Dynamic Workload Scaling

Dynamic Workload Scaling ( DWS )



Dynamic Workload Scaling ( DWS ) 

Dynamic workload scaling is all about monitoring and distributing traffic at user-defined thresholds. Data centers are under pressure to support the ability to burst new transactions to available Virtual Machines ( VM ). In some cases, the VMs used to handle the additional load will be geographically dispersed, with both data centers connected by a Data Center Interconnect ( DCI ) link. The ability to migrate workloads within an enterprise hybrid cloud or in a hybrid cloud solution between enterprise and service provider is critical for business continuity for planned and unplanned outages.


Preliminary Information: Useful Links to Relevant Content

Before you proceed, you may find the following post helpful:

  1. Network Security Components
  2. Virtual Data Center Design
  3. How To Scale Load Balancer
  4. Distributed Systems Observability
  5. Active Active Data Center Design
  6. Cisco Secure Firewall


Dynamic Workloads

Key Dynamic Workload Scaling Discussion Points:

  • Introduction to Dynamic Workload Scaling and what is involved.

  • Highlighting the details of dynamic workloads and how they can be implemented.

  • Critical points on how Cisco approaches Dynamic Workload Scaling.

  • A final note on design considerations.


A Key Point: Knowledge Check 

  • A key point: Back to basics with OTV.

Overlay Transport Virtualization (OTV) is an IP-based technology to provide a Layer 2 extension between data centers. OTV is transport agnostic, indicating that the transport infrastructure between data centers can be dark fiber, MPLS, IP routed WAN, ATM, Frame Relay, etc. The sole prerequisite is that the data centers must have IP reachability between them. OTV permits multipoint services for Layer 2 extension and separated Layer 2 domains between data centers, maintaining an IP-based interconnection’s fault-isolation, resiliency, and load-balancing benefits.

Unlike traditional Layer 2 extension technologies, OTV introduces the Layer 2 MAC routing concept. The MAC-routing concept enables a control-plane protocol to advertise the reachability of Layer 2 MAC addresses. As a result, the MAC-routing idea has enormous advantages over traditional Layer 2 extension technologies that traditionally leveraged data plane learning, flooding Layer 2 traffic across the transport infrastructure.


Cisco and Dynamic Workloads

A new technology introduced by Cisco, called Dynamic Workload Scaling ( DWS ), satisfies the requirement of dynamically bursting workloads based on user-defined thresholds to available resource pools ( VMs ). It is tightly integrated with Cisco Application Control Engine ( ACE ) and Cisco’s Dynamic MAC-in-IP encapsulation technology known as Overlay Transport Virtualization ( OTV ), enabling resource distribution across Data Center sites. OTV provides the LAN extension method that keeps the virtual machine’s state as it passes locations, and ACE delivers the load-balancing functionality.


dynamic workloads
Dynamic workload and dynamic workload scaling.


Dynamic workload scaling: How does it work?  

  • DWS monitors the VM capacity for an application and expands that application to another resource pool during periods of peak usage. We provide a perfect solution for distributed applications among geographically dispersed data centers.
  • DWS uses the ACE and OTV technologies to build a MAC table. It monitors the local MAC entries and those located via the OTV link to determine if a MAC entry is considered “Local” or “Remote.”
  • The ACE monitors the utilization of the “local” VM. From these values, the ACE can compute the average load of the local Data Center.
  • DWS uses two APIs. One is to monitor the server load information polled from VMware’s VCenter, and another API is to poll OTV information from the Nexus 7000.
  • During normal load conditions, when the data center is experiencing low utilization, the ACE can load incoming balance traffic to the local VMs.
  • However, when the data center experiences high utilization and crosses the predefined thresholds, the ACE will add the “remote” VM to its load-balancing mechanism.
workload scaling
Workload scaling and its operations.


Dynamic workload scaling: Design considerations

During congestion, the ACE adds the “remote” VM to its load-balancing algorithm. The remote VM placed in the secondary data center could add additional load on the DCI. Essentially hair-pining traffic for some time as ingress traffic for the “remote” VM continues to flow via the primary data center. DWS should be used with Locator Identity Separation Protocol ( LISP ) to enable automatic move detection and optimal ingress path selection.


Matt Conran
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