Paragon Planner Fast Reroute Overview
This topic and related topics describe how to design Fast Reroute (FRR) backup tunnels. Fast Reroute is a mechanism that can be used to protect MPLS traffic engineering LSP tunnels in the event of node or link failures. It accomplishes this with SONET-like restoration times by locally repairing the LSPs at the point of failure, using backup tunnels that bypass the failure while waiting for the head-end routers to establish a new LSP. The short restoration times are especially desirable for real-time applications such as voice over IP, which often cannot tolerate high delays.
Paragon Planner supports simulation and design of both FRR Node Protection and FRR Link Protection. When a tunnel that has requested FRR protection fails at a particular network element and when there is a FRR backup tunnel configured for that node or link, the packets can be diverted along the backup tunnel until the original tunnel is able to reroute around the failed network element.
Use the Paragon Planner Fast Reroute features to view or modify FRR configurations, to design FRR backup tunnels for your network, and to generate configlets for primary and backup tunnels where applicable. You should also use this feature to simulate and analyze the impact or effectiveness of your FRR backup tunnels on the network in the event of network element failures.
You should have LSP tunnels defined in your network model.
If you want your FRR backup tunnels to be routed over site-diverse or facility-diverse (SRLG) paths, you should first create sites and facilities on your network.
Graphical Display
Paragon Planner can be used to import existing tunnel path information collected through show commands and to graphically display all the FRR backup tunnel paths protecting the links or nodes of a primary tunnel, and all the primary tunnels being protected by a given FRR backup tunnel.
What-If Studies and Path Design
Users can perform what-if studies by configuring primary tunnels to request FRR protection, and then allow Paragon Planner to design the FRR backup tunnels. Paragon Planner can be used to simulate the creation of backup tunnels in the case where it is automatically generated for what-if studies, or to help design diverse backup tunnels in the case where the user wants to configure the backup tunnels to meet particular diversity requirements. Consequently, LSP configlets can be generated to facilitate the process of updating the routers.
Failure Simulation
Furthermore, Paragon Planner can also be used to perform failure analysis, showing whether the demands are successfully protected through FRR during node or link failure, and then indicating the rerouted path onto the backup path, if configured, whether it be secondary (passive) or standby (active/1+1). Users can view the peak utilization when using FRR.
For instructions on how to view or modify the tunnels in your network, see Paragon Planner LSP Tunnels Overview.