The Cisco Application
Virtual Switch (AVS) is a key part of the Cisco Application Centric
Infrastructure (ACI). It is a distributed virtual switch that offers different
forwarding and encapsulation options and extends across many virtualized hosts
and data centers defined by the VMware vCenter Server.
The Cisco AVS is
integrated with the Cisco ACI architecture as a virtual leaf and is managed by
the Cisco APIC. The
implements the OpFlex protocol for control plane communication.
This section provides
an overview of the Cisco AVS.
supports two modes of traffic forwarding: Local Switching mode, formerly known
as Fex disable mode; and No Local Switching mode, formerly known as Fex enable
mode. You choose the forwarding mode during
In Local Switching mode, all intra-EPG traffic is locally forwarded by the Cisco AVS, without the involvement of the leaf. All inter-EPG traffic is forwarded through the leaf. In this mode, the Cisco AVS can use either VLAN or VXLAN encapsulation—or both—for forwarding traffic to the leaf and back. You choose the encapsulation type during Cisco AVS installation.
Beginning with Cisco AVS Release 5.2(1)SV3(2.5), you can configure a single VMM domain in Local Switching mode to use VLAN and VXLAN encapsulation. Previously, encapsulation was determined solely by the presence of VLAN or multicast pools, and you needed to have separate VMM domains for EPGs using VLAN and VXLAN encapsulation.
If you choose VLAN
encapsulation, a range of VLANs must be available for use by the
These VLANs have local scope in that they have significance only within the
Layer 2 network between the
and the leaf. If you choose VXLAN encapsulation, only the infra-VLAN needs to
be available between the
and the leaf. This results in a simplified configuration and is the recommended
encapsulation type if there are one or more switches between the
and the physical leaf.
Figure 3. The
in Local Switching Mode
In No Local
Switching mode, all traffic is forwarded by the leaf. In this mode, VXLAN is
the only allowed encapsulation type.
Figure 4. The
in No Local Switching Mode