Category Archives: Multi-Cloud

Bringing Reference Architectures to Multi-Cloud Networking

Recently I attended Aviatrix Certified Engineer training to better understand multi-cloud networking and how Aviatrix is trying to solve its many problems, some of which I have experienced first-hand. Disclaimer: Since 2011, I’ve been an avid listener of the Packet Pushers podcast, where Aviatrix has sponsored 3 shows since December 2019.

Ever since I embarked on the public cloud journey, I have noticed how each of the big 4 vendors (AWS, Azure, GCP, and OCI) approach networking in the cloud differently from how it has been done on-premises. They all have many similarities, such as:

  • The concept of a virtual Data Center (VPC in AWS and GCP, VNET in Azure, VCN in OCI).
  • Abstracting Layer 2 as much as possible (no mention of Spanning Tree or ARP anywhere) from the user despite the fact that these protocols never went away.

However, there are many differences as well, such as this one:

  • In AWS, subnets have zonal scope – each subnet must reside entirely within one Availability Zone and cannot span zones.
  • In GCP, subnets have regional scope – a subnet may span multiple zones within a region.

Broadly speaking, the major Cloud Service Providers (CSPs) do a fairly decent job with their documentation, but they don’t make it easy for one to connect clouds together. They give you plenty of rope to hang yourself, and you end up being on your own. Consequently, your multi-cloud network design ends up being unique – a snowflake.

In the pre-Public Cloud, on-premises world, we would never have gotten far if it weren’t for reference designs. Whether it was the 3-tier Core/Aggregation/Access design that Cisco came out with in the late 1990’s, or the more scaleable spine-leaf fabric designs that followed a decade later, there has always been a need for cookie-cutter blueprints for enterprises to follow. Otherwise they end up reinventing the wheel and being snowflakes. And as any good networking engineer worth their salt will tell you, networking is the plumbing of the Internet, of a Data Center, of a Campus, and that is also true of an application that needs to be built in the cloud. You don’t appreciate it when it is performing well, only when it is broken.

What exacerbates things is that the leading CSP, AWS, does not even acknowledge multiple clouds. In their documentation, they write as if Hybrid IT only means the world of on-premises and of AWS. There is only one cloud in AWS’ world and that is AWS. But the reality is that there is a growing need for enterprises to be multi-cloud – such as needing the IoT capabilities of AWS, but some AI/ML capabilities of GCP; or starting on one cloud, but later needing a second because of a merger/acquisition/partnership. Under such circumstances, an organization has to consider multi-cloud, but in the absence of a common reference architecture, the network becomes incredibly complex and brittle.

Enter Aviatrix with its Multi-Cloud Network Architecture (MCNA). This is a repeatable 3-layered architecture that abstracts all the complexity from the cloud-native components, i.e. regardless of the CSPs being used. The most important of the 3 layers is the Transit Layer, as it handles intra-region, inter-region, and inter-cloud connectivity

Aviatrix Multi-Cloud Networking Architecture (MCNA)

Transitive routing is a feature that none of the CSPs support natively. You need to have full-mesh designs that may work fine for a handful of VPCs. But it is an N² problem (actually N(N-1)/2), which does not scale well in distributed systems. In AWS, it used to be that customers had to be able to address this completely on their own with Transit VPCs, which was very difficult to manage. In an attempt to address this problem with a managed service, AWS announced Transit Gateways at re:Invent 2018, but that doesn’t solve the entire problem either. With Transit Gateways (TGW), a peered VPC sends it routes to the TGW it is attached to. However, that TGW does not automatically redistribute those routes to the other VPCs that are attached to it. The repeatable design of the Aviatrix MCNA is able to solve this and many other multi-cloud networking problems.

Aviatrix has a broad suite of features. The ones from the training that impressed me the most were:

  • Simplicity of solution – This is a born-in-the-cloud solution whose components are:
    • a Controller that can even run on a t2.micro instance
    • a Gateway that handles the Data Plane and can scale out or up
    • Cloud native constructs, such as VPC/VNET/VCN
  • High Performance Encryption (HPE) – This is ideal for enterprises who, for compliance reasons, require end-to-end encryption. Throughput for encrypting a private AWS Direct Connect, Azure ExpressRoute, GCP Cloud Interconnect, or OCI FastConnect link cannot exceed 1.25 Gbps because virtual routers utilize a single core and establish only 1 IPSec tunnel. So even if you are paying for 10 Gbps, you are limited by IPSec performance and get only 1.25 Gbps performance. Aviatrix HPE is able to achieve line-rate encryption using ECMP.
  • CloudWAN – This takes advantage of the existing investment that enterprises have poured into Cisco WAN infrastructure. When such organizations need to connect to the cloud with optimal latency between branches and apps running in the cloud, Aviatrix CloudWAN is able log in to these Cisco ISRs, and configure VPN and BGP appropriately so that they connect to an Aviatrix Transit Gateway with the AWS Global Accelerator service for the shortest latency path to the cloud.
  • Smart SAML User VPN – I wrote a post on this here.
  • Operational Tools – FlightPath is the coolest multi-cloud feature I have ever seen. It is an inter-VPC/VNET/VCN troubleshooting tool that retrieves and displays Security Groups, Route table entries, and Network ACLs along all the cloud VPCs through which data traverses so you can pinpoint where a problem exists along the dataplane. This would otherwise involve approximately 25 data points to investigate manually (and that doesn’t even include multi-cloud, multi-region, and multi-account). FlightPath automates all of this. Think Traceroute for multi-cloud.

In the weeks and months to come, I’m hoping to get my hands wet with some labs and write about my experience here.