OS10 Enterprise Edition User Guide Release 10.4.1.0

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Fast convergence

Fast convergence sets the minimum origination and arrival LSA parameters to zero (0), allowing rapid route calculation. A higher convergence level can result in occasional loss of OSPF adjacency.

Convergence level 1 meets most convergence requirements. The higher the number, the faster the convergence, and the more frequent the route calculations and updates. This impacts CPU utilization and may impact adjacency stability in larger topologies.

  • NOTE: Select the higher convergence levels only after checking with Dell Technical Support.

When you disable fast-convergence, origination and arrival LSA parameters are set to 0 msec and 1000 msec, respectively. Setting the convergence parameter from 1 to 4 indicates the actual convergence level. Each convergence setting adjusts the LSA parameters to zero, but the convergence-level parameter changes the convergence speed. The higher the number, the faster the convergence.

  • Enable OSPFv2 fast-convergence and enter the convergence level in ROUTER-OSPF mode from 1 to 4.
    fast-converge 
                                           convergence-level
                                        

Configure fast convergence

OS10(config)# router ospf 65535
                                 OS10(conf-router-ospf-65535)# fast-converge 1
                              

View fast convergence

OS10(conf-router-ospf-65535)# do show ip ospf
                                 
                                 Routing Process ospf 65535 with ID 99.99.99.99
                                 Supports only single TOS (TOS0) routes
                                 It is an Autonomous System Border Router
                                 It is an Area Border Router
                                 It is Flooding according to RFC 2328
                                 Convergence Level 1
                                 Min LSA origination 0 msec, Min LSA arrival 0 msec
                                 Min LSA hold time 0 msec, Max LSA wait time 0 msec
                                 Number of area in this router is 3, normal 1 stub 1 nssa 1
                                 Area BACKBONE (0)
                                 Number of interface in this area is 1
                                 SPF algorithm executed 28 times
                                 Area ranges are
                                 
                                 Area  (2)
                                 Number of interface in this area is 1
                                 SPF algorithm executed 28 times
                                 Area ranges are
                                 
                                 Area  (3)
                                 Number of interface in this area is 1
                                 SPF algorithm executed 28 times
                                 Area ranges are
                              

Disable fast convergence

OS10(conf-router-ospf-65535)# no fast-converge

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