How to Lower CDN Bills While Improving Performance
July 19, 2015 | Robert Gibb
Multi-CDN has been a hot topic of discussion in 2015. It’s also often the path to reducing content delivery costs and gaining more confidence in your CDN strategy.
But lower CDN bills and better performance? It seems too good to be true. However, since load balancing services have become available, it’s actually very possible, and very easy. Just take a look at how jsDelivr load balances 81 locations, 19 of them being MaxCDN edge servers.
If you need a refresher on multi-CDN before we move forward, these resources will help:
How Do More Services Cost Less?
To lower CDN costs and improve performance, you need at least two services in addition to the CDN you’re already using. First, you need a CDN that costs less than your current one. Second, you need a load balancing service to intelligently distribute traffic between your current CDN and new one. This new CDN should also have comparable or better performance and customer support than your original.
Note: You can create your own load balancing system, but using ready-made load balancing services is usually preferred.
Example of Potential Savings
For the sake of simplicity, below we’re going to show how much potential CDN savings you could earn given you use 100TB of CDN bandwidth per month. Keep in mind though that savings often increase when you use more bandwidth as part of a multi-CDN strategy.
|CDNs used?||CDN-1 ($0.08/GB)|
In the current scenario, there is one price paid to one provider. There is also no load balancing occurring. So if the CDN goes down, no other CDN can take its place.
|CDNs used?||CDN-1 ($0.08/GB) and CDN-2 ($0.04/GB)|
|Load balanced?||Yes (50/50 Split)|
By load balancing CDN-2 with CDN-1, there is a savings of 25% (not including the cost of load balancing). Another benefit of this cost-savings scenario is having the ability to route all traffic to CDN-2 should CDN-1 go down.
Note: The 50/50 split in the cost-savings scenario assumes that when the two CDNs are load balanced – based on performance or by manually binding individual countries to separate CDNs – the bandwidth split is perfect. This makes it easier to understand potential savings.
Additional Costs to Consider
In the tables above, extra costs for HTTP and HTTPS requests charged by CDN-1 and similar content delivery networks are not accounted for. Neither are charges for SSL and engineering support.
To see how much top CDNs charge for these things, check out this quick CDN comparison sheet. You’ll find that you can save on bandwidth costs by taking a multi-CDN approach, as well as SSL and support costs.
Another cost to consider is the cost of the load balancing service. Unlike content delivery networks that charge mainly based on bandwidth, load balancing services charge based on hits. So before getting quotes from different providers, use your CDN’s analytics to find out how many hits you average per month.
Note: MaxCDN does NOT charge for requests. We also offer shared SSL for free and dedicated SSL for as low as $250/month.
The Beauty of Competition
By adding another CDN to your content delivery strategy, you incent your initial provider to lower costs. Pete Mastin of Cedexis illustrates this point quite well in his LinkedIn post titled Cloud and CDN Vendor Diversity for Cost Containment.
According to Mastin:
“If your CDN vendor thinks they have you locked in – then there is no incentive to reduce your rate in year 2 or year 3. Everyone knows the price of transit is going down year over year. This has been well documented over the last 20 years. So why doesn’t my rate go down?! Get a second vendor in there and you will see it drop. For sure.
“Vendor lock-in is the main factor in not getting price concessions on your CDN rates. Value added services will typically not see the price erosion that your CDN transit rates will – but by getting another vendor in there that can provide similar value added services, your primary CDN provider is incented to give you better pricing.”
3 More Ways to Lower CDN Costs
In addition to significantly reducing CDN costs and improving performance with a multi-CDN strategy, there are other ways to lower CDN costs. They won’t necessarily improve performance, but they will impact your monthly spend.
Use CDN-2 for 100% of Traffic
In the graph below, Cedexis illustrates the S curve. According to Cedexis, it shows that “given any two CDNs, what portion of the audience would have benefited from being on one CDN versus the other.” The remaining percentage of the audience would have fared equally as well on either CDN.
You can use this S-curve tactic to measure the performance of CDN-1 and CDN-2 if you are load balancing. If the split is often in favor of CDN-2, or the CDN that performs well and costs less, you could consider relying primarily on CDN-2 to serve traffic. And to ensure uptime, you could keep CDN-1 as a failover CDN.
Test Different Load Balancing Providers
Just as different CDNs are subject to different pricing structures, the same is true for load balancing services. As previously mentioned, providers of these services charge on hits rather than bandwidth. So before shopping around for a different provider, find out how many hits you average per month. Often analytics from your CDN can help you with this.
Unfortunately, there is no model for “load balancing” a load balancer 🙂
The pricing model throughout the entire CDN industry is the same: The more bandwidth you use, the less you pay. Obviously lower CDN prices shouldn’t be an incentive to grow your business, but they are a nice little perk when your business’s content does reach that next level of exposure.
If your business has grown considerably over the past few years but you are still paying the same cost-per-GB since your contract started, ask your CDN provider if your current usage is eligible for placement under a different pricing tier. This could save you hundreds, if not thousands, and all it takes is one call. You can also check your provider’s pricing page as some CDNs do make their making pricing tiers visible.
If you have any questions related to CDN costs or the relationship between CDN costs and performance, please leave a comment below.