Cisco ASR-920-4SZ-D User Manual

G.8032 ERP Timers
The G.8032 Ethernet Ring Protection (ERP) protocol specifies the use of different timers to avoid race
conditions and unnecessary switching operations:
• Delay timers—Used by the Ring Protection Link (RPL) owner to verify that the network has stabilized
before blocking the RPL. Note the following points about delay timers.
•
After a signal failure (SF) condition, a Wait-to-Restore (WTR) timer is used to verify that the SF
is not intermittent.
•
The WTR timer can be configured by the operator. The default time interval is 5 minutes; the time
interval ranges from 1 to 12 minutes.
•
After a force switch (FS) or a manual switch (MS) command is issued, a Wait-to-Block (WTB)
timer is used to verify that no background condition exists.
The WTB timer interval may be shorter than the WTR timer interval.Note
• Guard timer—Used by all nodes when changing state; the guard timer blocks latent outdated messages
from causing unnecessary state changes. The guard timer can be configured. The default time interval
is 500 ms; the time interval ranges from 10 to 2000 ms.
• Hold-off timers—Used by the underlying Ethernet layer to filter out intermittent link faults. The hold-off
timer can be configured. The default time interval is 0 seconds; the time interval ranges from 0 to 10
seconds. Faults are reported to the ring protection mechanism only if this timer expires.
LAN Switching Configuration Guide Cisco IOS XE Everest 16.5.1 (Cisco ASR 900 Series)
50
ITU-T G.8032 Ethernet Ring Protection Switching
G.8032 ERP Timers

Cisco ASR-920-4SZ-D Specifications

General

Brand	Cisco
Model	ASR-920-4SZ-D
Category	Network Router
Language	English