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Figure 1.
Cisco Nexus Virtual Chassis Topology
The Cisco Nexus 5000 Series Switches, along with the Cisco Nexus 2000 Series and Cisco Nexus B22, create a
distributed modular system that unifies the data center architecture. Within this distributed modular system, both
blade servers and rack servers are managed identically. This approach allows the use of the same business and
technical processes and procedures for the network when addressing the computing environment.
The left most blade chassis in Figure 1 contains dual Cisco Nexus B22HP fabric extenders. Each Cisco Nexus
B22HP is singly attached to a parent Cisco Nexus 5500 switch platform, a connection mode referred to as straight
through mode. The fabric links can either be statically pinned or put into a PortChannel. This connection mode
helps ensure that all data packets from a particular Cisco Nexus B22 enter the same parent Cisco Nexus 5500
switch platform. This approach may be necessary when certain types of traffic must be restricted to either the left
or right Cisco Nexus 5500 switch platform: for instance, to maintain SAN A and SAN B separation. Also, in this
example the connections to individual blade servers are in active-standby mode, which helps ensure traffic flow
consistency but does not fully utilize the server network interface card (NIC) bandwidth.
The second blade chassis from the left in Figure 1 improves on the first with the creation of an Ethernet virtual
PortChannel (vPC) from the blade servers to the Cisco Nexus 5500. This vPC places the Ethernet portion of the
NICs in an active-active configuration, giving increased bandwidth to each host. The FCoE portion of the CNA is
also configured as active-active but maintains SAN A and SAN B separation because each virtual Fibre Channel
(VFC) interface is bound to a particular link at the server. This configuration also achieves high availability through
redundancy, and it can withstand a failure of a Cisco Nexus 5500 switch platform, a Cisco Nexus B22HP, or any
connecting cable. This topology is widely used in FCoE deployments.
