Part 1: Two-Way Active Measurement Protocol (TWAMP)
In this series of blogs, we delve into the details of performance measurement and network assurance for service providers. In the first part we shall explore the TWAMP solution.
In the fast-paced world of telecommunications, service providers are the backbone of connectivity, enabling businesses and individuals to stay linked across the globe. From delivering point-to-point connections for dedicated bandwidth to managing multipoint services that interconnect multiple locations, and facilitating seamless connections to gateway services for broader internet or cloud access, their networks must operate with exceptional precision and reliability.
To meet these demands, service providers need more than just robust infrastructure—they require a strategic focus on performance measurement and network assurance. These practices ensure their networks deliver on service-level agreements (SLAs), maintain reliability, and provide the consistent quality of experience (QoE) that customers expect.
Two Way Measurement Protocol (TWAMP) is a standardized protocol defined by the IETF IP Performance Measurement (IPPM) working group in RFC 5357 and is an extension of the OWAMP (One-Way Active Measurement Protocol). TWAMP provides round-trip delay, packet loss, jitter, and other performance metrics, making it highly useful for monitoring and troubleshooting network performance.
TWAMP has two major roles:
- Control Plane (TWAMP-Control): Sets up and manages the test sessions.
- Measurement Plane (TWAMP-Test): Handles the actual performance measurement by exchanging test packets.
These roles are performed using specific components:
- Control Client: Initiates and manages TWAMP sessions.
- Control Server: Accepts and establishes TWAMP sessions.
- Session-Sender: Sends test packets to the remote endpoint.
- Session-Reflector: Receives test packets and sends responses.
Session Setup is done in the Control-plane where Control-Client initiates sessions by connecting to the Control-Server over TCP (default port 862). The client and server negotiate session parameters such as:
- Number of test packets
- Test duration
- Authentication method (none, authentication or encryption)
The Session-Sender sends test packets over UDP on the negotiated port to the Session-Reflector. The Session-Reflector immediately responds to each received packet. Both ends timestamp the packets upon sending and receiving. With the help of this packet exchange Session-Sender calculates the Round-trip-delay, Packet-loss and Jitter.
Control-Client closes the session once testing is complete.
One might think, before TWAMP we had ICMP and BFD to do some primary L3 tests so why have they not been used/enhanced in IP performance measurement? The purposes are different, and the following comparison provides some details on this.
Following is a sample output of a TWAMP session with PTP synced between both the nodes:
In summary TWAMP becomes a key part of Network Assurance and helps service providers to gain more confidence from their customers and hence brings in more business.
In the upcoming articles we shall continue to explore other network monitoring and measurement techniques including Y.1731, Y.1564, sFlow and Streaming Telemetry.
In OcNOS, TWAMP is supported for regular L3, L3VPN over MPLS/SR transport and EVPN-L3VPN over MPLS/SR transport. For more details refer to OcNOS Feature Matrix and Config Guides.
Contact us to explore OcNOS solutions for Service Providers.
Prasanna Kumara S is a Technical Marketing Engineer for IP Infusion.