This lesson goes into great detail about Dynamic Multipath Optimization (DMPO) and how the VMware SD-WAN service uses it.
Enterprises and service providers are able to utilize several WAN transports simultaneously with the help of VMware SD-WAN, which is a solution. In this manner, they are able to enhance bandwidth and guarantee the functioning of the program. On-premises applications as well as cloud-based apps (SaaS/IaaS) are compatible with the solution. A Cloud-Delivered architecture is utilized, which results in the construction of an overlay network that has numerous tunnels. Real-time monitoring and adaptation to changes in WAN transports are performed by it. Dynamic Multipath Optimization, often known as DMPO, is a technique that was developed by VMware SD-WAN in order to make the overlay network more resilient. It takes into account the behaviour of the wide area network links in real time. The most important characteristics and advantages of DMPO are outlined in this document.
Important Features
VMware SD-WAN processes and forwards data traffic using the DMPO technology. It functions as a bridge between the VMware SD-WAN Edge and Gateway devices. The DMPO endpoints are these devices.
- In the case of enterprise locations (Branch to Hub or Branch to Branch), the Edges establish mutual DMPO tunnels.
- Each Edge establishes DMPO tunnels with one or more Gateways for cloud applications.
Below are the three main characteristics of DMPO.
- Continuous Monitoring
- Advanced/Automated Bandwidth Discovery: When the VMware SD-WAN Edge finds a WAN link, it sets up DMPO connections with one or more VMware SD-WAN Gateways and then tests the bandwidth with the nearest Gateway. To do the bandwidth test, short bursts of two-way data are sent and the received rate is checked at both ends. The Gateway is set up at the points of presence (PoPs) of the internet, so it can also find the real public IP address of the WAN link if the Edge interface is hidden by a NAT or PAT device. For a private link, the steps are the same. The WAN bandwidth is set in stone for the Edges that act as the Hub or headend. After setting up a DMPO tunnel with the Hub Edges, the branch Edge and the Hub Edges test the speed in the same way that an Edge and a Gateway do on the public link.
- Continuous Path Monitoring: Dynamic Multipath Optimization (DMPO) is a technique that performs continuous, uni-directional measurements of performance metrics. These metrics include loss, delay, and jitter of every packet, on every tunnel, between any two DMPO endpoints, whether they be Edge or Gateway. The per-packet steering feature of VMware SD-WAN enables independent decisions to be made in both the uplink and downlink directions, without introducing any asymmetric routing. A combination of passive and active monitoring strategies is utilized by DMPO. In spite of the fact that there is user traffic, the DMPO tunnel header includes additional performance indicators such as the sequence number and the timestamp. Because of this, the DMPO endpoints are able to determine jitter and latency in each direction, as well as identify lost and out-of-order packets during transmission. Every one hundred milliseconds, the DMPO endpoints exchange information with one another regarding the performance parameters of the path. An active probe is sent every 100 ms when there is no user traffic. After 5 minutes of no high-priority user traffic, the probe frequency drops to 500 ms. This complete measurement lets the DMPO respond very quickly to changes in the underlying WAN state. This means that it can protect against sudden drops in bandwidth capacity and WAN outages in less than a second.
- MPLS Class of Service (CoS): DMPO can be configured to consider CoS when making judgments about application steering and monitoring for a private link that has a CoS agreement.
Dynamic steering of applications
- Application-aware Per-packet Steering: Layer 2 to 7 features, such as VLAN, IP address, protocol, and applications, are used by Dynamic Multipath Optimization (DMPO) to identify traffic. VMware SD-WAN uses real-time network conditions and business policy configuration to execute application-aware per-packet steering. The business policy includes pre-configured Smart Defaults that define the priority and default steering behavior for over 2500 applications: Without defining any policies, users can take advantage of dynamic packet steering and application-aware prioritization right now.
Any traffic flow is directed onto one or more DMPO tunnels at any point during its lifetime, without affecting the flow in any way. An outage condition is when a link is fully unavailable. A link with a brownout situation is one that cannot supply SLA for a certain application. VMware SD-WAN provides protection against abrupt decreases in bandwidth capacity and sub-second outages. By continuously monitoring every WAN connection, DMPO is able to identify sudden SLA loss or outage conditions in less than 300–500 ms. It then promptly redirects traffic flow to safeguard application performance, making sure that it has no negative effects on user experience or active flow. If the business policy specifies it, the DMPO will direct traffic flow back onto the preferred connection after a one-minute hold until the brownout or outage situation on the link is resolved.
By storing classification results, intelligent learning lets the application steer based on the first packet of the application. For example, to send Netflix over the branch Internet link instead of the DMPO tunnel, this is needed for application-based redirection. Office 365 needs to be sent back to the company regional hub or data center.
As an example, Smart Defaults has designated Microsoft Skype for Business as a Real-Time application and a High Priority. That is, if there are two links, each with a latency of 50 ms and 60 ms. Presume that all other SLAs are either met or the same. If a link has a latency of 50 ms or less, DMPO will choose it. If the present link that is used to direct Skype for Business traffic has a high latency of 200 ms, it will redirect the packets to a different link that has a better latency of 60 ms within less than a second.
- Bandwidth Aggregation for Single Flow: DMPO’s per-packet load balancing uses all available links to get all packets in a single flow to their goal. This is useful for applications that could use more bandwidth, like file transfer. When DMPO chooses which paths to use to send the flow’s packets, it looks at how well the WAN is working at the moment. It also resequences packets at the receiving end to make sure that per-packet load balancing doesn’t cause any out-of-order packets to be sent.
Example: For a single traffic flow, two 50 Mbps lines can provide an aggregate capacity of 100 Mbps. Both the aggregate and individual link levels are subject to QoS.
