be pruned from the active STP topology. If the system does prune any port, the system returns a syslog message. The system clears the port again only when that port is no longer receiving superior BPDUs.
The FabricPath Layer 2 gateway switch also propagates the Topology Change Notifications (TCNs) on all its CE interfaces.
The FabricPath Layer 2 gateway switches terminate STP. The set of FabricPath Layer 2 gateway switches that are connected by STP forms the STP domain. Because there can be many FabricPath Layer 2 gateway switches attached to a single FabricPath network, there may also be many separate STP domains (see Figure 4-1). The devices in the separate STP domains need to know TCN information only for the domain to which they belong. You can configure a unique STP domain ID for each separate STP domain that connects to the same FabricPath network. The Layer 2 IS-IS messages will carry the TCNs across the FabricPath network. Only those FabricPath Layer 2 gateway switches in the same STP domain as the TCN message need to act and propagate the message to connected CE devices.
When a FabricPath Layer 2 gateway switch receives a TCN for the STP domain it is part of, it takes the following actions:
•Flushes all remote MAC addresses for that STP domain and the MAC addresses on the designated port.
•Propagates the TCN to the other devices in the specified STP domain.
The devices in the separate STP domains need to receive the TCN information and then take the following action:
•Flush all remote MAC addresses reachable by the STP domain that generated the TCN information.
The FabricPath topologies retain their configuration through ISSU.
See the Cisco Nexus 7000 Series NX-OS High Availability and Redundancy Guide, Release 5.x, for more information on high availability.
Licensing Requirements for FabricPath Interfaces
The following table shows the licensing requirements for this feature:
FabricPath requires an Enhanced Layer 2 license. For a complete explanation of the Cisco NX-OS licensing scheme, see the Cisco Nexus 7000 Series Licensing Guide.
FabricPath requires no license. Any feature not included in a license package is bundled with the Cisco DCNM and is provided at no charge to you. For an explanation of the Cisco DCNM licensing scheme, see the Cisco DCNM Installation and Licensing Guide.
The following platform supports this feature. For platform-specific information, including guidelines and limitations, system defaults, and configuration limits, see the corresponding documentation.
Configuring FabricPath Interfaces
See the Interfaces Configuration Guide, Cisco DCNM for LAN, Release 5.x for information on configuring FabricPath interfaces using DCNM.
See the Layer 2 Switching Configuration Guide, Cisco DCNM for LAN, Release 5.x for information on configuring STP.
Feature History for Configuring FabricPath Using the DCNM
Table 4-1 lists the release history for this feature.
Table 4-1 Feature History for FabricPath Switching
These features were introduced.