rapid traffic switching and provides high reliability. However, this mode has a low
channel usage at about 50%.
–
1:1: Two links are set up and only one link works. If the working link works properly,
traffic flows only through the working link. The 1:1 mode allows a high channel usage
but has poorer reliability than the 1+1 mode.
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If a working link fails, APS automatically switches data from a working link to a protect
link, and continues to take effect on data in either of the following modes:
–
Switchback: If the working link recovers, APS switches traffic back to the working link
after the Wait-to-Restore (WTR) timer expires, and allows the protect link to protect
other working links.
–
Non-switchback: If the working link recovers, APS does not switches traffic back to
the working link unless the protect link fails or a switchover request is received.
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If a link fails, either of the following switchovers is performed:
–
Unidirectional switchover: If a working link fails, the sender sends data along both
working and protect links, and the receiver receives data only from the protect link. This
mode is available only when APS works in 1+1 mode.
–
Bidirectional switchover: If a working link fails, the sender sends data only along the
protect link. This mode is available when APS works in either 1:1 or 1+1 node.
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APS provides protection at four levels. The first three levels apply to single-chassis APS
and the fourth applies to E-APS. The four levels are as follows:
–
Interface level: Both a working interface and a protection interface reside on a single
sub-card of a board.
–
Sub-card level: A working interface and a protection interface reside on two sub-cards
of a single board.
–
Board level: A working interface and a protection interface reside on different boards
of a single router.
–
Device level: A working interface and a protection interface are configured on different
routers. A working router is configured with the working interface, and a protect
router is configured with a protection interface. The working and protect routers
exchange control information using the Protect Group Protocol (PGP) over an out-band
management channel.
3.1.2 APS Features Supported by the NE80E/40E
The NE80E/40E supports the Automatic Protection Switching (APS) working modes, enhanced
APS (E-APS) negotiation and authentication parameters, trunk-based APS groups, and
association between an E-APS group and PW redundancy. The APS working modes include
automatic protection switching, command-triggered switching, and delayed switchback with the
wait to restore (WTR) time configured.
The NE80E/40E supports either single-chassis APS or E-APS networking. Working and
protection interfaces must be created for a single-chassis APS or E-APS group. Interfaces on
both ends of a working or protect link must be configured with consistent parameters including
the working or protect link state and automatic APS switching mode.
APS Working Modes
Automatic protection switching
HUAWEI NetEngine80E/40E Router
Configuration Guide - Reliability
3 APS Configuration
Issue 02 (2014-09-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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