SDWAN Considerations

This article refers to the design and implementation of a Software Defined Wide Area Network (SDWAN) in a global organisation with ~350 circuits, 90 locations (NA, EMEA & APAC) including sales offices, call centres, regional HQ buildings, data centres and cloud providers.

What is Software Defined Networking?

Software Defined Networking, or SDN, is a way of programmatically directing data traffic across multiple paths to improve speed, efficiency, quality of service, monitoring and cost. SDWAN refers to a software defined Wide Area Network.

Why should I consider SDWAN?

#1 - Cost Reductions from SDWAN

SD WAN is generally considered when organisations want to reduce their WAN costs by replacing or reducing high-cost MPLS bandwidth with multiple low-cost internet circuits.

Compared to internet circuits, the equivalent MPLS bandwidth can cost 2x to 9x depending upon location so moving traffic to the internet and reducing or replacing MPLS bandwidth can yield high savings.

#2 - SDWAN Centralised Management

Networking policies are centralised, and global configuration changed can be pushed out and applied at a global level. This advantage is offset by an obvious disadvantage – see “SDWAN Operations Considerations".

#3 - Application Quality of Service with SDWAN

Quality of service at the application level allows redirecting the traffic (not just queueing) across the circuit that will provide the best SLA for that application. Applications with lower SLA/QoS requirements can therefore be passed across lower quality or cheaper circuits while high value traffic can be set to favour quicker more reliable, more expensive circuits if the lower cost circuits do not provide that SLA.

SDWAN Architecture

The SDWAN Architecture can be seen to be split in two

  • A command and control centre (the control plane) and

  • A routing function (data plane) that carries out the rules handed down from the control plane

Splitting the control plane in this way is what allows for centralised management and the commoditisation of the edge devices.

Owned and operated SDWAN

The basic SDWAN solution provides the hardware and embedded software to allow customers to connect and aggregate their existing circuits. Existing firewalls, intrusion protection, WAN accelerators and caches etc need to be integrated into the design

This arrangement best suits organisations that want to maintain control and management of their network.

Managed SDWAN

A managed service SDWAN may provide the (relatively dumb) edge hardware and connect each location to the vendor’s local SDWAN POP. The intelligent routing and control functions are then hosted by the vendor in their cloud on behalf of the customer.

The managed service vendor will usually offer additional value-added services such as firewall management, NOC and handles all the routine management activities that keep a network patched and operating to the contracted SLA.

What to Consider When Deploying SDWAN

SDWAN Design considerations:

  • Circuit sizing MPLS vs Internet and rules for future optimisation

  • Application QoS/SLA settings

  • Integration with legacy firewalls and WAN accelerators

  • Audit of site standards

  • Hybrid configurations and traffic routing when some sites are on SD WAN and others on legacy WAN

  • Integration with corporate data centres and ecommerce applications

  • Security team policies

Deployment Considerations for SDWAN:

  • Implementation costs and timescales

  • Simplicity of installation at remote sites

  • Roll-back scenarios

  • QA and commissioning routines

  • Global logistics

  • Out of hours support channels

SDWAN Operations considerations:

  • Training

  • Escalation paths

  • Lab environments that replicate ‘real-life’

  • Change management processes

  • Managing rolling code updates for immature and evolving products

Telecoms Expense Management and SDWAN:

  • Auditing all circuit contracts for cost and term

  • Base-lining existing WAN costs to demonstrate savings at macro and micro level

  • Modelling the future costs based on the optimisation rules

  • Simplifying the quote/order/install process

About Karumba Consulting

Karumba Consulting provides project management and technical execution capability on transformation projects for large organisations. Karumba can help articulate the business case and drive the internal teams and external vendors to realise that business case with agility, speed and control.

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