Online Training - 7

The network configuration for the vSphere infrastructure is a two-step process, whereby users must configure the physical network switches to which the vSphere host is connected and then configure the VDS. There are key network parameters, such as VLAN, network adapter teaming, and MTU, that should be configured properly on physical and virtual switches. 

However, there are occasions when there are network connectivity issues in the user environment because these parameters are not configured properly. Network connectivity issues caused by configuration errors are often difficult to identify. This particularly is the case in an organization where the network administrators and vSphere administrators take management ownership of physical network switches and vSphere hosts respectively. In earlier versions of vSphere, there were no tools available that could help resolve such misconfigurations across the physical and virtual switches.

Source: http://kb.vmware.com/kb/2032878

vSphere 5.1 and later allows you to rollback to previous networking configurations if a networking misconfiguration occurs. vSphere 5.1 also allows you to recover from any misconfiguration by connecting directly to a host to fix any networking issues through the Direct Console User Interface (DCUI). Rollback is available for use on both standard and distributed switches.

The management network is configured on every host and is used to communicate with vCenter Server and to interact with other hosts during vSphere HA configuration and operation. It is critical to centrally managing hosts through vCenter Server. If the management network on the host goes down or there is a misconfiguration, vCenter Server cannot connect to the host and therefore cannot centrally manage the vSphere infrastructure.In a vSphere standard switch (VSS) environment, you can recover from management network failure on the host by reconfiguring the host management network through a DCUI.

However, in the VDS environment, where multiple hosts are connected to a distributed switch, any network failure or misconfiguration of the management port group can potentially disconnect all hosts from the vCenter Server system. In this situation, vCenter Server cannot centrally make any changes to the VDS port group configuration and push those changes to hosts. The only way to recover from this situation is by going to individual hosts and building a VSS with a proper management network configuration. After all the hosts’ management networks have been reconfigured with a VSS and are able to communicate on the management network, vCenter Server can again manage the hosts and reconfigure the VDS.

To avoid such operational issues of going back to a VSS, if you do not have physical network interface card limitations on the hosts, you can make use of a VSS for the management network and a VDS for all other virtual infrastructure and virtual machine traffic. In such deployments, you must have at least four network adapters on the hosts: two connected to the VSS and two to the VDS.

The automatic rollback and recovery feature introduced in vSphere 5.1 addresses concerns regarding use of the management network on a VDS. First, the automatic rollback feature automatically detects any configuration changes on the management network. If the host cannot reach the vCenter Server system, it does not allow the changes to take effect. Second, you also have an option to reconfigure the management network of the VDS per host through the DCUI.

Source KB:  2032908

See also: Video - VMware vSphere 5.1 - Network Config Backup and Restore

A fundamental part of protecting IT is ensuring that the services provided by virtual machines are resilient, and  robust at all levels of the compute stack, from hardware through to the application. vSphere Replication is a feature introduced with VMware vSphere 5.1. It is designed to augment  the recovery capabilities of the VMware vSphere platform by providing a built-in capability to continually replicate a running virtual machine to another location.

Replication creates a copy of a virtual machine that can be stored locally within a cluster or at another site, providing a data source to rapidly restore a virtual machine within minutes. vSphere Replication augments offerings in the vSphere availability protection matrix. It provides a solution that enables recovery time better than that of restoring from backup, without introducing the complexity of a complete storage array–based replication configuration.

vSphere Replication also enables configuring replication on a per–virtual machine basis and significantly rounds out the capabilities of protection offered by vSphere. This paper will help you understand what vSphere Replication is and some of the benefits of its features. It will also discuss how it works to protect your virtual machines against failure.

Technical White Paper - Introduction to VMware vSphere Replication.pdf




See also: Video - VMware vSphere 5.1 - Replication Protection