Forwarding Model - Cisco Nexus 2000 Series Manual

Overview

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 1: Forwarding Model
The forwarding model facilitates feature consistency between the Fabric Extender and its parent Cisco Nexus
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 that are sent
from the parent switch for multicast addresses attached to the Fabric Extender are replicated by the Fabric
Extender ASICs and are then sent to corresponding hosts.
Cisco Nexus 2000 Series NX-OS Fabric Extender Software Configuration Guide for Cisco Nexus 7000 Series
Forwarding Model
Switches, Release 5.2
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