WAN Virtualization

WAN Virtualization

 

 

WAN Virtualization

Organizations constantly seek innovative solutions in modern networking to enhance their network infrastructure and optimize connectivity. One such solution that has gained significant attention is WAN virtualization. In this blog post, we will delve into the concept of WAN virtualization, its benefits, and how it revolutionizes how businesses connect and communicate.

WAN virtualization, also known as Software-Defined WAN (SD-WAN), is a technology that enables organizations to abstract their wide area network (WAN) connections from the underlying physical infrastructure. It leverages software-defined networking (SDN) principles to decouple network control and data forwarding, providing a more flexible, scalable, and efficient network solution.

 

Highlights: WAN Virtualization

  • VPN and SDN Components

So, what is WAN virtualization? WAN virtualization is an essential technology in the modern business world. It creates virtualized versions of wide area networks (WANs) – networks spanning a wide geographic area. The virtualized WANs can then manage and secure a company’s data, applications, and services.

Regarding implementation, WAN virtualization requires using a virtual private network (VPN), a secure private network accessible only by authorized personnel. This ensures that only those with proper credentials can access the data. WAN virtualization also requires software-defined networking (SDN) to manage the network and its components.

 

Before you proceed, you may find the following posts helpful:

  1. SD WAN Overlay
  2. Generic Routing Encapsulation
  3. WAN Monitoring
  4. SD WAN Security 
  5. Container Based Virtualization
  6. SD WAN and Nuage Networks

 



WAN Virtualization

Key WAN Virtualization Discussion Points:


  • Introduction to WAN Virtualization and what is involved.

  • Highlighting the issues around internet traffic left to its defaults.

  • Critical points on WAN utilization problems.

  • Technical details on routing protocol convergence.

  • Technical details on SD WAN Overlay and how this changes the WAN.

 

Back to Basics: WAN virtualization.

WAN Challenges

Deploying and managing the Wide Area Network (WAN) has become more challenging. Engineers face several design challenges, such as traffic flow decentralizing, inefficient WAN link utilization, routing protocol convergence, and application performance issues with active-active WAN edge designs. Active-active WAN designs that spray and pray over multiple active links present technical and business challenges.

To do this efficiently, you have to understand application flows. There may also be performance problems. When packets get to the other end, there may be out-of-order packets as each one of the links propagates at different speeds. The remote end has to reassemble and put back together, causing jitter and delay. Both high jitter and delay are bad for network performance. To recap on WAN virtualization, including the drivers for SD-WAN, you may follow this SD WAN tutorial.

What is WAN Virtualization
Diagram: What is WAN virtualization? Source Linkedin.

 

SD-WAN vs. DMVPN

Two popular WAN solutions are DMVPN and SD-WAN.

DMVPN (Dynamic Multipoint Virtual Private Network) and SD-WAN (Software-Defined Wide Area Network) are popular solutions to improve connectivity between distributed branch offices. DMVPN is a Cisco-specific solution, and SD-WAN is a software-based solution that can be used with any router. Both solutions provide several advantages, but there are some differences between them.

DMVPN is a secure, cost-effective, and scalable network solution that combines underlying technologies and DMVVPN phases (for example, the traditional DMVPN phase 1 ) to connect multiple sites. It allows the customer to use existing infrastructure and provides easy deployment and management. This solution is an excellent choice for businesses with many branch offices because it allows for secure communication and the ability to deploy new sites quickly.

SD-WAN is a software-based solution that is gaining popularity in the enterprise market. It provides improved application performance, increased security, and improved network reliability. SD-WAN is a great choice for businesses that require high-performance applications across multiple sites. It provides an easy-to-use centralized management console that allows companies to deploy new sites and manage the network quickly.

 

 

Dynamic Multipoint VPN
Diagram: Example with DMVPN. Source is Cisco
  • A key point: Lab on DMVPN operating over the WAN

The following show DMVPN operating over the WAN. The SP node represents the WAN network. Then we have R11 as the hub and R2, R3 as the spokes.  The DMVPM network over the WAN is made possible with several protocols. We have GRE; in this case, the tunnel destination is specified as a point-to-point GRE tunnel instead of a mGRE tunnel.

Then we have NHRP that this used to help create a mapping as this is a nonbroadcast network; we can not use ARP. So, we need to manually set this up on the spokes with the command: ip nhrp NHS 192.168.100.11

DMVPN configuration
Diagram: DMVPN Configuration.

 

Shift from network-centric to business intent.

The core of WAN virtualization involves shifting focus from a network-centric model to a business intent-based WAN network. So instead of designing the WAN for the network, we can create the WAN for the application. This way, the WAN architecture can simplify application deployment and management.

First, however, the mindset must shift from a network topology focus to an application services topology. A new application style consumes vast bandwidth and is very susceptible to variations in bandwidth quality. Things such as jitter, loss, and delay impact most applications, which makes it essential to improve the WAN environment for these applications.

wan virtualization
Diagram: WAN virtualization.

 

The spray and pray method over two links increase bandwidth but decreases “goodput.” It also affects firewalls as they will see asymmetric routes. When you want an active-active model, you need application session awareness and a design that eliminates asymmetric routing. It would help if you could slice the WAN properly so application flows can work efficiently over either link.

 

What is WAN Virtualization: Decentralizing Traffic

Decentralizing traffic from the data center to the branch requires more bandwidth to the network’s edges. As a result, we see many high-bandwidth applications running on remote sites. This is what businesses are now trying to accomplish. Traditional branch sites usually rely on hub sites for most services and do not host bandwidth-intensive applications. Today, remote locations require extra bandwidth, which is not cheaper yearly.

 

Inefficient WAN utilization

Redundant WAN links usually require a dynamic routing protocol for traffic engineering and failover. Routing protocols require complex tuning to load balance traffic between border devices. Border Gateway Protocol (BGP) is the primary protocol for connecting sites to external networks.

It relies on path attributes to choose the best path based on availability and distance. Although these attributes allow granular policy control, they do not cover aspects relating to path performance, such as Round Trip Time (RTT), delay, and jitter.

Furthermore, BGP does not always choose the “best” path, while the “best” path may have different meanings for customers. For example, customer A might consider the path via provider A as the best due to the price of links. Default routing does not take this into account. Packet-level routing protocols are not designed to handle the complexities of running over multiple transport agnostic links. Therefore, a solution must arise that eliminates the need for packet-level routing protocols.

BGP Path Attributes
Diagram: BGP Path Attributes Source is Cisco.

 

Routing protocol convergence

WAN designs can also be active standby, which requires routing protocol convergence in the event of primary link failure. However, routing convergence is slow, and to speed up, additional features, such as Bidirectional Forwarding Detection (BFD), are implemented that may stress the network’s control plane. Although mechanisms exist to speed up convergence and failure detection, there are; still several convergence steps, such as:

Rouitng Convergence

Convergence


Detect


Describe


Switch 


Find

 

Branch office security

With traditional network solutions, branches connect back to the data center, with the data center typically providing Internet access. The application world has evolved, and branches directly consume applications such as Office 365 in the cloud. This drives a need for branches to access these services over the Internet without going to the data center for Internet access or security scrubbing.

Extending the security diameter into the branches should be possible without requiring onsite firewalls / IPS and other security paradigm changes. A solution must exist that allows you to extend your security domain to the branch sites without costly security appliances at each branch—essentially, building a dynamic security fabric.

 

WAN Virtualization

The solution to all these problems is SD-WAN ( software-defined WAN ). SD-WAN is a transport-independent overlay software-based networking deployment. It uses software and cloud-based technologies to simplify the delivery of WAN services to branch offices. Similar to Software Defined Networking (SDN), SD-WAN works by abstraction. It abstracts network hardware into a control plane with multiple data planes to make up one large WAN fabric.

 

 SD-WAN in a nutshell 

At a basic level, when we consider the Wide Area Network (WAN) environment, we connect data centers to several branch offices to deliver packets between those sites, supporting the transport of application transactions and services. SD-WAN platform allows you to pull Internet connectivity into those sites, becoming part of one large transport-independent WAN fabric.

SD-WAN monitors the paths and the application performance on each link (Internet, MPLS, LTE ) and chooses the best path based on performance.

There are many forms of Internet connectivity (cable, DSL, broadband, and Ethernet). They are quick to deploy at a fraction of the cost of private MPLS circuits. SD-WAN provides the benefit of using all these links and monitoring which is best for what applications.

Application performance is continuously monitored across all eligible paths-direct internet, internet VPN, and private WAN. It creates an active-active network and eliminates the need to use and maintain traditional routing protocols for active-standby setups—no reliance on the active-standby model and associated problems.

WAN virtualization
Diagram: WAN virtualization. Source is Juniper

 

SD-WAN simplifies WAN management

SD-WAN simplifies managing a wide area network by providing a centralized platform for managing and monitoring traffic across the network. This helps reduce the complexity of managing multiple networks, eliminating the need for manual configuration of each site. Instead, all of the sites are configured from a single management console.

SD-WAN also provides advanced security features such as encryption and firewalling, which can be configured to ensure that only authorized traffic is allowed access to the network. Additionally, SD-WAN can optimize network performance by automatically routing traffic over the most efficient paths.

what is wan virtualization

SD WAN Packet Steering

SD-WAN packet steering is a technology that efficiently routes packets across a wide area network (WAN). It is based on the concept of steering packets so that they can be delivered more quickly and reliably than traditional routing protocols. Packet steering is crucial to SD-WAN technology, allowing organizations to maximize their WAN connections.

SD-WAN packet steering works by analyzing packets sent across the WAN and looking for patterns or trends. Based on these patterns, the SD-WAN can dynamically route the packets to deliver them more quickly and reliably. This can be done in various ways, such as considering latency and packet loss or ensuring the packets are routed over the most reliable connections.

Spraying packets down both links can result in 20% drops or packet reordering. SD-WAN makes packets better utilized, no reorder, and better “goodput.” SD-WAN increases your buying power and results in buying lower bandwidth links and running them more efficiently. Over-provision is unnecessary as you are using the existing WAN bandwidth better.

 

Benefits of WAN Virtualization:

1. Enhanced Network Performance: WAN virtualization allows organizations to optimize network performance by intelligently routing traffic across multiple WAN links. Organizations can achieve improved application performance and reduced latency by dynamically selecting the most efficient path based on real-time network conditions.

2. Cost Savings: Traditional WAN solutions often require expensive dedicated circuits for each branch office. With WAN virtualization, organizations can leverage cost-effective internet connections, such as broadband or LTE, while ensuring secure and reliable connectivity. This flexibility in choosing connectivity options can significantly reduce operational costs.

3. Simplified Network Management: WAN virtualization provides centralized management and control of the entire network infrastructure. This simplifies network provisioning, configuration, and monitoring, reducing traditional WAN deployments’ complexity and administrative overhead.

4. Increased Scalability: WAN virtualization offers the scalability to accommodate evolving network requirements as organizations grow and expand their operations. It allows for the seamless integration of new branch offices and additional bandwidth without significant infrastructure changes.

5. Enhanced Security: With the rise in cybersecurity threats, network security is paramount. WAN virtualization enables organizations to implement robust security measures, such as encryption and firewall policies, across the entire network. This helps protect sensitive data and ensures compliance with industry regulations.

  • A final note on what is WAN virtualization

Server virtualization and automation in the data center are prevalent, but WANs are stalling in this space. It is the last bastion of hardware models that has complexity. Like hypervisors have transformed data centers, SD-WAN aims to change how WAN networks are built and managed. When server virtualization and hypervisor came along, we did not have to worry about the underlying hardware. Instead, provision a Virtual Machine (VM) and run an application of choice. Today’s WAN environment requires you to manage details of carrier infrastructure, routing protocols, and encryption. 

 

  • SD-WAN pulls all WAN resources together and slices up the WAN to match the applications on them.

 

The Role of WAN Virtualization in Digital Transformation:

In today’s digital era, where cloud-based applications and remote workforces are becoming the norm, WAN virtualization is critical in enabling digital transformation. It empowers organizations to embrace new technologies, such as cloud computing and unified communications, by providing secure and reliable connectivity to distributed resources.

Conclusion:

WAN virtualization is transforming how organizations connect and communicate in the digital age. By providing enhanced network performance, cost savings, simplified management, scalability, and improved security, it offers a compelling solution for businesses of all sizes. As the demand for agile and efficient network infrastructures continues to grow, WAN virtualization will undoubtedly remain at the forefront of network technology advancements, empowering organizations to unlock the full potential of their network connectivity.