Reference Guide

Shortest path rst throttling
Use shortest path rst (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 nishes, a hold time can delay the next
SPF calculation for an additional time.
When the hold timer is running:
• Each time a topology change occurs, the SPF calculation is delayed for double the congured hold time up to maximum wait time.
• If no topology change occurs, an SPF calculation is performed and the hold timer is reset to its congured value.
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 congured SPF timers and disable SPF throttling.
1 Congure an OSPF instance from CONFIGURATION mode (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 — Congure the initial delay before performing an SPF calculation after a topology change (1 to 600000
milliseconds; default 1000).
• hold-time — Congure the additional delay before performing an SPF calculation when a new topology change occurs (1 to
600000 milliseconds; default 10000).
• max-wait — Congure the maximum amount of hold time that can delay an SPF calculation (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
Layer 3
347