Forwarding Model; Connection Model - Cisco Nexus 5000 Series Configuration Manual

Configuring the Fabric Extender

Forwarding Model

The Cisco Nexus 2000 Series Fabric Extender does not perform any local switching. All traffic is sent to the
parent switch that provides central forwarding and policy enforcement, including host-to-host communications
between two systems that are connected to the same Fabric Extender as shown in the following figure.
Figure 30: Forwarding Model
The forwarding model facilitates feature consistency between the Fabric Extender and its parent Cisco Nexus
5000 Series device.
The Fabric Extender provides end-host connectivity into the network fabric. As a result, BPDU Guard is
Note
enabled on all its host interfaces. If you connect a bridge or switch to a host interface, that interface is
placed in an error-disabled state when a BPDU is received.
You cannot disable BPDU Guard on the host interfaces of the Fabric Extender.
The Fabric Extender supports egress multicast replication from the network to the host. Packets sent from the
parent switch for multicast addresses attached to the Fabric Extender are replicated by the Fabric Extender
ASICs and then sent to corresponding hosts.

Connection Model

Two methods (the static pinning fabric interface connection and the EtherChannel fabric interface connection)
allow the traffic from an end host to the parent switch to be distributed when going through the Cisco Nexus
2000 Series Fabric Extender.
Cisco Nexus 5000 Series NX-OS Layer 2 Switching Configuration Guide, Release 5.0(3)N1(1)

Forwarding Model

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