MPLS Traffic Engineering

Total 2 Blogs

Created by - Orhan Ergun


RSVP-TE vs. SR-TE RSVP-TE (Resource Reservation Protocol-Traffic Engineering) and SR-TE (Segment Routing Traffic Engineering) are two different approaches to traffic engineering in IP networks. RSVP-TE is a protocol that enables the reservation of network resources, such as bandwidth, for specific traffic flows. It works by establishing a path between the source and destination nodes of a flow, and then reserving resources along that path. RSVP-TE is widely used in traditional MPLS networks, where the control plane is separate from the forwarding plane. SR-TE, on the other hand, is a newer approach to traffic engineering that uses a different paradigm called "source routing." In SR-TE, the source node of a traffic flow specifies the path that the flow should take through the network. The network nodes along the path simply forward the traffic based on the instructions provided by the source node. This approach simplifies the control plane, as the path selection and resource reservation are handled by the source node rather than the network. Both RSVP-TE and SR-TE have their own strengths and weaknesses, and the choice between them depends on the specific needs of the network and the applications running on it. RSVP-TE and SR-TE are two different technologies used in Multiprotocol Label Switching (MPLS) networks to establish label-switched paths (LSPs). RSVP-TE (Resource Reservation Protocol-Traffic Engineering) is a signaling protocol used to establish LSPs in MPLS networks. RSVP-TE works by setting up a signaling path between the ingress and egress routers, which reserves network resources along the path. This allows for traffic engineering, which involves controlling the flow of traffic to optimize network performance and efficiency. Segment Routing Traffic Engineering (SR-TE), on the other hand, is a newer technology that allows for traffic engineering in MPLS networks using a simplified approach. Instead of using signaling protocols like RSVP-TE to establish LSPs, SR-TE uses a routing protocol to define the path that a packet should take through the network. This path is determined by the use of a segment list, which is a list of labels that define the path that the packet should take through the network. In general, SR-TE is considered to be a more scalable and flexible solution for traffic engineering in MPLS networks, as it simplifies the process of establishing LSPs and reduces the amount of signaling required. However, RSVP-TE is still widely used and may be preferred in certain situations where more fine-grained control is required over the traffic engineering process.

Published - Wed, 22 Mar 2023

Created by - Orhan Ergun

What is MP – Merge Point in MPLS Traffic Engineering ?

What is MP, Merge Point in MPLS Traffic Engineering ? Understanding Merge Point in MPLS Traffic Engineering will help you to understand the MPLS TE – Fast Reroute.   MP (Merge Point) is the term is used in the context of Fast Reroute. I briefly mentioned from Merge Point in the MPLS Traffic Engineering Fast Reroute Link Protection post earlier and in this post, will explain it in more detail.   Let’s look at the below topology.Figure - Merge Point in MPLS Traffic Engineering MPLS TE FRR Link Protection     As it is depicted in the topology as well, red is primary LSP , which means working path, so it carries the traffic.   Green is the backup LSP and it is just standby and incase of failure it will be used. With MPLS Traffic Engineering Fast Reroute, link and node failure can be protected. This picture shows us the link failure, because M- N link failure is protected (Traffic will be redirected immediately in case M-N link fails)   Link between Router M and N. If that link fails, network traffic can not be carried between A and D through red LSP, which is the primary path.   It will be broken between Router M and N. But if the requirement is to continue carrying traffic over an alternate path within 50 msec, fast reroute is used. If the traffic flow from router A to D, in case Router M to N link failures, who can send the traffic towards green LSP ?   Router M right ? Because, Router M will learn first about the link failure when Router M – N link fails.    Router M as it is directly attached to the failed link , redirect the traffic to the green LSP. Both primary LSP and Green LSP is terminated on the node N.   In case M-N link fails, if traffic reaches again to the node N, node N can continue forward the traffic to the destination which is Router D.   Node N is called a Merge Point (MP), because backup LSP is merged to the primary LSP at that router/node.

Published - Tue, 26 Nov 2019