Much awaited LACP enhancement – vSphere 5.5

In vSphere 5.1, LACP implementation has some constraints and those were:

  • Supports only one LAG per VDS per host.
  • All uplinks in the dvuplink port group are included in this LAG.
  • Only the IP hash load balancing algorithm is supported.


So essentially what we were missing are:

  • Multiple LAGs per host.
  • Multiple load balancing options.


Before I move onto how vSphere 5.5 has resolved these constraints, let me reiterate few basics about LACP.


LACP – Link Aggregation Control Protocol is a standards-based method (IEEE 802.3ad) to control the bundling of physical network links to form a logical channel for increased bandwidth and redundancy purposes.


LAG – A Link Aggregation Group is a grouping of multiple individual links – with compatible properties – formed into a single logical channel. This can be a manual process or performed by a controlling protocol such as LACP.


Hashing Algorithm – The hashing algorithm determines the LAG member used for traffic. LACP can use different properties of the outgoing traffic (e.g. source IP/Port number) to distribute traffic across all the links participating in a LAG.


LACP is installed as a kernel module and user world daemon lacp_uw. The module will be automatically loaded and the daemon executed after the host boots.


Now let me show you a typical setup to make you understand what is the enhancement VMware has made in version 5.5




But Why do you need multiple LAG?

  • DC networks moving towards 10GbE, which require multiple etherchannels
  • Hosts with mix of 1GbE and 10GbE NICs need multiple etherchannel support


Enhancement In vSphere 5.5

  • Support multiple LACP LAGs
  • Max 32 LAG per Host
  • Max 64 LAG per VDS
  • Support all supported hashing algorithms in LACP (22)


LAGs are composed of new LAG uplinks. Each physical NIC (vmnic) taking part in the LAG is assigned to a single LAG uplink.


Note: Uplinks must be going to either the same switch or a pair of switches appearing as a single logical switch (using vPC, VSS, MLAG, SMLT, or similar technology).


About Prasenjit Sarkar

Prasenjit Sarkar is a Product Manager at Oracle for their Public Cloud with primary focus on Cloud Strategy, Cloud Native Applications and API Platform. His primary focus is driving Oracle’s Cloud Computing business with commercial and public sector customers; helping to shape and deliver on a strategy to build broad use of Oracle’s Infrastructure as a Service (IaaS) offerings such as Compute, Storage, Network & Database as a Service. He is also responsible for developing public/private cloud integration strategies, customer’s Cloud Computing architecture vision, future state architectures, and implementable architecture roadmaps in the context of the public, private, and hybrid cloud computing solutions Oracle can offer.

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