What is Multi-Cloud Networking?

Multi-cloud networking (MCN), as a technology, aims to provide easy network connectivity between cloud environments. For the purpose of our definition, we need to imagine our datacenter as a cloud. You can loosely define a cloud environment as 'anywhere you run workloads.' The concept is nebulous… literally. Clouds come in all shapes and sizes, from 'running on Pi' to AWS / GCP / Azure. MCN is to clouds, as Internet is to network.

AWS’s DirectConnect, Azure ExpressRoute and GCP’s Direct Link were early forms of MCN, aimed at joining portions of their own clouds together with customer datacenters.

Insertion of transport virtual appliances in clouds has become another mechanism for MCN through time. Its strength is its flexibility and agility.

One other notable MCN concept is the transport provider. Some circuit providers offer 'short-hop' transport to various cloud providers by routing. This option offers significant throughput versus the SDN router but lacks the agility. This is a popular option for hybrid cloud enterprises. With all of these options, you can make individual connections to each cloud, potentially in a hub and spoke fashion or full mesh.

Challenges With Multi-Cloud Networking

The top-most concern should be scalability, in every way. You need to be concerned about scale in routing, licensing, metered cloud costs, not to mention the knowledge to understand all of the nuance features of each cloud provider and so many more things. All of this is operational overhead, which can be significant.

Another serious challenge is IP addressing. The sheer volume of it is one thing. Anyone who works with modern applications today can tell you that it's hard to even find a workload sometimes, with how massive things can get. DNS is one possible option to assist, but you've got to account for all of the native cloud workloads, too.. with their different DNS interfaces.

Another common challenge is IP overlap. If you're curious what I mean, lets say your employer acquires a piece of software that lives in GCP, but you're already in AWS. You start going down the path of routing when you suddenly notice that both cloud environments are 10.1.x.x/16. This means localized routing all over the place and we know how much router people love one-offs, am I right?

The next challenge is one I've already hinted at: How many indepth nerd knobs do you want to know by how many security vendors? You've got to strategize to minimize this sort of potential sprawl and standardize on the vendors that can do the most for you.

Advantages of Multi-Cloud Networking

The greatest advantage is really multi-cloud transit. Understanding so many different and new technologies is a daunting task. With multi-cloud transit, data centers route through the same SDN routers as your cloud application flows, allowing you to see each cloud provider as a metered resource for app consumption. No need to worry about addressing, DNS, or routing for each environment.

Another substantial benefit is the enablement of a shared security model. When you can route between these environments, you can also easily aggregate logs, integrate with SIEMs and manage automated security policies with ease.

Network fluidity is another substantial benefit. When your COO comes to you and says that you need to integrate a newly acquired network segment, you have no problems. One of the very cool benefits of SDN is the ability to route by software object. When we think of routing in traditional networks we want our packet to get to 10.10.10.4 by way of 192.168.3.1, but an SDN router sends our packet to 10.10.10.4 by way of f5xc_gcp_router4. This also means that your app developer can stamp out their app in AWS to send another packet to 10.10.10.4 by way of f5xc_aws_router16 or such. Overlap no longer matters when you route through an SDN core.

Conclusion

Giving your modern application networks the flexibility to grow on demand, to assimilate new application network segments in minutes instead of months...

Ultimately, I really believe that MCN - when done right - like Chuck Mangione said (well, with a flugel horn), 'Feels So Good.' The designs you can build with it are SO much more scalable and translate everything from physical data centers to clouds in a clean, easy to manage fashion.