![]() In this system, all loop-free alternate paths can be either kept in the EIGRP topology database, or might be used unequally. MPLS may not be needed under these circumstances.Īnother scenario is when Enhanced Interior Gateway Routing Protocol (EIGRP) is built using a mechanism similar to fast reroute, called EIGRP feasible successor (FS). This provides them with sub-50-ms backup paths in the case of failure. For example, they may have protected dense wavelength-division multiplexing (DWDM) to enable automatic protection switching in their transport systems. Service providers may not need MPLS traffic engineering where it will only be used to protect primary paths. ![]() Then if traffic engineering errors occur, LDP can also be used as backup for forwarding traffic. Some topologies might require remote LFA to cover failures - the difference is, you will need to send the traffic to a node that will not send it back, resulting in a microloop.Īlthough you don't need Label Distribution Protocol (LDP) for MPLS traffic engineering, if you are using MPLS for a Layer 2 or Layer 3 VPN, it is better to enable it. Based on the topology, LFA could provide enough fast reroute capability for your primary path, and you wouldn't need MPLS. You can find more information about these concepts in my article, Fast Reroute Mechanisms. Two flavors of IP FRR include loop-free alternate (LFA) and remote LFA. If you already have an IP-enabled network, you may want to consider the IP fast reroute (FRR) feature. In addition, if your equipment doesn't support Open Shortest Path First (OSPF), Intermediate System to Intermediate System (IS-IS), and Resource Reservation Protocol (RSVP), you may need to change hardware or software. Troubleshooting, management, user training, control plane state, and data plane state can all be concerns. If your network is pure IP but not MPLS enabled, bringing many new control plane features into your network might be too complex. Perhaps you are debating whether to use it and in which cases you should consider an alternative. MPLS traffic engineering has been around for more than a decade. ![]() Here I explain the basics of fast reroute and how to use it to create backup and pre-configured paths in MPLS traffic engineering. The most common use for MPLS traffic engineering is fast reroute. These applications are very delay and loss sensitive, so we must ensure that they are adequately supported on the packet-switched network. Voice and video traffic were traditionally carried over circuit-based TDM links. Not all traffic is the same, and not all customers can get the same service. MPLS traffic engineering can be used to meet an SLA. Part 3: Meeting SLAs With MPLS Traffic Routing This article discusses using label-switched paths for bandwidth optimization. These are to optimize bandwidth by selecting an alternate path, to support a service-level agreement (SLA), or to enable fast reroute. MPLS traffic engineering has three major uses. Part 2: MPLS Path Selection For Bandwidth Optimization I discuss how specific traffic paths are defined and calculated using routing attributes and protocols, the design criteria, and other design-centric questions to consider. If you already have MPLS deployed in your network - perhaps for a VPN - MPLS traffic engineering can be very beneficial. Traffic engineering can greatly improve performance in MPLS networks. The new paths can be created manually or via signaling protocols, and they help to speed traffic. This is achieved by adding a short label to each packet with specific routing instructions that direct packets from router to router, rather than allowing the routers to forward them based on next-hop lookups. MPLS allows network engineers to optimize network resources by sending traffic across a less congested physical path, rather than the default shortest path designated by the routing protocol. It has also been adapted for other use cases, and one of the most important is traffic engineering. Multi-Protocol Label Switching (MPLS) was created to improve packet performance in the core of networks, and it is widely used for that purpose. This page provides a wrap-up of my series on MPLS traffic engineering.
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