ACI: Two basic questions.

Posted:  Dec 15th, 2014 Authors: Chad Hintz and Cesar Obediente                                                 

In the past year we have done several ACI presentations to different customers in different segments.  But lately, the main two questions that consistently arise from customers are:

·      How “Open” is ACI?

·      How much does ACI cost?

We thought it was appropriate to address these two issues on this blog to serve as a reference for our customers and partners.

In addressing the “How Open is ACI” question, we first need to understand that ACI is designed as a "system" and must be understood as a complete solution that provides the ability for customers to define their Application Network Policy (APN) in order to speed the deployment of applications into the network while helping customers automate their network, something that has been missing in the network.

If we look a little closer regarding how ACI addresses the openness question, we are going to break into different sessions:

• Northbound
• ACI provides a full range of RESTful API in order for 3^rd party applications like Splunk, Tivoli, etc and Cloud Management Systems (CMS) like Openstack, VCAC and Cloudstack to be able to collect information and configure the ACI Controller (APIC).  APIC supports two data formats such as JSON and XML.
• Customer and 3^rd party partners are encouraged to visit http://developer.cisco.com/site/apic-dc

• Connecting to the Fabric
• ACI allows for any 3^rd party switch, router to connect to the ACI fabric via standard routing protocols such as OSPF and BGP.
• ACI provides the flexibility for customers to attach to the fabric via any hypervisor such as ESXi, Hyper-V, KVM, while adding the flexibility for customers to connect containers.
• ACI allows customers to connect any workload to the fabric via bare-metal or virtual machines.
• ACI allows customers to choose the best of breed when it comes L4-L7 services, where customers can make the decision to connect any vendor appliance as a physical or virtual appliance via the device package option. 
• http://www.cisco.com/c/en/us/solutions/collateral/data-center-virtualization/application-centric-infrastructure/solution-overview-c22-732445.html
• Cisco ACI allows any type of IP storage to be connected to the fabric.

• Inside the Fabric
• Inside the fabric ACI leverages standard protocols like VxLAN, ISIS, BGP and OPFLEX
• At the moment the N9K is the only platform in the industry that is capable of being part of the ACI fabric. The main reason is because the N9K has some unique capabilities in their ASIC to provide specific functions within the fabric.  We have covered some of these functionalities in previous blogs.

Figure 1 shows the openness of ACI and how ACI addresses the customer’s concerns with regards to how open ACI is.

Figure 1

The second topic we would like to address in this post is: how much does ACI cost?  During our presentations to our customers, we have explained that they need to think about two different “costs”:

• The Underlay Cost: this is the cost of the physical infrastructure such as switches, optics and cable
• The Overlay Cost: this is the cost of providing a virtual overlay

To better understand this concept, we are going to taking into consideration a design:

• 4 Way Spine
• 100 ToR.
• Oversubscription ratio of  2:1
• Each ToR has 32 attached servers with an average of 30 VMs per port

This design is very common for medium to large customers, which equates to about 96,000 VMs per fabric.  Below we are going to compare how much it costs to build an ACI fabric vs building merchant silicon fabric as the underlay and an overlay technology such as NSX or Nuage.  Disclaimer: the pricing we are going to be using for this comparison is “List Pricing”.

Cisco ACI Configuration

Merchant Silicon

NOTE: We will be using Arista as the Underlay

Now we need to add the cost of the overlay to the Arista underlay.  Unfortunately, we don’t have a precise list price for the overlay since we have heard ranges from $1-$50 per VM per month.  We also have heard that some vendors are including this overlay cost in their Enterprise License Agreement (ELA).  

Therefore, if we take the low end of the spectrum for this exercise which is $1 per VM per Month, and follow the same model as above with 96,000 VMs per fabric,  this would equate to $96,000 per month or $1,152,000 per year or $5,760,000 over a 5-year period.  

We also need to include the cost of the servers that are required in order to run the overlay (Controllers, Gateways, etc). Unfortunately, we don't have an actual model on how many servers are require to run this type of solution but we have been told a good rule of thumb is to have about 5% of compute in the overall solution. In this particular case we need to add 80 servers to satisfied this solution. Because of the many variables we decided to leave it off. But customers should take into consideration this extra cost.  

Adding the Arista underlay with the overlay cost, the total cost of the solution over a 5-year period is going to be $12,602,760.

As you can see from this analysis. the gap between Cisco ACI vs Merchant Silicon (Arista) + Overlay is $7,355,023.  That’s a pretty significant figure for any customer that is considering building a private cloud.

Summary Table

Below are couple samples config where it show medium to large fabric and another sample for small fabric.  These comparisons are showing the true saving of a convergence overlay/underlay vs a desegregated solution.

Closing

In closing, having an integrated solution in your network which includes the Overlay and Underlay is not only beneficial from a technical point that we have explained in previous post but it also makes sense from a financial point of view.

Bonus Material

Here is our interview with Soni Jiandani.  Soni is the Senior Vice President of the Insieme Business Group in Cisco.  She well recognized with over 20 years of experience in the switching industry and has been part of numbers of project in Cisco including the Catalyst 5000, Catalyst 6000, Andiamo, Nuova and most recently part of founding team of Insieme.