Simplified, High-Performance 10GbE Networks Based on a Single Virtual Distributed Switch, Managed by VMware* vSphere 5.1

Uplinks (to core switch)
Uplinks (to core switch)
Non-virtualized infrastructure:
Multiple servers are connedted to a top-of-rack physical switch
Virtualized server consolidation:
Each server is replaced by a VM, co-located on the virtualized
host and networked using a software-based virtual switch
APP
OS
VM
APP
OS
VM
APP
OS
VM
VMware vSphere* ESXi
VMware VSS
Physical
Host server
vNICs vNICs vNICs
Figure 1. VMware vSphere Standard Switches (VSSs) connect multiple
virtual machines (VMs) within the physical host, analogous to top-of-rack
switches connecting multiple servers within a rack.
to external networks through the use of physical Ethernet
network adapters. Moving the access layer from the physical- to
software-based virtual entities allows the environment to more
dynamically assign network resources as needed, addressing the
limitations listed above by creating a more agile network in the
presence of changing conditions.
In the virtualized server-consolidation scenario, the physical
host’s network connections function as switch uplinks that
carry trafc from a large number of VMs, in the same way that
on the left side, the top-of-rack switch’s uplinks carry trafc
from a large number of physical servers. Therefore, the network
connections on physical hosts should use the same type of
congurations used on switch uplinks, such as using 10GbE
connections, rather than the 1GbE connections used on the non-
virtualized servers. This transition is described in greater detail in
the Intel technology brief, “Virtual Switches Demand Rethinking
Connectivity for Servers.”
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A common approach in deploying new technologies is to use
existing data center deployment models to ease the transition as
new methods are developed and paradigm shifts in thinking are
accepted. In some cases, new methods or products are created to
help bridge the old models and new technologies. These bridging
methods tend to lose favor quickly as new deployment models
are proven and the earlier methods become regarded as more
restrictive than useful. An example of a bridging method is to
carve up a 10GbE port into multiple smaller ports that are
a subset of the total 10 Gb potential bandwidth.
This deployment method could have helped organizations
transition their multiple-port 1GbE hosts to 10GbE by not having
to change their previous VSS conguration tools used in older
version of VMware products. However, it limited the use of the
enhancements and optimizations of the VDS made available in
VMware vSphere 5.0. While the transition from 1GbE to 10GbE
requires upgrading the physical switch and network adapters
on the hosts, the transition from carved-up 10GbE ports to “big
open pipes” to the server is primarily a software conguration
change. In that sense, this transition is analogous to removing
trafc cones that were temporarily used to direct trafc during
road construction.
The recent advances in server performance and the convergence
of network and storage networking provide further enhancements
that benet this “big open pipe” model, in terms of exibility
and performance. In conjunction with those advances, the
QoS features in virtualization software such as vSphere and
related network management tools continue to drive more
sophisticated usage models, making it relatively straightforward
to accommodate multiple trafc types on a single virtual
switch while achieving line-rate throughput that rivals or even
outperforms the earlier physical server deployment models.
In the virtualized server-consolidation scenario shown in Figure 1,
a software-based virtual switch (such as the VMware VSS) is
used to route trafc among the VMs, acting analogously to
the top-of-rack switch in the non-virtualized case. In addition
to handling network trafc within the host, a VSS can connect
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Simplied, High-Performance 10GbE Networks Based on a Single Virtual Distributed Switch, Managed by VMware vSphere* 5.1
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