Describes the configuration process of MPLS fast re-routing technology

At present, the MPLS fast rerunning technology is widely used. We believe that with the development of the communication industry, the MPLS fast rerunning technology will be more comprehensive and stable, bringing users a good network environment. To meet real-time applications such as video conferencing and television services, LSP protection capabilities similar to traditional SDHAPS must be provided for these traffic in milliseconds.

The LSP Protection Switching technology requires the involvement of the signaling protocol. The failure indicator signaling transmission from the fault point to the recovery point introduces unnecessary network recovery latency. MPLS fast rerunning technology enables the fault detection point to redirect the traffic of the faulty link based on the preset protection path without signaling intervention. The recovery point is the fault point. Most of the fast rerunning solutions rely on pre-established backup channels. When a network recovery point detects a network failure, it must update the LSP exchange table simply, switch traffic from the LSP of the faulty port to the LSP established on the normal port in advance.

In addition to improving the speed of protection and recovery, the advantage of fast rerunning can avoid repeated protection in reliable networks and unnecessary consumption of core network resources by configuring protection capabilities in poor network links. MPLS fast re-routing technology provides protection switching within 50 ms and can be used as an alternative to SDHAPS protection mechanism.

The MPLS fast rerunning technology adopts the following configuration process:

First, at the entrance of LSP, LSR1, use a USER command to activate the MPLS fast re-routing technology to protect the switching function. LSR1 sends signals to all LSR In the LSP path, each LSR calculates a backup lsp for the next lsr bypass, and the LSP fast rerunning configuration is complete. When an LSR In the LSP path detects a downstream fault, the LSR switches the traffic locally to the backup LSP. IETF has a variety of fast and rerouting solutions. The two mainstream protection methods are Link Protection and node protection. They have different ideas and complexity for solving problems, at present, this technology has not yet formed a formal RFC.

Stable restart of Gracefulrestart)

Possible causes of control plane restart include software upgrade, software Bug, or hardware failure. When the control plane is restarted without interruption, the data plane is forwarded without interruption. However, if the control plane fails, the peer router will re-calculate the route, bypass the faulty router, and the data plane's uninterrupted forwarding will be meaningless, and the faulty route will spread throughout the network. In MPLS fast rerunning technology, if this happens, the result is disastrous.

The control plane stable restart technology can effectively solve this problem. When the control plane fails, the router using this technology can notify the neighboring router to continue using the original path for data forwarding, at the same time, restart the router to reconnect with the neighboring router to establish the Routing Status, ensure service availability during the restart process, and minimize the impact of the restart of a single device on the entire network. During the smooth restart process, the router does not save the relevant protocol status, so the software failure caused by the restart will not continue until after the restart. Stable restart is a new feature and is not supported by many old devices. Therefore, it can be used on devices that support this feature in a local subnet.

In terms of network boundaries, carrier vbrs face numerous customers and generally do not have redundancy measures. Therefore, it is best to use the stable Restart Technology. The network core usually uses redundant paths for protection, and service restart may easily cause routing loops. Therefore, it is not recommended to use stable Restart Technology on the network core.