Huawei NetEngine80E Configuration Manual - Reliability page 54

HUAWEI NetEngine80E/40E Router
Configuration Guide - Reliability
The NE80E/40E currently supports 1:1 bidirectional and 1+1 unidirectional APS working
modes. For more information, see
based on network and application requirements:
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Command-triggered APS switching
Command-triggered APS switching includes protection lock, forcible switching, and manual
switching. Command-triggered APS switching is used during a device upgrade, link
troubleshooting, testing, and maintenance. The three modes are described as follows:
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Delayed Switchback (WTR Time)
After a fault in the working link is rectified, services automatically switch from the protect link
to the working link. During the switchback, some service traffic is dropped because some
resources related to the working link or NE80E/40E are being restored. To prevent service loss,
the WTR time can be set on the NE80E/40E to delay a switchback. Services can automatically
switch from the protect link back to the working link in the specified WTR time after the working
link becomes available.
E-APS Negotiation and Authentication Parameters
Interval between the sent E-APS negotiation messages and E-APS connection hold time
Two E-APS-enabled routers run the Protection Group Protocol (PGP) to exchange control
messages along an outband channel at a specified interval. PGP negotiation messages are
exchanged periodically to verify E-APS connectivity. If no response is received within a
specified period, the router considers its peer router faulty and does not perform E-APS switching
even though a fault occurs or is removed on the working link.
In addition to the interval at which negotiation messages are sent, the E-APS connection hold
time can also be set on the NE80E/40Es. The local NE80E/40E retains the E-APS connection
during the configured hold time. If no negotiation message is received after the hold time expires,
the local NE80E/40E considers the E-APS connection is torn down.
Issue 02 (2014-09-30)
1:1 mode: Only the working link transmits traffic. The protect link takes over traffic only
if the working link fails.
1+1 mode: Both the working and protect links transmit traffic.
Unidirectional mode: If an optical fiber to an interface fails, only the receiver switches its
traffic to the protect link.
Bidirectional mode: If an interface fails, both the sender and the receiver switch their traffic
to the protect link.
Protection lock means that services are transmitted on the working link and will not be
switched to the protect link even though the working link becomes unavailable.
Either forcible or manual APS switching means that services are manually switched from
the working link to the protect link. Their difference is as follows:
– Forcible APS switching takes effect only when the protect link is working properly.
After traffic switches to the protect link, services will be interrupted if a signal degrade
(SD) error occurs on the protect link. Services will switch back to the working link if a
signal failure (SF) occurs on the protect link.
– Manual APS switching can be performed only when both the working and protect links
are working properly. After manual APS switching is performed, services will switch
to the working link if an SF or SD error occurs on the protect link.
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APS Overview. One of the following modes can be configured
3 APS Configuration
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