Dell EMC SmartFabric OS10 User Guide Release 10.5.0

Shortest path first throttling

Use shortest path first (SPF) throttling to delay SPF calculations during periods of network instability. In an OSPF network, a topology change event triggers an SPF calculation that is performed after a start time. When the start timer finishes, a hold time can delay the next SPF calculation for an additional time.

Set the start, hold, and wait timers according to the stability of the OSPF network topology. Enter the values in milliseconds (ms). If you do not specify a start-time, hold-time, or max-wait value, the default values are used.

OSPFv2 and OSPFv3 instances support SPF throttling. By default, SPF timers are disabled in an OSPF instance. Enter the no version of this command to remove the configured SPF timers and disable SPF throttling.

1. Configure an OSPF instance from CONFIGURATION mode, from 1 to 65535.

   router {ospf | ospfv3} instance-number

2. Set OSPF throttling timers in OSPF INSTANCE mode.

   timers spf [start-time [hold-time [max-wait]]]

   • start-time — Configure the initial delay before performing an SPF calculation after a topology change, from 1 to 600000 milliseconds; default 1000.
   • hold-time — Configure the additional delay before performing an SPF calculation when a new topology change occurs, from 1 to 600000 milliseconds; default 10000.
   • max-wait — Configure the maximum amount of hold time that can delay an SPF calculation, from 1 to 600000 milliseconds; default 10000.

Enable SPF throttling (OSPFv2)

OS10(config)# router ospf 100
OS10(config-router-ospf-100)# timers spf 1200 2300 3400

Enable SPF throttling (OSPFv3)

OS10(config)# router ospfv3 10
OS10(config-router-ospf-10)# timers spf 2000 3000 4000

View OSPFv2 SPF throttling

OS10(config-router-ospf-100)# do show ip ospf

Routing Process ospf 100 with ID 12.1.1.1
Supports only single TOS (TOS0) routes
It is Flooding according to RFC 2328
SPF schedule delay 1200 msecs, Hold time between two SPFs 2300 msecs
Convergence Level 0
Min LSA origination 0 msec, Min LSA arrival 1000 msec
Min LSA hold time 5000 msec, Max LSA wait time 5000 msec
Number of area in this router is 1, normal 1 stub 0 nssa 0
Area (0.0.0.1)
Number of interface in this area is 1
SPF algorithm executed 1 times

View OSPFv3 SPF throttling

OS10(config-router-ospfv3-100)# timers spf 1345 2324 9234

OS10(config-router-ospfv3-100)# do show ipv6 ospf
Routing Process ospfv3 100 with ID 129.240.244.107
SPF schedule delay 1345 msecs, Hold time between two SPFs 2324 msecs
Min LSA origination 5000 msec, Min LSA arrival 1000 msec
Min LSA hold time 0 msec, Max LSA wait time 0 msec
Number of area in this router is 1, normal 1 stub 0 nssa
Area (0.0.0.1)
Number of interface in this area is 1
SPF algorithm executed 2 times