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Networks have always been a pain point for enterprise data centers; configurations often required manual intervention,...
were cumbersome to implement and almost impossible to maintain or change over time.
Now that virtualization has moved beyond virtual machines to embrace the underlying network, administrators can employ tools like vSphere Standard Switch to provide programmatic control over network organization and performance for each ESXi host. The move to vSphere Distributed Switch adds powerful network features and aggregates all of the per-host virtual switches as a single distributed switch at the data center level through platforms like vCenter Server. Let's take a closer look at vSphere Distributed Switch and what it brings to the enterprise.
What are vSphere Distributed Switches and what advantages could they bring to the data center?
A vSphere Distributed Switch (vDS) is a logical aggregation of vSphere Standard Switch (vSS) deployments within a data center environment.
Normally, each ESXi -- vSphere -- host would employ a vSS to move traffic from VMs to the underlying physical switches and out to the network. A vSS provides software-based features and control including L2 frame forwarding, network interface card teaming for increased bandwidth and redundancy, outbound traffic shaping for better VM traffic performance, virtual LAN (VLAN) segmentation support with 802.1Q encapsulation and support for Cisco Discovery Protocol, which allows discovery of Cisco equipment on the network. This allows for the creation of detailed, complex logical network topologies within the enterprise network.
The issue with vSS instances is that they exist on each ESXi host, requiring administrators to create, configure and maintain each vSS on an individual basis -- there is always a possibility of inconsistent or overlooked configuration options leading to performance penalties or security vulnerabilities.
A vSphere Distributed Switch provides a software-based mechanism to aggregate and organize vSS host instances under a single umbrella managed by vCenter Server. With a vSphere Distributed Switch, up to 500 ESXi hosts within the same host cluster can use the same distributed switch. VDS logically represents all of the vSS instances as a single switch, and vDS configuration choices are pushed to the underlying vSS instances to prevent errors or oversights and ensure consistent management of the virtual switch environment.
A vDS is comprised of two logical levels: a control plane and an I/O plane. The control plane is provided through vCenter Server, which configures and manages the vDS along with advanced features like distributed port groups -- defining how connections are made to the network, uplinks, NIC teaming, private VLANs and more. The I/O plane is an element installed on each ESXi host that manages the network hardware and forwards traffic to the correct links. This approach ensures that traffic will continue even if vCenter Server fails.
In addition to enterprise-level management, vSphere Distributed Switches adds a suite of other features including private VLANs, link aggregation control and port mirroring to boost NIC teaming, port state monitoring, inbound traffic shaping for better network performance, traffic filtering, network I/O control, NetFlow for traffic analysis, and even vDS configuration backup and restoration.
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