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SD WAN: Exploring the benefits

Deployment Benefits

SD WAN brings a number of benefits to the deployment of a WAN.  If you are a large enterprise managing your own WAN then you should see these benefits directly. If you have bought a Managed WAN then it is likely that your service provider will see them.  Nonetheless, it is to be hoped that you would enjoy a better service as a result.

SD WAN can reduce the time and therefore cost of deployment by using templates.

SD WAN allows you to design a template up front, and then have each site deployed using the template (with adjustments for IP Addresses).  Devices therefore don’t need to be physically staged, or at least require minimal staging.

With a traditional WAN templates can still be used but they are kept as text files, which can take longer to create and can be misused.

With a traditional WAN, different routers have different Command Line Interface (CLI) commands; making templates more difficult to create.  Also, there are many ways to achieve the same result, meaning a lack of consistency to configuration templates.

SD WAN can reduce the mistakes of deployment

We periodically hear from businesses who have experienced mistakes in network deployment. One of the drivers for these mistakes is the inconsistent production of router configurations.

SD WAN creates standardisation.  The template is contained within the platform, removing the spectre of an engineer designing a new configuration for a site. With SD WAN all elements of the configuration will be centrally issued by the orchestrator, so there is very little for the Commissioning Engineer to configure on a deployment once the business intent overlays are setup.

SD WAN configuration is more intuitive than with a traditional WAN because it uses a Graphical User Interface (GUI) rather than producing lines of code. Although configuring by GUI is available for many Cisco products, the GUI for traditional WAN routers is less comprehensive and still requires using CLI to complete the config.

SD WAN can reduce deployment costs by separating the activities of different skill levels

SD WAN can reduce the cost of deployment by separating the activities of a highly skilled Design Engineer followed by a less skilled Commissioning Engineer when each site goes live.

This works on the basis that a senior engineer will be needed for the template designs and then applying individual site-specific information such as IP Addresses and subnets.

Since the router downloads the config from the cloud, then there shouldn’t need to be a senior engineer on hand for when the install is taking place. Installs should be plug and play.

SD WAN adds consistency throughout project delivery, making the network easier to manage.

With a traditional WAN, one might deliver the first couple of sites with a certain understanding of how the configuration will work. Then something changes with the requirements or something isn’t working as well as it should, so the config is tweaked for the next few sites. However, if time isn’t taken (or available) to go back and change the other sites then the estate will end up with a mismatch of config styles. This can also be caused by a software level changing – what worked on one version of the IOS no longer works on the new.

With SD WAN, if the config needs to change, the template can be changed and then all devices that have that config will be updated remotely.

SD WAN can add consistency across all networks by removing Carrier anomalies

Sometimes mismatches can happen when different carriers are used. For instance:

  • Some networks use IP Precedence to mark packets and some DSCP
  • While layer 2 networks will use 802.1p values.
  • Some Carriers specify a percentage of the access for Class of Service, while some specify an actual amount. When you upgrade circuits then the CoS allowance increases with one but not the other unless you remember to modify it.

SD WAN takes control of the CoS and prioritisation and doesn’t need to interact with the Carrier’s CoS so networks can be delivered consistently regardless of the Carrier.

SD WAN can add consistency across all networks by removing individual engineer design preferences

With a traditional WAN there are a number of ways to configure a device for the same end goal, which can lead to different engineers having different preferences and styles.  This can cause problems when engineers don’t understand each other’s styles, and cause a long-term knock-on effect for In-Life management.

With SD WAN you design Business Intent Overlays which effectively create the configuration. Since these Overlays are saved as templates, a change in Design Engineer won’t lead to a change in template designs.

SD WAN won’t require an Engineer install and could be self-install

Many SD WAN vendors claim that they provide zero touch deployments. This can be true but not in all cases.

When first deployed to site, the SD WAN device first needs to obtain an IP Address. With Internet Broadband this is likely to be DHCP, so the network will give the device this address. With private networks or Internet with Static IP, an engineer or your managed service provider will have applied this to the device before it is sent out.

The device, then calls home over the internet, using DNS, before being assigned to the SD WAN central orchestrator.

It’s perfectly feasible for the device to call home once plugged in, but some businesses are not happy for their own staff to do this.  If you have relied on a managed engineer install in the past, then you may not be prepared (or resourced) to have a zero touch deployment at every site.

What we can say is that there is only a basic config required to get up and running.  Once your IT team or Managed Service Provider has access, they can initiate the full configuration to be applied – in which case a technical courier would be sufficient.