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Data Center

In the dynamic landscape of Data Center architecture, growth is inevitable. Sooner or later, organizations find themselves managing multiple Data Centers, each housing critical components of their digital infrastructure. The challenge then becomes establishing a seamless, reliable, and scalable means of communication between these dispersed centers.

Enter EVPN-VxLAN with DCI (Data Center Interconnect). This dynamic duo serves as the linchpin for connectivity, providing a swift, dependable, and scalable solution to bridge the gaps between Data Centers. As the digital footprint expands, the need for a sophisticated network that facilitates secure and efficient communication becomes paramount.

Before extending the reach of your EVPN-VxLAN architecture to interconnect Data Centers seamlessly, the crucial first move is establishing an underlay connectivity between these sites. This is where the journey begins, contemplating the right approach for a Data Center Interconnect (DCI).

There are a couple of approaches:

  1. Dark Fiber or Leased Line.
  2. EVPL (Ethernet Virtual Private Line)
  3. Service Provider MPLS L3VPN
  4. DCI over Public Internet

In this article we are going to discuss the cheapest, and quickest solution in this case, which is DCI over the Public Internet. This option introduces a layered approach that imposes overhead on the IP packets and adds a layer of complexity. In simple terms, it means establishing one or multiple(usually this is the case for redundancy purposes) tunnels(something like IPIP, GRE or IPSec for encrypted traffic) between the two Data Centers. Then, use it to extend the underlay connectivity of each Data Center, therefore facilitating the main requirement for EVPN-VxLAN, which is connectivity between the loopbacks of IP Fabric components.

At first glance, it looks simple, but let’s take a look deeper into the packets and understand what is actually happening under the hood, what problems may occur, what do you have to know before moving forward with this approach and what pros and cons do we have for this solution.

A quick view over the packet that is flowing between the Data Centers:


1️⃣ Cost-Effective Scalability:

  • Pro: Leveraging the Internet for DCI in EVPN-VXLAN architecture can be cost-effective, especially compared to dedicated private lines.

2️⃣ Global Reach:

  • Pro: Internet-based DCI provides a wide-reaching solution, enabling connectivity between geographically dispersed data centers.

3️⃣ Flexibility and Agility:

  • Pro: The approach offers flexibility and agility in connecting data centers, making it suitable for dynamic and evolving network requirements.


1️⃣ Security Concerns:

  • Con: Transmitting data over the public Internet raises security concerns, and additional measures such as encryption become imperative.

2️⃣ Variable Performance:

  • Con: Internet-based connectivity may exhibit variable performance, subject to fluctuations in Internet traffic, leading to potential latency and jitter issues.

3️⃣ Fragmentation Challenges:

  • Con: VxLAN packets can’t be fragmented, and if fragmentation is required over the Internet, it adds complexity in terms of device capabilities and packet reassembly.

4️⃣ Reliability Dependencies:

  • Con: Reliability is dependent on the public Internet, and factors like outages or congestion may impact the overall stability of the DCI.

5️⃣ QoS Limitations:

  • Con: Quality of Service (QoS) mechanisms may be limited over the Internet, impacting the ability to prioritize critical traffic.

Understanding these intricacies is vital for navigating the challenges and optimizing performance in Data Center Interconnect scenarios over the Internet. Diving deeper into these network architectures is key to ensuring a robust and efficient infrastructure.

At ITcare we have dealt with multiple DCI approaches, and in the next set of articles we are going to explore what additional solutions you may have for the DCI and what pros and cons each of thus has.

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