In last week’s blog, we explained that a Segment Routing (SR) path is an ordered list of segments. We also explained that a segment is an instruction that causes a packet to traverse one or more links.
This week, we will discuss a class of SR implementations that leverage MPLS. We refer to these implementations as SR-MPLS. A thorough understanding of SR-MPLS will help you understand next week’s blog, in which we explain how SR supports traffic engineering applications.
In last week’s blog, we introduced Segment Routing (SR) as an innovative traffic steering mechanism. We also introduced SR domains, policies, paths and segments. This week, we will explore them further.
The Internet was initially designed to provide best-effort connectivity over a least-cost path. Relatively few sites were connected to the Internet, and within those sites, only applications that satisfied an acceptable use policy could be connected.
Today, billions of businesses, households and devices are connected to the Internet. Critical applications include telemedicine, traffic control and financial transactions. Some applications (e.g., email) are tolerant of loss, latency and latency variation, while other applications (e.g., gaming) are significantly less tolerant.
In a medical emergency, every second counts. The more paramedics can do on the scene, the better it is for the patient. A more stable patient also means less need to race through traffic or for emergency handovers at the hospital, all of which impact the chance of a successful outcome.
At the Open Compute Project (OCP) Global Summit in San Jose, CA earlier this month Juniper further demonstrated its commitment to open programmability with integrations with Software for Open Networking in the Cloud (SONiC) and Switch Abstraction Interface (SAI) on Juniper single and multi-PFE platforms.
Designing a network that provides optimal SLAs for its applications – bandwidth & latency guarantees, uptime and responsiveness - while reducing costs is a classic networking challenge. Historically, network planners have used sophisticated tools such as WANDL’s IP/MPLS View for capacity and scenario planning. Similarly, leading routing vendors have delivered real time end-to-end traffic engineering with built in CSPF (Constrained Shortest Path First) algorithms and RSVP-TE. These technologies have driven the growth of Internet and cloud applications by ensuring that cloud applications achieve desired network SLAs.
However, as cloud traffic continues to surge and new cloud services continue to go viral, network architectures must become simpler and more modular. New network architectures must allow more service customization and agility, while utilizing more cost effective routers/switches to transport ever increasing traffic economically. Most critically, network architectures must simplify operations.
Segment Routing (IETF name: SPRING) delivers network simplification by eliminating MPLS signaling protocols such as LDP and RSVP. It eliminates the hop-by-hop LSP path setup paradigm and allows the head-end router (or an application) to define the entire path for the application traffic by encoding path information in the packet itself. In this new SR paradigm, since the network contains no traffic engineering (TE) information, a Segment Routing (SR) controller is a must in order to ensure real time, end-to-end application level TE and SLA guarantees.