Huawei AR530 Series User manual

Huawei AR530&AR550 Series Industrial Switch
Routers
V200R005C70
Configuration Guide - Reliability
Issue 01
Date 2014-11-30
HUAWEI TECHNOLOGIES CO., LTD.

Copyright © Huawei Technologies Co., Ltd. 2015. All rights reserved.
No part of this document may be reproduced or transmitted in any form or by any means without prior written
consent of Huawei Technologies Co., Ltd.
Trademarks and Permissions
and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd.
All other trademarks and trade names mentioned in this document are the property of their respective holders.
Notice
The purchased products, services and features are stipulated by the contract made between Huawei and the
customer. All or part of the products, services and features described in this document may not be within the
purchase scope or the usage scope. Unless otherwise specified in the contract, all statements, information,
and recommendations in this document are provided "AS IS" without warranties, guarantees or representations
of any kind, either express or implied.
The information in this document is subject to change without notice. Every effort has been made in the
preparation of this document to ensure accuracy of the contents, but all statements, information, and
recommendations in this document do not constitute a warranty of any kind, express or implied.
Huawei Technologies Co., Ltd.
Address: Huawei Industrial Base
Bantian, Longgang
Shenzhen 518129
People's Republic of China
Website: http://enterprise.huawei.com
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About This Document
Intended Audience
This document provides the basic concepts, configuration procedures, and configuration
examples of the reliability supported by the device.
This document is intended for:
lData configuration engineers
lCommissioning engineers
lNetwork monitoring engineers
lSystem maintenance engineers
Symbol Conventions
The symbols that may be found in this document are defined as follows.
Symbol Description
Indicates an imminently hazardous situation
which, if not avoided, will result in death or
serious injury.
Indicates a potentially hazardous situation
which, if not avoided, could result in death or
serious injury.
Indicates a potentially hazardous situation
which, if not avoided, may result in minor or
moderate injury.
Indicates a potentially hazardous situation
which, if not avoided, could result in
equipment damage, data loss, performance
deterioration, or unanticipated results.
NOTICE is used to address practices not
related to personal injury.
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Symbol Description
NOTE
Calls attention to important information, best
practices and tips.
NOTE is used to address information not
related to personal injury, equipment damage,
and environment deterioration.
Command Conventions
The command conventions that may be found in this document are defined as follows.
Convention Description
Boldface The keywords of a command line are in boldface.
Italic Command arguments are in italics.
[ ] Items (keywords or arguments) in brackets [ ] are optional.
{ x | y | ... } Optional items are grouped in braces and separated by
vertical bars. One item is selected.
[ x | y | ... ] Optional items are grouped in brackets and separated by
vertical bars. One item is selected or no item is selected.
{ x | y | ... }*Optional items are grouped in braces and separated by
vertical bars. A minimum of one item or a maximum of all
items can be selected.
[ x | y | ... ]*Optional items are grouped in brackets and separated by
vertical bars. Several items or no item can be selected.
&<1-n> The parameter before the & sign can be repeated 1 to n times.
# A line starting with the # sign is comments.
Interface Numbering Conventions
Interface numbers used in this manual are examples. In device configuration, use the existing
interface numbers on devices.
Security Conventions
lPassword setting
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–When configuring a password, the cipher text is recommended. To ensure device
security, change the password periodically.
–When you configure a password in plain text that starts and ends with %@%@ (the
password can be decrypted by the device), the password is displayed in the same manner
as the configured one in the configuration file. Do not use this setting.
–When you configure a password in cipher text, different features cannot use the same
cipher-text password. For example, the cipher-text password set for the AAA feature
cannot be used for other features.
lEncryption algorithm
Currently, the device uses the following encryption algorithms: 3DES, AES, RSA, SHA1,
SHA2, and MD5. 3DES, RSA and AES are reversible, while SHA1, SHA2, and MD5 are
irreversible. The encryption algorithms DES/3DES/RSA (RSA-1024 or lower)/MD5 (in
digital signature scenarios and password encryption)/SHA1 (in digital signature scenarios)
have a low security, which may bring security risks. If protocols allowed, using more secure
encryption algorithms, such as AES/RSA (RSA-2048 or higher)/SHA2/HMAC-SHA2, is
recommended. The encryption algorithm depends on actual networking. The irreversible
encryption algorithm must be used for the administrator password, SHA2 is recommended.
lPersonal data
Some personal data may be obtained or used during operation or fault location of your
purchased products, services, features, so you have an obligation to make privacy policies
and take measures according to the applicable law of the country to protect personal data.
lThe terms mirrored port, port mirroring, traffic mirroring, and mirroing in this manual are
mentioned only to describe the product's function of communication error or failure
detection, and do not involve collection or processing of any personal information or
communication data of users.
Change History
Changes between document issues are cumulative. Therefore, the latest document version
contains all updates made to previous versions.
Changes in Issue 01 (2014-11-30)
Initial commercial release.
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Contents
About This Document.....................................................................................................................ii
1 Introduction to Reliability...........................................................................................................1
1.1 Levels of Reliability Requirements................................................................................................................................2
1.2 Reliability Specifications................................................................................................................................................2
1.3 Reliability Technologies.................................................................................................................................................3
2 Interface Backup Configuration.................................................................................................5
2.1 Introduction to Interface Backup....................................................................................................................................6
2.2 Principles........................................................................................................................................................................6
2.2.1 Interface Backup in Active/Standby Mode..................................................................................................................6
2.2.2 Load Balancing Mode.................................................................................................................................................7
2.3 Applications....................................................................................................................................................................7
2.3.1 Interface Backup in Active/Standby Mode..................................................................................................................7
2.3.2 Interface Backup in Load Balancing Mode.................................................................................................................8
2.3.3 Association Between Interface Backup in Active/Standby Mode and NQA..............................................................8
2.3.4 Association Between Interface Backup in Active/Standby Mode and BFD...............................................................9
2.3.5 Association Between Interface Backup in Active/Standby Mode and Routing........................................................10
2.4 Configuration Task Summary......................................................................................................................................11
2.5 Default Configuration...................................................................................................................................................12
2.6 Interface Backup Configuration...................................................................................................................................13
2.6.1 Configuring Interface Backup in Active/Standby Mode...........................................................................................13
2.6.2 Configuring Association of Interface Backup in Active/Standby Mode...................................................................14
2.6.2.1 Configuring Association Between Interface Backup in Active/Standby Mode and NQA.....................................14
2.6.2.2 Configuring Association Between Interface Backup in Active/Standby Mode and BFD......................................15
2.6.2.3 Configuring Association Between Interface Backup in Active/Standby Mode and Routing................................17
2.6.3 Configuring Interface Backup in Load Balancing Mode..........................................................................................18
2.7 Configuration Examples...............................................................................................................................................20
2.7.1 Example for Configuring Ethernet Interface Backup in Active/Standby Mode........................................................20
2.7.2 Example for Configuring Ethernet Interface Backup in Load Balancing Mode.......................................................23
2.7.3 Example for Configuring an ADSL Interface as the Backup of an Ethernet Interface ............................................26
2.7.4 Example for Configuring Association Between NQA and Ethernet Interface Backup in Active/Standby Mode
............................................................................................................................................................................................29
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2.7.5 Example for Configuring Association Between BFD and Ethernet Interface Backup in Active/Standby Mode
............................................................................................................................................................................................35
2.7.6 Example for Configuring Association Between Routing and Ethernet Interface Backup in Active/Standby Mode
............................................................................................................................................................................................40
2.7.7 Example for Associating Interface Backup with NQA to Configure an ADSL Interface as the Backup of an Ethernet
Interface..............................................................................................................................................................................46
2.7.8 Example for Associating Interface Backup with BFD to Configure an ADSL Interface as the Backup of an Ethernet
Interface..............................................................................................................................................................................52
2.7.9 Example for Associating Interface Backup with Routing to Configure an ADSL Interface as the Backup of an Ethernet
Interface..............................................................................................................................................................................59
2.8 References....................................................................................................................................................................65
3 Interface Monitoring Group Configuration...........................................................................66
3.1 Introduction..................................................................................................................................................................67
3.2 Interface Monitoring Group Principles.........................................................................................................................67
3.3 Interface Monitoring Group Application......................................................................................................................68
3.4 Configuring an Interface Monitoring Group................................................................................................................69
3.5 Maintaining an Interface Monitoring Group................................................................................................................71
3.5.1 Shutting Down an Interface Monitoring Group........................................................................................................71
3.5.2 Deleting Invalid Interfaces from an Interface Monitoring Group.............................................................................71
3.6 Example for Configuring an Interface Monitoring Group...........................................................................................72
4 HSB Configuration......................................................................................................................77
4.1 Introduction to Hot-Standby Backup............................................................................................................................79
4.2 Principles......................................................................................................................................................................79
4.2.1 Backup Modes...........................................................................................................................................................79
4.2.2 HSB Implementation.................................................................................................................................................80
4.3 Applications..................................................................................................................................................................82
4.3.1 Using HSB to Improve Firewall Reliability..............................................................................................................82
4.4 Default Configuration...................................................................................................................................................83
4.5 HSB Configuration.......................................................................................................................................................84
4.5.1 Configure a VRRP group..........................................................................................................................................84
4.5.2 Creating an HSB Service...........................................................................................................................................85
4.5.3 Configuring an HSB Group.......................................................................................................................................86
4.5.4 Enabling an HSB Group............................................................................................................................................87
4.5.5 Checking the Configuration.......................................................................................................................................87
4.6 Configuration Examples...............................................................................................................................................88
4.6.1 Example for Configuring HSB..................................................................................................................................88
4.7 Common Configuration Errors.....................................................................................................................................93
4.7.1 Information on the Master Device Fails to Be Backed up to the Backup Device.....................................................93
4.8 References....................................................................................................................................................................94
5 BFD Configuration......................................................................................................................95
5.1 Introduction to BFD......................................................................................................................................................96
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5.2 Principles......................................................................................................................................................................96
5.3 Application Scenarios...................................................................................................................................................99
5.3.1 BFD for IP Links.......................................................................................................................................................99
5.3.2 BFD Echo Function.................................................................................................................................................100
5.3.3 Association Between the BFD Session Status and the Interface Status..................................................................100
5.3.4 BFD for Static Routes..............................................................................................................................................101
5.3.5 BFD for OSPF.........................................................................................................................................................101
5.3.6 BFD for IS-IS..........................................................................................................................................................102
5.3.7 BFD for BGP...........................................................................................................................................................103
5.3.8 BFD for VRRP........................................................................................................................................................104
5.3.9 BFD for PIM............................................................................................................................................................105
5.4 Configuration Task Summary....................................................................................................................................106
5.5 Default Configuration.................................................................................................................................................107
5.6 Configuring BFD........................................................................................................................................................107
5.6.1 Configuring Single-Hop BFD.................................................................................................................................107
5.6.2 Configuring Multi-Hop BFD...................................................................................................................................110
5.6.3 Configuring Static BFD with Automatically Negotiated Discriminators...............................................................111
5.6.4 Configuring the BFD Echo Function.......................................................................................................................112
5.6.5 Configuring BFD Association.................................................................................................................................114
5.6.5.1 Configuring Association Between the BFD Session and the Interface Status.....................................................114
5.6.5.2 Configuring Association Between the BFD Session Status and the Sub-interface Status...................................117
5.6.6 Adjusting BFD Parameters......................................................................................................................................119
5.6.6.1 Adjusting the BFD Detection Time......................................................................................................................119
5.6.6.2 Setting the WTR Time of a BFD Session.............................................................................................................120
5.6.6.3 Configuring the Description for a BFD Session...................................................................................................121
5.6.6.4 Setting the Delay Before a BFD Session Becomes Up........................................................................................121
5.6.6.5 Setting the Global TTL Value..............................................................................................................................122
5.6.7 Checking the Configuration.....................................................................................................................................123
5.7 Clearing BFD Session Statistics.................................................................................................................................123
5.8 Configuration Examples.............................................................................................................................................124
5.8.1 Example for Configuring Single-hop BFD for Detecting Faults on a Layer 2 Link...............................................124
5.8.2 Example for Configuring Single-Hop BFD on a VLANIF Interface......................................................................126
5.8.3 Example for Configuring single-hop BFD on a Layer 3 Physical Link..................................................................129
5.8.4 Example for Configuring Multi-Hop BFD..............................................................................................................131
5.8.5 Example for Associating the BFD Session Status with the Interface Status...........................................................134
5.8.6 Example for Configuring BFD on a Dot1q Termination Sub-interface..................................................................139
5.8.7 Example for Configuring the BFD Echo Function..................................................................................................145
5.9 Common Configuration Errors...................................................................................................................................147
5.9.1 BFD Session Cannot Become Up............................................................................................................................147
5.9.2 BFD Detection Result Affects Forwarding on an Interface....................................................................................148
5.9.3 Modified BFD Parameters Do Not Take Effect......................................................................................................148
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5.10 References................................................................................................................................................................149
6 VRRP Configuration.................................................................................................................150
6.1 Introduction to VRRP.................................................................................................................................................152
6.2 Principles....................................................................................................................................................................152
6.2.1 Basic Concepts of VRRP.........................................................................................................................................152
6.2.2 VRRPv2 and VRRPv3 Advertisement Packets.......................................................................................................154
6.2.3 VRRP Implementation............................................................................................................................................157
6.2.4 VRRP in Active/Standby Mode..............................................................................................................................160
6.2.5 VRRP in Load Balancing Mode..............................................................................................................................161
6.3 Applicable Scenarios..................................................................................................................................................162
6.3.1 Association Between a VRRP Group and the Interface Status to Monitor the Uplink Interface............................162
6.3.2 Association Between VRRP and BFD/NQA/Routing to Monitor the Uplink........................................................163
6.3.3 Association Between VRRP and BFD to Implement a Rapid Active/Standby Switchover...................................164
6.3.4 Configuring Layer 2 and Layer 3 Traffic Load Balancing Through VRRP and MSTP Deployment.....................166
6.4 Configuration Task Summary....................................................................................................................................167
6.5 Configuration Notes...................................................................................................................................................169
6.6 Default Configuration.................................................................................................................................................170
6.7 Configuring VRRP.....................................................................................................................................................170
6.7.1 Configuring Basic Functions of an IPv4 VRRP Group...........................................................................................170
6.7.1.1 Creating a VRRP Group.......................................................................................................................................170
6.7.1.2 Setting the Device Priority in a VRRP Group......................................................................................................171
6.7.1.3 (Optional) Configuring the VRRP Version Number............................................................................................172
6.7.1.4 (Optional) Configuring VRRP Time Parameters.................................................................................................172
6.7.1.5 (Optional) Setting the Mode in Which VRRP Advertisement Packets Are Sent in a Super-VLAN...................175
6.7.1.6 (Optional) Disabling VRRP TTL Check..............................................................................................................176
6.7.1.7 (Optional) Setting the Authentication Mode of VRRP Advertisement Packets...................................................176
6.7.1.8 (Optional) Enabling the Ping to a Virtual IP Address..........................................................................................177
6.7.1.9 Checking the Configuration..................................................................................................................................178
6.7.2 Configuring VRRP Association..............................................................................................................................179
6.7.2.1 Configuring Association Between VRRP and BFD to Implement a Rapid Active/Standby Switchover............179
6.7.2.2 Configuring Association Between VRRP and the Interface Status to Implement an Active/Standby Switchover
..........................................................................................................................................................................................181
6.7.2.3 Configuring Association Between VRRP and BFD to Monitor the Uplink Status..............................................181
6.7.2.4 Configuring Association Between VRRP and NQA to Monitor the Uplink Status.............................................183
6.7.2.5 Configuring Association Between VRRP and Routing to Monitor the Uplink Status.........................................184
6.7.2.6 Checking the Configuration..................................................................................................................................185
6.7.3 Configuring Basic Functions of an IPv6 VRRP Group...........................................................................................185
6.7.3.1 Creating a VRRP6 Group.....................................................................................................................................185
6.7.3.2 Setting the Device Priority in a VRRP6 Group....................................................................................................187
6.7.3.3 (Optional) Configuring VRRP6 Time Parameters...............................................................................................187
6.7.3.4 (Optional) Disabling VRRP6 TTL Check............................................................................................................190
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6.7.3.5 (Optional) Enabling the Ping to a Virtual IP Address..........................................................................................191
6.7.3.6 Checking the Configuration..................................................................................................................................191
6.7.4 Configuring VRRP6 Association............................................................................................................................192
6.7.4.1 Configuring Association Between VRRP6 and the Interface Status to Implement an Active/Standby Switchover
..........................................................................................................................................................................................192
6.7.4.2 Checking the Configuration..................................................................................................................................193
6.8 Maintaining VRRP.....................................................................................................................................................193
6.8.1 Monitoring the VRRP Running Status....................................................................................................................193
6.8.2 Clearing VRRP Advertisement Packet Statistics....................................................................................................193
6.9 Configuration Examples.............................................................................................................................................194
6.9.1 Example for Configuring a VRRP Group in Active/Standby Mode.......................................................................194
6.9.2 Example for Configuring a VRRP Group in Multi-gateway Load Balancing Mode..............................................198
6.9.3 Example for Configuring Association Between VRRP and BFD to Implement a Rapid Active/Standby Switchover
..........................................................................................................................................................................................202
6.9.4 Example for Configuring Association Between VRRP and the Interface Status....................................................207
6.9.5 Example for Configuring Association Between VRRP and BFD to Monitor the Uplink Status............................212
6.9.6 Example for Configuring Association Between VRRP and NQA to Monitor the Uplink Status...........................218
6.9.7 Example for Configuring Association Between VRRP and Routing to Monitor the Uplink Status.......................225
6.9.8 Example for Configuring VRRP on a Dot1q Termination Sub-interface...............................................................232
6.9.9 Example for Configuring VRRP on a QinQ Termination Sub-interface................................................................239
6.9.10 Example for Configuring a VRRP6 Group in Active/Standby Mode...................................................................248
6.9.11 Example for Configuring a VRRP6 Group in Load Balancing Mode..................................................................254
6.10 Common Configuration Errors.................................................................................................................................259
6.10.1 Multiple Masters Coexist in a VRRP Group.........................................................................................................259
6.10.2 VRRP Group Status Changes Frequently..............................................................................................................260
6.11 References................................................................................................................................................................260
7 EFM Configuration................................................................................................................... 262
7.1 Introduction to EFM...................................................................................................................................................263
7.2 Principles....................................................................................................................................................................263
7.2.1 Basic Concepts........................................................................................................................................................263
7.2.2 Basic Functions........................................................................................................................................................265
7.2.3 Fault Information Advertisement Between EFM and Other Modules....................................................................269
7.3 Configuration Task Summary....................................................................................................................................271
7.4 Default Configuration.................................................................................................................................................272
7.5 Configuring EFM.......................................................................................................................................................272
7.5.1 Configuring Basic EFM Functions..........................................................................................................................272
7.5.1.1 Enabling EFM Globally........................................................................................................................................272
7.5.1.2 (Optional) Setting the EFM Working Mode on an Interface................................................................................273
7.5.1.3 (Optional) Setting EFM OAMPDU Parameters...................................................................................................274
7.5.1.4 Enabling EFM on an Interface..............................................................................................................................275
7.5.1.5 Checking the Configuration..................................................................................................................................276
7.5.2 Configuring EFM Link Monitoring.........................................................................................................................276
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7.5.2.1 Detecting Minor Link Events...............................................................................................................................276
7.5.2.2 (Optional) Associating a Minor Link Event with an Interface.............................................................................278
7.5.2.3 Checking the Configuration..................................................................................................................................279
7.5.3 Configuring Remote Loopback...............................................................................................................................279
7.5.3.1 Configuring Remote Loopback On the Device in Active Mode..........................................................................279
7.5.3.2 (Optional) Configure a receiving device to ignore remote loopback requests.....................................................281
7.5.3.3 Checking the Configuration..................................................................................................................................282
7.5.4 Configuring Remote Fault Indication......................................................................................................................282
7.5.5 Configuring EFM Association.................................................................................................................................284
7.5.5.1 Configuring Association Between EFM and Interfaces.......................................................................................284
7.5.5.2 Configuring Association Between EFM and BFD...............................................................................................287
7.6 Configuration Examples.............................................................................................................................................289
7.6.1 Example for Configuring Basic EFM Functions.....................................................................................................289
7.6.2 Example for Configuring Association between EFM and BFD..............................................................................294
7.7 References..................................................................................................................................................................299
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1 Introduction to Reliability
About This Chapter
This section describes the levels of reliability requirements, measurement specifications, and
implemented technologies.
As networks rapidly develop and applications become diversified, various value-added services
such as IPTV and video conferencing are widely used. Network disconnections may affect many
services and cause losses. Demands for network infrastructure reliability are increasing.
In real-world applications, many network failures and service interruptions are caused by non-
technical factors. An effective way to enhance system reliability is to improve fault tolerance
capabilities of the system, speed up fault recovery, and reduce impact of faults on services.
1.1 Levels of Reliability Requirements
1.2 Reliability Specifications
1.3 Reliability Technologies
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1.1 Levels of Reliability Requirements
There are three requirement levels according to the objective and implementation. Table 1-1
lists three levels of reliability requirements.
Table 1-1 Levels of reliability requirements
Level Objective Implementation
1Fewer faults in the system
software and hardware
lHardware: simplified
circuit design, improved
production technique, and
reliability test
lSoftware: software
reliability design and test
2 No impact on the system
when a fault occurs
Device and link redundancy
design, switchover policy,
and switchover success rate
3 Rapid recovery from a fault
that affects the system
Fault detection, diagnosis,
isolation, and recovery
The reliability requirements at level 1 need to be considered during network device design and
production; the reliability requirements at level 2 need to be considered during network
architecture design; the reliability requirements at level 3 are met using reliability technologies
according to the network architecture and service characteristics during network deployment.
1.2 Reliability Specifications
The Mean Time Between Failures (MTBF) and Mean Time to Repair (MTTR) are used to
evaluate system reliability.
MTBF
The MTBF refers to the average time (usually expressed in hours) when a component or a device
works without any failure. A larger value of the MTBF indicates higher reliability.
MTTR
The MTTR refers to the average time that a component or a device will take to recover from
any failure. MTTR also involves device management and customer service, and is an important
specification for device maintenance.
MTTR = Fault detection time + Hardware replacement time + System initialization time + Link
recovery time + Route convergence time + Forwarding recovery time
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A smaller value of MTTR indicates higher reliability.
1.3 Reliability Technologies
Network reliability can be improved by increasing the MTBF or reducing the MTTR. Faults
caused by various factors are inevitable, so fault recovery technologies are important. The
following reliability technologies are mainly used to reduce the MTTR and meet level 3
reliability requirements.
Reliability technologies fall into fault detection technologies and protection switching
technologies.
Fault Detection Technologies
Fault detection technologies focus on fault detection and diagnosis. Table 1-2 describes the fault
detection technologies.
Table 1-2 Fault detection technologies
Technology Description Link
BFD Bidirectional Forwarding
Detection (BFD) is a unified
detection mechanism
independent of media and
protocols, and is used to
rapidly detect link faults and
monitor IP connectivity.
5 BFD Configuration
EFM EFM monitors network faults
and is for use on last-mile
Ethernet access links to users
on the network. EFM needs
to be enabled on the two
directly connected devices so
that EFM can monitor the
link between the two devices.
7 EFM Configuration
Protection Switching Technologies
Protection switching technologies focus on network recovery, and backs up hardware, link,
service information, and routing information and perform fast switching to ensure service
continuity. Table 1-3 describes protection switching technologies.
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Table 1-3 Protection switching technologies
Technology Description Link
Interface Backup Interface backup ensures
smooth services. When an
interface on a router is faulty
or bandwidth is insufficient,
interface backup allows the
router to quickly switch
services on the faulty
interface to other available
interfaces.
2 Interface Backup
Configuration
Interface Monitoring Group After network-side interfaces
are added to an interface
monitoring group, the status
changes of the network-side
interfaces trigger the status of
corresponding access-side
interfaces to change. This, in
turn, triggers an access-side
master/backup switchover of
access-side links.
3 Interface Monitoring
Group Configuration
VRRP The Virtual Router
Redundancy Protocol
(VRRP) is a fault-tolerant
protocol that allows the
device to provide the default
link when the default
becomes faulty on LANs
with multicast or broadcast
capabilities. VRRP prevents
network interruptions caused
by the fault of the single link.
6 VRRP Configuration
HSB Hot standby backup (HSB)
provides a unified backup
mechanism for service
modules. When the master
device becomes faulty, the
backup device takes over
services on the master
service, which improves
network reliability.
4 HSB Configuration
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2 Interface Backup Configuration
About This Chapter
The interface backup function allows a backup interface to transmit traffic when the primary
interface is faulty or load balance traffic when bandwidth of the primary interface is insufficient.
2.1 Introduction to Interface Backup
This section describes the definition and purpose of Interface Backup.
2.2 Principles
This section describes the implementation of Interface Backup.
2.3 Applications
This section describes the applicable scenario of Interface Backup.
2.4 Configuration Task Summary
The interface backup function allows a backup interface to transmit traffic when the primary
interface is faulty or load balance traffic when bandwidth of the primary interface is insufficient.
2.5 Default Configuration
This section describes default parameter settings of interface backup.
2.6 Interface Backup Configuration
2.7 Configuration Examples
This section provides several configuration examples of interface backup.
2.8 References
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2.1 Introduction to Interface Backup
This section describes the definition and purpose of Interface Backup.
Definition
The interface backup feature enables an interface of a device to function as a backup for another
interface. When an interface is faulty or bandwidth is insufficient, the interface backup function
allows traffic to be switched to a backup interface. The backup interface then transmits service
traffic or loads balance service traffic.
Purpose
When a router interface is faulty or bandwidth is insufficient, services will be interrupted or data
will be lost. The interface backup technology allows a backup interface to transmit or load
balance service traffic when the primary interface is faulty. This improves communication
reliability.
2.2 Principles
This section describes the implementation of Interface Backup.
2.2.1 Interface Backup in Active/Standby Mode
As shown in Figure 2-1, Interface1 is the primary interface, and Interface2 and Interface3 are
backup interfaces. In active/standby mode, only one interface transmits services at any time.
lWhen the primary interface Interface1 works properly, Interface2 and Interface3 do not
transmit services.
lThe router monitors the interface status. When the primary interface Interface1 fails, a
backup interface with the highest priority starts to transmit services.
lWhen the primary interface Interface1 is restored, traffic is switched back to the primary
interface Interface1.
Figure 2-1 Interfaces working in active/standby mode
Interface2
Interface1
Interface3
RouterA RouterB
NOTE
Interface backup in active/standby mode can only detect faults on a directly connected link. When the
upstream indirectly connected link of the primary interface is faulty, the interface backup module cannot
detect the fault, causing service interruption. To monitor the status of the entire link, associate interface
backup in active/standby mode with NQA, BFD, or routing.
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2.2.2 Load Balancing Mode
As shown in Figure 2-2, Interface1 is the primary interface, and Interface2 and Interface3 are
backup interfaces. When the load balancing mode is used, the system periodically checks
whether the traffic volume is within the allowed range:
lIf the traffic volume of Interface1 exceeds the upper threshold, the backup interface with
the highest priority is selected to load balance services together with Interface1.
lIf the load balanced traffic volume still exceeds the upper threshold, the backup interface
with the secondary highest priority is selected to load balance services with the preceding
two interfaces. This process is repeated until all the backup interfaces transmit traffic.
lWhen the traffic volume falls below the lower threshold, the backup interface with the
lowest priority participating in load balancing is shut down. This process is repeated until
only the primary interface transmits traffic.
Figure 2-2 Interfaces working in load balancing mode
Interface2 B%
A%
C%
A%+B%+C%=100%
Interface1
Interface3
RouterA RouterB
2.3 Applications
This section describes the applicable scenario of Interface Backup.
2.3.1 Interface Backup in Active/Standby Mode
As shown in Figure 2-3, the enterprise egress gateway RouterA connects to the Internet through
ADSL interface ATM3/0/0. To ensure that enterprise users can connect to the IP network when
the ADSL interface is faulty, the link of a 3G interface is used as the backup link. When the
active interface is faulty, the backup link is started to transmit services.
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Configuration Guide - Reliability 2 Interface Backup Configuration
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Figure 2-3 Interface backup application
RouterA
ATM3/0/0
Cellular0/0/0
Access
network
3G
Primary link
Backup link
Internet
DSLAM
Enterprise
2.3.2 Interface Backup in Load Balancing Mode
As shown in Figure 2-4, HostA communicates with RouterB through GE2/0/0 on RouterA. To
prevent data loss caused by insufficient bandwidth of GE2/0/0, interface backup in load
balancing mode is configured on RouterA. When the traffic volume on GE2/0/0 exceeds the
configured upper threshold, a backup interface with the highest priority is used to load balance
services. This improves reliability of data transmission.
Figure 2-4 Interface backup in load balancing mode
RouterA
GE2/0/0
10.1.1.1/24
RouterB
GE3/0/0
10.1.3.1/24
GE1/0/0
10.1.2.2/24
GE1/0/0
10.1.2.1/24
HostA HostB
GE2/0/0
10.1.1.2/24
GE3/0/0
10.1.3.2/24
192.168.1.1/24 192.168.2.1/24
Service Flow
2.3.3 Association Between Interface Backup in Active/Standby
Mode and NQA
When the upstream indirectly connected link of the primary interface is faulty, the interface
backup module cannot detect the fault, causing service interruption. The NQA technology
measures network performance and collects statistics on the response time, jitter, and packet
loss ratio. Association between interface backup and NQA enables the system to detect
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connectivity of the primary link and implement rapid switching when the primary link is faulty.
This improves reliability of service transmission.
Figure 2-5 Networking diagram of association between interface backup and NQA
Internet
GE1/0/0
2.1.1.1/24
GE1/0/0
4.1.1.2/24
GE1/0/0
2.1.1.2/24
GE1/0/0
4.1.1.1/24
RouterA RouterB
RouterC RouterD
Branch of
company
Headquarters
of company
Primary link
Internet
ATM0/0/0
3.1.1.1/24 DSLAM
PPPoA
Server
ATM0/0/0
5.1.1.1/24
Backup link
NQA packets
As shown in Figure 2-5, the egress gateway RouterA in the headquarters of company connects
to the Internet through GE1/0/0. The link between GE1/0/0 and the Internet is used as the primary
link, and the link between ATM0/0/0 (ADSL interface) and the Internet is used as the backup
link. An NQA test instance is configured on RouterA and association between interface backup
and NQA is configured on ATM0/0/0. When the link between RouterD and RouterB is faulty,
the NQA test instance can detect faults and instructs RouterA to start ATM0/0/0 to transmit
services.
2.3.4 Association Between Interface Backup in Active/Standby
Mode and BFD
When the upstream indirectly connected link of the primary interface is faulty, the interface
backup module cannot detect the fault, causing service interruption. BFD provides fast fault
detection independent of media and routing protocols. It can rapidly detect faults on the
forwarding path between two adjacent routers within milliseconds. Association between
interface backup and BFD enables the system to detect connectivity of the primary link and
implement rapid switching when the primary link is faulty. This ensures reliability of service
transmission.
Huawei AR530&AR550 Series Industrial Switch Routers
Configuration Guide - Reliability 2 Interface Backup Configuration
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Copyright © Huawei Technologies Co., Ltd.
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