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VCAP-DCA Study notes – 2.1 Implement and Manage Complex Virtual Networks

The VCAP-DCA lab is still v4.0 (rather than v4.1) which means features such as NIOC and load based teaming (LBT) aren’t covered. Even though the Nexus 1000V isn’t on the Network objectives blueprint (just the vDS) it’s worth knowing what extra features it offers as some goals might require you to know when to use the Nexus1000V or just the vDS.


  • Identify common virtual switch configurations

Skills and Abilities

  • Determine use cases for and apply IPv6
  • Configure NetQueue
  • Configure SNMP
  • Determine use cases for and apply VMware DirectPath I/O
  • Migrate a vSS network to a Hybrid or Full vDS solution
  • Configure vSS and vDS settings using command line tools
  • Analyze command line output to identify vSS and vDS configuration details

Tools & learning resources

Network basics (VCP revision)

Standard switches support the following features (see section 2.3 for more details);

  • NIC teaming
    • Based on source VM ID (default)
    • Based on IP Hash (used with Etherchannel)
    • Based on source MAC hash
    • Explicit failover order

vDS Revision

The vDistributed switch separates the control plane and the data place to enable centralised administration as well as extra functionality compared to standard vSwitches. A good summary can be found at GeekSilver’s blog. Benefits;

  • Offers both inbound and outbound traffic shaping (standard switches only offer outbound)
    • Traffic shaping can be applied at both dvPortGroup and dvUplink PortGroup level
    • For dvUplink PortGroups ingress is traffic from external network coming into vDS, egress is traffic from vDS to external network
    • For dvPortGroups ingress is traffic from VM coming into vDS, egress is traffic from vDS to VMs
    • Configured via three policies – average bandwidth, burst rate, and peak bandwidth
  • Ability to build a third party vDS on top (Cisco Nexus 1000v)
  • Traffic statistics are available (unlike standard vSwitches)



  • CDP and MTU are set per vDS (as they are with standard vSwitches).
  • PVLANs are defined at switch level and applied at dvPortGroup level.
  • There is one DVUplink Portgroup per vDS
  • NIC teaming is configured at the dvPortGroup level but can be overridden at the dvPort  level (by default this is disabled but it can be allowed). This applies to both dvUplink Portgroups and standard dvPortGroups although on an uplink you CANNOT override the NIC teaming or Security policies.
  • Policy inheritance (lower level takes precedence but override is disabled by default)
    • dvPortGroup -> dvPort
    • dvUplink PortGroup -> dvUplinkPort

NOTE: Don’t create a vDS with special characters in the name (I used ‘Lab & Management’) as it breaks host profiles – see VMwareKB1034327.

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