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    IP Network MultipathingAdministration Guide

    Sun Microsystems, Inc.901 San Antonio RoadPalo Alto, CA 94303-4900U.S.A.

    Part Number 816-0850-10July 2001

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    Copyright 2001 Sun Microsystems, Inc. 901 San Antonio Road, Palo Alto, California 94303-4900 U.S.A. All rights reserved.

    This product or document is protected by copyright and distributed under licenses restricting its use, copying, distribution, anddecompilation. No part of this product or document may be reproduced in any form by any means without p rior written authorization of Sun and its licensors, if any. Third-party software, including font technology, is copyrighted and licensed from Sun suppliers.

    Parts of the product may be derived from Berkeley BSD systems, licensed from the University of California. UNIX is a registeredtrademark in the U.S. and other countries, exclusively licensed through X/ Open Company, Ltd.

    Sun, Sun Microsystems, the Sun logo, docs.sun.com, Answ erBook, AnswerBook2, and Solaris are trad emarks, registered trademarks, orservice marks of Sun Microsystems, Inc. in the U.S. and other countries. All SPARC trademarks are used under license and are trademarksor registered trademarks of SPARC International, Inc. in the U.S. and other countries. Products bearing SPARC trademarks are based uponan architecture developed by Sun Microsystems, Inc.The OPEN LOOK and Sun TM Graphical User Interface was developed by Sun Microsystems, Inc. for its users and licensees. Sunacknowledges the pioneering efforts of Xerox in researching and developing the concept of visual or graphical user interfaces for the

    computer industry. Sun h olds a non-exclusive license from Xerox to the Xerox Graphical User Interface, wh ich license also covers Sunslicensees who implement OPEN LOOK GUIs and otherwise comply with Suns written license agreements.Federal Acquisitions: Comm ercial SoftwareGovernment Users Subject to Standard License Terms and Conditions.

    DOCUMENTATION IS PROVIDED AS IS AND ALL EXPRESS OR IMPLIED COND ITIONS, REPRESENTATIONS A ND WARRANTIES,INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE ORNON -INFRINGEMENT, ARE DISCLAIMED, EXCEPT TO THE EXTENT THAT SUCH DISCLAIMERS ARE HELD TO BE LEGALLYINVALID.

    Copyright 2001 Sun Microsystems, Inc. 901 San Antonio Road, Palo Alto, Californie 94303-4900 Etats-Unis. Tous droits rservs.

    Ce produit ou document est protg par un copyright et distribu avec des licences qui en restreignent lutilisation, la copie, ladistribution, et la dcompilation. Aucune partie de ce produit ou document ne peut tre reproduite sous aucune forme, par quelquemoyen que ce soit, sans lautorisation pralable et crite de Sun et de ses bailleurs de licence, sil y en a. Le logiciel dtenu par des tiers, etqui comprend la technologie relative aux polices de caractres, est protg par un copyright et licenci par des fournisseurs de Sun.

    Des parties de ce produit pourront tre drives du systme Berkeley BSD licencis par lUniversit de Californie. UNIX est une marquedpose aux Etats-Unis et dans dautres pays et licencie exclusivement par X/ Open Company, Ltd.Sun, Sun Microsystems, le logo Sun, docs.sun.com, AnswerBook, AnswerBook2, et Solaris sont des marques de fabrique ou des marques

    dposes, ou m arques d e service, de Sun Microsystems, Inc. aux Etats-Unis et d ans d autres p ays. Toutes les m arques SPARC sont u tilisessous licence et sont des marques de fabrique ou des marques dposes de SPARC International, Inc. aux Etats-Unis et dans dautres pays.Les produits portant les marques SPARC sont bass sur une architecture dveloppe par Sun Microsystems, Inc.

    Linterface dutilisation graph ique OPEN LOOK et Sun TM a t dveloppe par Sun Microsystems, Inc. pour ses utilisateurs et licencis.Sun reconnat les efforts de pionniers de Xerox pour la recherche et le dveloppement du concept des interfaces dutilisation visuelle ougraphique pour lindustrie de linformatique. Sun d tient une licence non exclusive de Xerox sur linterface d utilisation gr aphique Xerox,cette licence couvrant galement les licencis de Sun qui mettent en place linterface dutilisation graphique OPEN LOOK et qui en outrese conforment aux licences crites de Sun.

    CETTE PUBLICATION EST FOURNIE EN LETAT ET AUCUNE GARANTIE, EXPRESSE OU IMPLICITE, NEST ACCORDEE, YCOMPRIS DES GARANTIES CONCERNANT LA VALEUR MARCHANDE, LAPTITUDE DE LA PUBLICATION A REPONDRE A UNEUTILISATION PARTICULIERE, OU LE FAIT QUELLE NE SOIT PAS CONTREFAISANTE DE PRODUIT DE TIERS. CE DENI DEGARANTIE NE SAPPLIQUERAIT PAS, DANS LA MESURE OU IL SERAIT TENU JURIDIQUEMENT NUL ET NON AVENU.

    PleaseRecycle

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    Multipathing Conguration File 24

    Failure Detection Time 25

    Failback 25

    Track Interfaces Only With Groups Op tion 25

    2. Deploy ing Network Mul tipath ing 27

    Conguring Multipathing Interface Groups 27Conguring Multipathing Interface GroupsTask Map 28

    How to Congure a Multipathing Interface Group w ith Two Interfaces 28

    How to Congure a Multipathing Group Where One of the Interfaces is aStandby Interface 32

    How to Display the Group to Which a Physical Interface Belongs 34

    How to Add an Interface To a Group 35

    How to Remove an Interface From a Group 35

    How to Move an Interface From an Existing Group to a Different Group 36

    Replacing a Physical Interface That H as Failed 37

    How to Remove a Physical Interface That Has Failed 37

    How to Replace a Physical Interface That Has Failed 38

    Recovering a Physical Interface That Was Not Present at System Boot 38

    How to Recover a Physical Interface That Was Not Present at System Boot 38

    Conguring the Multipathing Conguration File 40

    How to Congure the Multipathing Conguration File 40

    Glossary 43

    Index 45

    4 IP Network Multipathing Administration Guide July 2001

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    Preface

    The IP Network Mu ltipathing Administration Guide provides information aboutconguring and managing the IP Network Multipathing framework installed in yourSolaris TM Operating Environment. This book assum es that you have already installedthe SunOS TM 5.8 operating system, and you have set up any networking softwarethat you plan to use. The SunOS 5.8 operating system is part of the Solaris productfamily, w hich includes many features, such as th e Solaris Common Desktop

    Environment (CDE). The SunOS 5.8 operating system is compliant with AT&TsSystem V, Release 4 operating system.

    Note - The Solaris operating environment runs on two types of hardware, orplatforms: SPARC TM and IA. The Solaris operating environment run s on both 64-bitand 32-bit ad dress spaces. The information in this d ocument p ertains to bothplatforms an d add ress spaces unless called ou t in a sp ecial chapter, section, note,bullet, gure, table, example, or code examp le.

    Who Should Use This Book This book is intended for anyone responsible for administering one or more systemsrunning the Solaris 8 release. To use this book, you should have one to two years of UNIX system adm inistration experience. Attending UNIX system administrationtraining courses might be helpful.

    5

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    TABLE P1 Typographic Conventions

    Typeface orSymbol Meaning Example

    AaBbCc123 The names of commands, les, anddirectories; on-screen computer output

    Edit your .login le.

    Use ls a to list all les.

    machine_name% you have

    mail.

    AaBbCc123 What you type, contrasted withon-screen computer output

    machine_name% su

    Password:

    AaBbCc123 Command-line placeholder: replacewith a real name or value

    To delete a le, type rm lename .

    AaBbCc123 Book titles, new words, or terms, orwords to be emphasized.

    Read Chapter 6 in UsersGuide .

    These are called class options.

    You m ust be root to do this.

    Shell Prompts in Command ExamplesThe following table shows the default system prompt and superuser prompt for theC shell, Bourne shell, and Korn shell.

    TABLE P2 Shell Promp ts

    Shell Prompt

    C shell prompt machine_name%

    C shell superuser prompt machine_name#

    Bourne shell and Korn shell prompt $

    Bourne shell and Korn shell superuserprompt

    #

    Preface 7

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    8 IP Network Multipathing Administration Guide July 2001

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    CHAPTER 1

    Overview of IP Network Multipathing

    IP Network Multipathing provides both load spreading and failover when you havemu ltiple netw ork interface cards connected to the same IP link (for example,Ethernet).

    4 Introduction on page 9

    4 IP Network Multipathing Features on page 10

    4 Commun ication Failures on page 10

    4 IP Network Multipathing Components on page 11

    4 Solaris N etwork Mu ltipathing on page 12

    4 Administering Mu ltipathing Groups with Multiple Ph ysical Interfaces on page14

    4 Administering Multipathing Groups With a Single Physical Interface on page 21

    4 Removing Network Adapters From Multipathing Groups on page 22

    4 Detached Network Adapters on page 22

    4 Multipathing Daemon on page 23

    4 Multipathing Conguration File on page 24

    IntroductionIP Network Multipathing provides your system with the following capabilities:

    4 Recovery from single-point failures with network adapters

    4 Increased trafc throughp ut

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    If a failure occurs in the network adapter, and if you have an alternate adapterconnected to the same IP link, the system switches all the n etwork accessesautomatically from the failed adap ter to the alternate ad apter. This process ensu resuninterrupted access to the network. Also, when you have multiple network adapters connected to the same IP link, you achieve increased trafc throughput byspreading the trafc across multiple network adapters.

    Note - Other IP related documents, su ch as RFC 2460, use the term link instead of IPlink . This document uses the term IP link to avoid confusion with IEEE 802. In IEEE802, link refers to a single w ire from an Ethernet N IC to an Ethernet sw itch.)

    See IP link denition in the Glossary or refer to Table 11.

    IP Network Multipathing FeaturesThe Solaris implementation of IP N etwork Multipathing provides the followingfeatures:

    4 Failure Detection Ability to detect when a network adapter has failed andautomatically switching ( failover ) the network access to an alternate network adapter. This assumes that you have congured an alternate network adapter. SeeDetecting Physical Interface Failures on page 12 for more information.

    4 Repair De tection Ability to detect when a n etwork ad apter that failed p reviouslyhas been repaired and automatically sw itching back ( failback ) the n etwork access toan alternate n etwork ad apter. This assumes that you have enabled failbacks. SeeDetecting Physical Interface Repairs on page 13 for more information.

    4 Outbound Load Sp reading Outbound network packets are spread acrossmu ltiple network adap ters without affecting the ordering of packets in order toachieve higher throughput. Load spreading occurs only when the network trafcis owing to m ultiple d estinations using mu ltiple connections.

    Communication FailuresCommu nication failures can occur in the following ways:

    1. Transmit/ receive path of the NIC can stop transmitting packets.

    2. Attachment of the NIC to the link is down.

    3. Port on the sw itch d oes not transmit/ receive packets.

    4. Physical interface in a group n ot present at system boot.

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    5. Host on the other end is not respond ing or the router that is forwarding thepackets is not responding.

    The Solaris implementation of IP Network Multipathing addresses the rst fourtypes of communication failures.

    IP Network Multipathing ComponentsThe following table identies and describes the components that make up IPNetwork Multipathing.

    TABLE 11 IP Network Multipathing Components

    Component Description

    IP Lin k A com mu nication fa cility or m ed iu m ov er w h ich n od es cancommunicate at the link layer. The link layer is the layerimmediately below IPv4/ IPv6. Examples include Ethernets(simple or bridged) or ATM networks. One or more IPv4subnet numbers/ prexes are assigned to an IP link. A subnetnumber/ prex can not be assigned to more than one IP link. InATM LANE, an IP link is a single emulated LAN. When usingARP, the scope of the ARP protocol is a single IP link.

    Network Interface Card(NIC)

    Network adapter which is either internal or a separate card thatserves as an interface to a link.

    Physical in terface A nodes a t tachment to a l ink . Th is a t tachment i s o ftenimplemented as a device driver plus a network adapter. Somenetwork adapters can have multiple points of attachment, forexample, qfe. The usage of Network adapter in this documentrefers to a "Single Point of Attachment."

    Physical interface group The set of physical interfaces on a system that are connected tothe same link. They are identied by assigning the same(non-null) character string name to all the physical interfaces inthe group.

    Physical interface groupname

    A name assigned to a physical interface that identies thegroup. The name is local to a system. Multiple ph ysicalinterfaces, sharing the same group name, form a physicalinterface group.

    Failu re detect ion The process o f detect ing when a NIC or the path from the NICto some layer 3 device no longer works.

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    TABLE 11 IP Network Multipathing Components (continued)

    Component Description

    Repa ir d e tect io n Th e p rocess o f d e tect in g wh en a NIC o r t he p a th from t h e NICto some layer 3 device starts operating correctly after a failure.

    Fa ilo ver Th e p ro ces s o f sw it ch in g n et wo rk a cces s fro m a fa iled in ter fa ceto a good physical interface. Network access includes IPv4

    unicast, multicast, and broadcast trafc, as well as IPv6 unicastand multicast trafc.

    Fa ilb ack Th e p ro ces s o f sw it ch in g b ack n et wo rk a ccess t o a n in ter fa cedetected as having been repaired.

    Standby In ter face A physical inter face that i s no t used to carry data t rafc un lesssome other physical interface in the group has failed.

    Solaris Network MultipathingThe following components implement Solaris network mu ltipathing:

    4 Multipathing daemon in.mpathd

    4 IP

    The in.mpathd daemon detects failures an d implements various p olicies forfailover and failback. After in.mpathd detects a failure or repair, in.mpathd sendsan ioctl to do the failover or failback. IP, which implements the ioctl, does thenetwork access failover transparently and automatically.

    Caution - You should not u se Alternate Pathing w hile u sing IP Network Multipathing on the same set of NICs. Likewise, you should not use IP Network Multipathing while using Alternate Pathing. You can use Alternate Pathing an d IPNetwork Multipathing at the same time on different sets of NICs.

    Detecting Physical Interface FailuresThe in.mpathd daemon sends ICMP echo probes to the targets connected to thelink on all the interfaces that belong to a group to d etect failures and repair. Afteryou add an interface to a multipathing group and assign a test address, the daemon

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    sends probes to detect failures on all the interfaces of the multipathing group. Howto Congure a Multipathing Interface Group with Two Interfaces on page 28describes the steps you perform to congure test address and groups.

    Because in.mpathd determines what targets to probe d ynamically, you cannotcongure the targets. Routers connected to the link are chosen as targets for p robing.If no routers exist on the link, arbitrary hosts on the link are chosen. A multicastpacket sent to the all hosts multicast address ( 224.0.0.1 in IPv4 and ff02::1 inIPv6) determines the arbitrary hosts. The rst few hosts that respond to the echo

    packets are chosen as targets for p robing. If in.mpathd cannot nd routers or hoststhat responded to ICMP echo packets, in.mpathd cannot detect failures.

    To ensure that each NIC in the group functions properly, in.mpathd probes all thetargets separately through all the interfaces in the multipathing group. If there are noreplies to ve consecutive probes, in.mpathd considers the interface as havingfailed. The probing rate d epends on the failure d etection time (FDT). The d efaultvalue for failure detection time is 10 seconds. The in.mpathd (1M) man pagedescribes how to change the failure detection time. For a failure detection time of 10seconds, the probing rate is approximately one probe every two seconds.

    If ve consecutive probes fail, in.mpathd considers the interface as having failed.After a failure is detected, failover of all network access takes place from the failedinterface to another functional interface in the group. If you have congured astandby interface, in.mpathd chooses the standby interface for failover of IPaddresses, broadcasts, and multicast memberships. If you have not congured astandby interface, in.mpathd chooses the interface with the least number of IPaddresses.

    Physical interfaces in the same group that are not present at system boot represent aspecial case of failure detection. The startup script /etc/init.d/network detectsthese types of failure. This typ e of failure d isplays error messages similar to thefollowing:

    moving addresses from failed IPv4 interfaces: hme0 (moved to hme1)moving addresses from failed IPv6 interfaces: hme0 (moved to hme1)

    Currently, this type of failure cannot be automatically repaired by a failback. SeeHow to Recover a Physical Interface That Was N ot Present at System Boot on page38.

    Detecting Physical Interface RepairsTo detect if a physical interface has been repaired, in.mpathd sends probes throughthe failed NIC. When an interface fails, all addresses are m oved to another functionalinterface in the group. Because in.mpathd needs an address for probing so that itcan detect repairs, you must congure a test IP address that will not move during

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    the failover. Moreover, you should not allow a normal ap plication to u se this testadd ress, because the failover of network access will not take p lace for theseadd resses. How to Congu re a Multipathing Interface Group with Two Interfaceson page 28 describes the steps that you perform. in.mpathd considers the interfacerepaired if it receives responses to 10 consecutive probe packets. Then, if in.mpathddetects a failure, failback of all network access takes place to the repaired interface.

    As noted in Detecting Physical Interface Failures on page 12, automatic failback isnot supported for physical interfaces that are not present at system boot. See How

    to Recover a Physical Interface That Was Not Present at System Boot on page 38.

    Link FailuresIf all the N ICs ap pear to fail at the same time, it is considered a link failure andin.mpathd does not do any failovers. This is also true when all the targets fail atthe same time. In this case, in.mpathd ushes all of its current targets anddiscovers new targets (see Detecting Physical Interface Failures on page 12).

    Administering Multipathing Groupswith Multiple Physical InterfacesThis section d escribes how you enable IP Network Multipathing. To u se the IPNetwork Multipathing feature, you should have more than one physical interfaceconnected to the same IP link. For example, the same Ethernet switch or the same IPsubnet, congured under the same multipathing group, works. If you have just onephysical interface, refer to Administering Multipathing Groups With a SinglePhysical Interface on page 21.

    Multipathing groups are identied by non-null names. For example, math-link,

    bio-link, and chem-link, m ake good names. The n ames typ ically represent w herethese groups are connected. When failure is detected in one of the network adaptersin the multipathing group , all network access is failed over from the failed ad apter tothe good adap ter in th e group . The failover of network access includ es IPv4 unicast,broadcast, and multicast trafc, as well as IPv6 unicast and multicast trafc. For IPnetwork mu ltipathing to function p roperly, the following conditions mu st exist forthe network adap ters that are part of the same multipathing group:

    1. You m ust p ush and congure the same set of STREAMS modules on all network adapters in the multipathing group.

    2. If you have p lumbed IPv4 on one network adapter, then you m ust plumb IPv4 onall network adapters in the multipathing group.

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    3. If you have p lumbed IPv6 on one network adapter, then you mu st plumb IPv6 onall network adapters in the multipathing group.

    4. All Ethernet network adap ters in the system should have un ique MAC address inthe case of ethernets. This is achieved by setting local-mac-address? to true in theopenboot PROM for SPARC platforms. Nothing needs to be done for IA (x86)platforms.

    5. All network adap ters of the multipathing group mu st be connected to the same IPlink.

    6. The mu ltipathing grou p should not contain dissimilar interfaces. The interfacesthat are grouped together should be of the same interface type that is dened in /usr/include/net/if_types.h . For example, you cannot combine Ethernetwith Token ring, and you cannot combine a Token bu s w ith ATM (asynchronoustransfer mode).

    7. When you u se IP network m ultipathing w ith ATMs, you mu st congure the ATMfor LAN emulation (multipathing over classical IP instances is not currentlysupported).

    Note - The fourth condition concerns all interfaces in the system, not just thosebelonging to the multipathing group.

    For the adapters which do not come with factory set unique mac addresses, you canmanually congure a mac address for each adapter as a work around. For example,use the ifconfig ether command in a start script le.

    Note - The mac addresses congured manually will not be maintained across systemreboot. You are responsible for choosing u nique m ac ad dresses. IP Network Multipathing might behave unpredictably if the mac address of adapters are notunique.

    Group ing Physical Interfaces

    You u se the ifconfig command to congure groups. This command uses a newgroup parameter that requires a group name and places both the IPv4 and IPv6instance of the interface in that group. The group parameter has the followingsyntax:

    ifconfig interface-name group group-name

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    IPv4 Test AddressesThe in.mpathd multipathing daemon requires a test IP address for detectingfailures and repairs. You mu st u se a routeable ad dress for this IP ad dress. That is, thesubnet p rex of the add ress must be kn own to any rou ters present on the link. Youuse the ifconfig commands new failover option to congure a test address.Use the following syntax to congure a test address:

    # ifconfig interface-name addif ip-address -failover up

    For , use the parameters required by your conguration. See theifconfig (1M) man page for descriptions. How to Congure a MultipathingInterface Group with Two Interfaces on page 28 shows the steps you perform for anIPv4 test add ress.

    For example, to add a new logical interface with an address of 19.16.85.21 , thenetmask and broadcast address set to the default value, and also congure theinterface with a test add ress, type the following:

    # ifconfig hme0 addif 19.16.85.21 netmask + broadcast + -failover up

    Note - You m ust m ark an IPv4 test address as deprecated to p revent app licationsfrom using the test address (see How to Congure a Multipathing Interface Groupwith Two Interfaces on page 28).

    Use failover without the dash to turn on the failover attribute of the address.

    Note - All test IP addresses in a multipathing group must use the same network prex. That is, the test IP addresses must belong to a single IP subnet.

    IPv6 Test AddressesTo congure an IPv6 test add ress, you use the link-local ad dress itself, becauselink-local addresses are tied to the p hysical interface. Thus, you do not n eed aseparate IP ad dress in the IPv6 case. For IPv6, the failover option has thefollowing syntax:

    # ifconfig interface-name inet6 -failover

    How to Congure a Multipathing Interface Group with Two Interfaces on page 28shows the steps you perform for an IPv6 test address.

    When a multipathing group has both IPv4 and IPv6 plumbed on all the groupsinterfaces, you might not need a separate IPv4 test add ress. The in.mpathd daemoncan probe the interfaces using an IPv6 link-local address. IPv6 link-local addressesare created when IPv6 is plumbed.

    Use failover without the dash to turn on the failover attribute of the address.

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    For example, to create the group test with the following conguration:

    4 Physical interface hme0 with address 19.16.85.19

    4 A logical interface address of 19.16.85.21

    4 With deprecated an d failover set

    4 Sets the netmask and broadcast address to the default value

    You add the following line to the /etc/hostname.hme0 le:

    19.16.85.19 netmask + broadcast + group test up \addif 19.16.85.21 deprecated -failover netmask + broadcast + up

    How to Congure a Multipathing Interface Group with Two Interfaces on page 28shows the steps you perform to congure the IPv4 hostname le.

    For IPv6 setup, add a line to the /etc/hostname6. interface le using the followingsyntax:

    group group-name up

    For example, to create a test group for hme0 with an IPv6 test address, add thefollowing line to the /etc/hostname6.hme0 le:

    -failover group test up

    How to Congure a Multipathing Interface Group with Two Interfaces on page 28shows the steps you perform to congure the IPv6 hostname6 le.

    Conguring Standby InterfacesYou can congure mu ltipathing grou ps with stand by interfaces. As the name implies,the interface is considered as standby and is not used unless some other interface inthe grou p fails.

    The standby interface is not u sed to send normal d ata p ackets. Consequently, limitedtrafc ows on a stand by interface. You mu st congure stand by interfaces with a testaddress to insure that probes are sent to determine if the interface is functional. If you do not congure standby interfaces with a test address, the interface is notchosen for failovers w hen another interface in the grou p fails. A standby interfacemight carry trafc und er the following conditions:

    4 If another host on the network communicates with a host using the standbyinterface ad dress, the stand by interface is subsequently used for incoming packets.

    4 Applications binding (either using bind or using IP_ADD_MEMBERSHIP) to theadd ress hosted on the standby interface might continue to generate trafc usingthe standby interface.

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    Thus, the system does not n ormally select a standby interface (except for probes),unless it is explicitly chosen by an application. If some interface in the group fails, allnetwork access is failed over to the standby interface. To congure a standbyinterface, you use the ifconfig commands new standby parameter using thefollowing syntax:

    # ifconfig interface-name standby group group-name

    How to Congure a Multipathing Group Where One of the Interfaces is a StandbyInterface on page 32 shows the steps you perform.

    The in.mpathd daemon sends probes on the standby interface once a test address iscongured on the stand by interface. You should congure only test add resses on astandby interface. If any other address is added on the standby, the addition of theseaddresses will fail. If standby is marked on an interface which already has addressesother than test addresses, automatic failover of these addresses will take place to adifferent interface in th e group , leaving behind only the test add ress, if there is one.It is advisable not to congure non-test address on a standby interface.

    You need to mark the ad dress as a test add ress by using the ifconfig commandsdeprecated an d failover option before setting standby or setting up .

    To congure a test address on a standby interface, use the following syntax:

    # ifconfig interface-name plumb ip-address deprecated -failover standby up

    For , use the parameters required by your conguration. See theifconfig (1M) man page for descriptions.

    Note - Standby interfaces are n ot u sed for failover if there is no test add resscongured on that interface.

    For example, to create a test add ress with the following conguration:

    4 Physical interface hme2 as a standby interface

    4 Address of 19.16.85.22

    4 With deprecated an d failover set

    4 Sets the netmask and broadcast address to the default value

    You type the following command line:

    # ifconfig hme2 plumb 19.16.85.22 netmask + broadcast + deprecated -failover standby up

    Note - The interface is marked as a standby interface only after the add ress ismarked as a NOFAILOVER ad dress.

    How to Congure a Multipathing Group Where One of the Interfaces is a StandbyInterface on page 32 shows the steps you perform.

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    You can clear a stan db y interface using the following synta x:

    # ifconfig interface-name -standby

    Administering Multipathing GroupsWith a Single Physical InterfaceWhen you have only one network adap ter in the mu ltipathing group, you cancongure the network adapter to detect failures on that NIC alone.

    Because failovers cannot occur with only one NIC in the group, you do not need aseparate test add ress on each of the p hysical interface in the group. You cancongure the normal address as an IFF_NOFAILOVER address, which is sufcientfor the daemon to send out probes on that interface. Unlike the multiple physicalinterface case, you do not have to mark it deprecated. Because there is only oneinterface in the group, addresses can not failover to a different interface. Hence,using this address does not cause any application failures.

    Use the following syntax to congure the interfaces IPv4 address as a NOFAILOVER:# ifconfig interface-name -failover group group-name

    For IPv6, use the following syntax:

    # ifconfig interface-name inet6 -failover group group-name

    When the daemon detects failures, the interface is marked and logged appropriatelyon the console.

    Note - You cannot verify w hether the target being probed has failed or the NIC hasfailed, because there is only one physical interface through which the target can beprobed. If there is only one default router on the subnet, you should turn off mu ltipathing when there is a single p hysical interface in the group. If a separate IPv4and IPv6 default router exists (or mu ltiple d efault routers exist), there is at least m orethan one target to probe. Hence, it is safe to turn on multipathing.

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    Removing Network Adap ters FromMultipathing Group sWhen you execute the ifconfig commands group parameter with a null string,the interface is removed from the existing group (see How to Remove an Interface

    From a Group on page 35). Be careful w hen removing interfaces from a group. If some other interface in the m ultipathing group failed, a failover could havehappened earlier. For example, if hme0 failed previously, all addresses are failed overto hme1 (assuming hme1 is part of the same group). Removing hme1 from the groupcauses in.mpathd to move all the failover addresses back to some other interface inthe group. If no other interfaces are functioning in the group, failover might notrestore all the network accesses.

    Similarly, when an interface is part of the group and it needs to be unplumbed, youshould remove it from the group rst, and then ensure that it has all the original IPaddresses congured on it. The in.mpathd daemon tries to restore the originalconguration of an interface that is removed from the group. You need to ensure thatthe conguration is restored before u nplum bing the interface. Refer to MultipathingDaemon on page 23 to see how interfaces look before and after a failover.

    Detached Network AdaptersDynamic Reconguration (DR) uses IP Network Multipathing to d ecommission aspecic network device without impacting existing IP users. Before a NIC isDR-detached (off-lined), all failover IP addresses hosted on that NIC areautomatically failed over to another NIC in the same IP Network Multipathinggroup. The test addresses are brought d own and the NIC unplumbed.

    Also, with the IP Network Multipathing reboot-safe feature, the static IP add resses inthe /etc/hostname.* le that are associated with the missing card are h ostedautomatically on an alternate interface within the same IP Network Multipathinggroup. H owever, these add resses w ill not be m oved back to the original interfaceautomatically if the original interface is inserted back into the system at a later time.

    Note - NIC attaches and re-attaches require m anual intervention.

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    ## Time taken by mpathd to detect a NIC failure in ms. The minimum time# that can be specified is 100 ms.#FAILURE_DETECTION_TIME=10000#

    # Failback is enabled by default. To disable failback turn off this option#FAILBACK=yes#

    # By default only interfaces configured as part of multipathing groups# are tracked. Turn off this option to track all network interfaces# on the system#TRACK_INTERFACES_ONLY_WITH_GROUPS=yes

    How to Congure the Multipathing Conguration File on page 40 shows the stepsyou perform to congure the /etc/default/mpathd conguration le.

    Failure Detection TimeYou can set a lower value of failure d etection time. Sometimes these values m ightnot be achieved if the load on the network is too high. Then in.mpathd prints amessage on the console, indicating that the time cannot be met. It also prints the timethat it can meet currently. If the response comes back correctly, in.mpathd meetsthe failure d etection time provided in this le.

    Failback After a failover, failbacks take place when the failed interface is repaired. However,in.mpathd does not failback the interface if FAILBACK is set to no .

    As noted in Detecting Physical Interface Failures on page 12, automatic failback isnot supported for physical interfaces that are not present at system boot. See Howto Recover a Physical Interface That Was Not Present at System Boot on page 38.

    Track Interfaces Only With Groups OptionBy turning off this op tion, in.mpathd tracks all interfaces in the system. When afailure is detected, an app ropriate message is logged on th e console. For this optionto function properly, Ethernet add resses on all the interfaces m ust be unique.

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    Grouping Physical Interfaces on page 15 provides ad ditional information.

    Conguring Multipathing Interface GroupsTask Map

    TABLE 21Conguring Multipathing Interface Group sTask Map

    Task Description For Instructions, Go to ..

    Conguring a multipathinginterface group with two interfaces.

    Use the ifconfig command, thegroup parameter, failoveroption, the deprecated option,and the /etc/hostname. interfacele

    How to Congure a MultipathingInterface Group with TwoInterfaces on page 28

    Conguring a multipathing groupwhere one of the interfaces is astandby interface

    Use the ifconfig command, thegroup parameter, standbyparameter, failover option, andth e /etc/hostname. interface le

    How to Congure a MultipathingGroup Where One of the Interfacesis a Standby Interface on page 32

    Displaying the group to which aphysical interface belongs

    Use the ifconfig command andthe interface n ame

    How to Display the Group toWhich a Physical InterfaceBelongs on page 34

    Ad d in g an in t er face t o a g ro u p Use t h e ifconfig command andthe interface n ame

    How to Add an Interface To aGroup on page 35

    Removing an interface from agroup

    Use the ifconfig command anda null string to disable IP network multipathing

    How to Remove an InterfaceFrom a Group on page 35

    Moving an interface from anexisting group to a different group

    Use the ifconfig command andth e group parameter

    How to Move an Interface From

    an Existing Group to a DifferentGroup on page 36

    How to Congure a Multipathing Interface Groupwith Two Interfaces1. Become superuser.

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    2. Place each physical interface into a multipathing group by typing the fo llow ingcommand.

    # ifconfig interface-name group group-name

    For example, to place hme0 an d hme1 under group test , you type the followingcommands:

    # ifconfig hme0 group test# ifconfig hme1 group test

    3. Congure a test address f or all the physical interfaces.

    a. For an IPv4 test address, type the fo llow ing command.

    Note - This step assumes that you have already congured your physicalinterfaces add resses.

    # ifconfig interface-name addif ip-address -failover deprecated up

    For example, to congure a test address on hme0 with the followingconguration:

    4 Address set to 19.16.85.21

    4 Netmask and broadcast address set to the default value

    4 failover an d deprecated options set

    You type the following command :

    # ifconfig hme0 addif 19.16.85.21 netmask + broadcast + -failover deprecated up

    You can check the congu ration by typ ing the following:

    # ifconfig hme0:1hme0:1: flags=9000843 mtu 1500index 2 inet 19.16.85.21 netmask ffffff00 broadcast 19.16.85.255

    Note - You m ust m ark an IPv4 test address as d eprecated to p reventapplications from using the test address.

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    To congure a test address on hme1 with the following conguration:

    4 Address set to 19.16.85.22

    4 Netmask and broadcast address set to the default value

    4 failover an d deprecated options set

    Type the following command:

    # ifconfig hme1 addif 19.16.85.22 netmask + broadcast + -failover deprecated up

    b. For an IPv6 test address, type the fol low ing command.

    # ifconfig interface-name inet6 -failover

    Note - Because you have already placed the physical interfaces w ith IPv4addresses into a multipathing group, physical interfaces with IPv6 addressesare also implicitly placed in the same multipathing group. If you had placedphysical interfaces with IPv6 addresses into a multipathing group rst, thenphysical interfaces with IPv4 ad dresses wou ld have been also implicitlyplaced in the same multipathing group.

    For example, to congure hme0 with an IPv6 test address, you type thefollowing command:

    # ifconfig hme0 inet6 -failover

    You can check the conguration by typ ing the following:

    # ifconfig hme0 inet6hme0: flags=a000841 mtu 1500 index 2

    inet6 fe80::a00:20ff:feb9:17fa/10groupname test

    Note - You d o not need to mark an IPv6 test address as dep recated to p reventapplications from using the test add ress.

    For the second interface, hme1 , type the following command:

    # ifconfig hme1 inet6 -failover

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    For example, to create a test group for hme0 with an IPv6 address, add thefollowing line to the /etc/hostname6.hme0 le:

    -failover group test up

    Similarly, to place hme1 under the same group test and congure a testaddress, add the following line to the /etc/hostname6.hme1 le:

    -failover group test up

    Note - To add more interfaces to the multipathing group, repeat steps 1 through 3.New interfaces can be added to an existing group on a live system. However,changes are lost across reboots.

    How to Congure a Multipathing Group WhereOne of the Interfaces is a Standby InterfaceThe examples used in this procedure assume that hme1 will be congured as thestandby interface.

    Note - A standby interface has only a test address.

    1. Do steps 1 and 2 in How to Congure a Multipathing Interface Group withTwo Interfaces on page 28.

    2. Congure test address on all physical interfaces using the following substeps.

    a. For the non -standby i nterface, such as hme0 , do step 3 in How to Congurea Multipathing Interface Group with Two Interfaces on page 28.

    b. For a standby interface, congure a test address by typing the f ollow ing

    command.

    Note - A standby interface can have only a test address. A standby interfacecannot have any other IP address.

    # ifconfig interface-name plumb ip-address deprecated -failover standby up

    Note - You mu st set the failover option before the standby option andthe standby option before up .

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    For , use the parameters required by your conguration.See the ifconfig (1M) man page for descriptions.For example, to create a test add ress with the following conguration:

    4 Physical interface hme1 as a standby interface

    4 Address of 19.16.85.22

    4 With deprecated an d failover set

    4 Sets the netmask and broadcast address to the default value

    You type the following command :

    # ifconfig hme1 plumb 19.16.85.22 netmask + broadcast + deprecated -failover standby up

    You can check the results by typ ing the following:

    # ifconfig hme1flags=69040843

    mtu 1500 index 4 inet 19.16.85.22 netmask ffffff00 broadcast 19.16.85.255groupname test

    For IPv6, to create a test address, type the following command:

    ifconfig hme1 plumb -failover standby up

    The INACTIVE ag indicates that this interface is not used for any outboundpackets. When a failover takes p lace to this standby interface, the INACTIVE agis cleared.

    3. (You do this step onl y if you w ant to preserve the conguration across reboots.)To preserve the conguration across reboots, do the following substeps.

    a. For IPv4, edit the /etc/hostname. interface le and add the following line.

    interface-address group group-name up \addif logical-interface -failover deprecated up

    Note - This test IP address is congured only on the next reboot. If you wantthe conguration invoked in the current session, do steps 1 and 2.

    For example, to create a group test with the following conguration forhme0 :

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    4 Physical interface hme0 with add ress 19.16.85.19

    4 A logical interface address of 19.16.85.21

    4 With deprecated an d failover set

    4 Sets the netmask and broadcast address to the default value

    You add the following line to the /etc/hostname.hme0 le:

    19.16.85.19 netmask + broadcast + group test up \addif 19.16.85.21 deprecated -failover netmask + broadcast + up

    Similarly, to place the standby interface hme1 under the same group test an dcongure a test address, type the following command:

    19.16.85.22 netmask + broadcast + deprecated + group test -failover standby up

    b. For IPv6, edit the /etc/hostname6. interface le and add the followingline.

    -failover group group-name up

    Note - This test IP address is congured only on the next reboot. If you wantthe conguration invoked in the current session, do steps 1 and 2.

    For example, to create a test group for hme0 with an IPv6 address, add thefollowing line to the /etc/hostname6.hme0 le:

    -failover group test up

    Similarly, to place the standby interface hme1 under the same group test an dcongure a test address, add the following line to the /etc/hostname6.hme1 le:

    -failover group test standby up

    How to Display the Group to Which a PhysicalInterface Belongs1. Become superuser.

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    2. On a command line, type the following command.

    # ifconfig interface-name

    For example, to display the group name for hme0 , you type the following command:

    # ifconfig hme0

    hme0: flags=9000843 mtu 1500 index 2inet 19.16.85.19 netmask ffffff00 broadcast 19.16.85.255groupname test

    To display the group name for only the IPv6 instance, you type the followingcommand:

    # ifconfig hme0 inet6hme0: flags=a000841 mtu 1500 index 2

    inet6 fe80::a00:20ff:feb9:19fa/10groupname test

    How to Add an Interface To a Group1. Become superuser.

    2. On a command line, type the following command.

    # ifconfig interface-name group group-name

    For example, to add hme0 to the group test , you type the following command:

    # ifconfig hme0 group test

    How to Remove an Interface From a Group1. Become superuser.

    2. On a command line, type the following command.

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    # ifconfig interface-name group ""

    The quotation marks indicate a null string.

    For example, to remove hme0 from the group test , you type the followingcommand:

    # ifconfig hme0 group ""# ifconfig hme0hme0: flags=9000843 mtu 1500 index 2

    inet 19.16.85.19 netmask ffffff00 broadcast 19.16.85.255# ifconfig hme0 inet6hme0: flags=a000841 mtu 1500 index 2

    inet6 fe80::a00:20ff:feb9:19fa/10

    Removing Network Adapters From Multipathing Groups on page 22 providesadd itional information.

    How to Move an Interface From an ExistingGroup to a Different Group1. Become superuser.

    2. On a command line, type the follow ing command.

    # ifconfig interface-name group group-name

    Note - Placing the interface in a n ew group automatically removes it from anyexisting group.

    For example, to remove hme0 from group test and place it in group cs-link , youtype the following:

    # ifconfig hme0 group cs-link

    This removes the interface from any existing group and then puts the interface in thegroup cs-link.

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    Replacing a Physical Interface That HasFailedYou mu st d o the following manu al steps before replacing a physical interface thathas failed. The following procedures use physical interfaces hme0 an d hme1 as

    example interfaces. The p rocedures assume that both interfaces are in a mu ltipathinggroup and that hme0 has failed. The p rocedures also assume that the logical interfacehme0:1 has the test address.

    Note - These procedures assume that you are replacing the failed interface with thesame physical interface name (for example, hme0 with hme0 ).

    How to Remove a Physical Interface That HasFailed

    Note - You can skip step 1 if the test ad dress is plumbed using the/etc/hostname.hme0 le.

    1. Retrieve the test address conguration by typing the foll owi ng command.

    # ifconfig hme0:1

    hme0:1:flags=9040842mtu 1500 index 3inet 129.146.233.250 netmask ffffff00 broadcast 129.146.233.255

    You need this information to replumb the test ad dress wh en replacing theph ysical interface.

    See Using the hostname File to Congure Groups and Test Addresses on page18 for details on how to congure test addresses using the hostname le.

    2. Refer to the cfgadm (1M) man page, Sun Enterprise 6x00, 5x00, 4x00, and 3x00 Systems Dynamic Reconguration Users Guide , or Sun Enterprise 10000 Dynamic Reconguration User Guide for a description of how to remove thephysical interface.

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    How to Replace a Physical Interface That HasFailed1. Refer to the cfgadm (1M) man page, Sun Enterprise 6x00, 5x00, 4x00, and

    3x00 Systems Dynamic Reconguration Users Guide , or Sun Enterprise 10000 Dynamic Reconguration User Guide for a description of how to replace thephysical interface.

    2. Plumb in and bring up the test address by typing the follow ing command.

    # ifconfig hme0

    Note - The test address conguration is the same as that congured inth e /etc/hostname.hme0 le. Using the previous procedure, the testconguration is the same conguration that is displayed in step 1.

    This triggers the in.mpathd daemon to resume probing. As a result of thisprobing, in.mpathd will detect the repair. Consequently, in.mpathd causes theoriginal IP address to failback from hme1 .

    See Conguring Test Addresses on page 16 for more details about how to

    congure test ad dresses.

    Recovering a Physical Interface ThatWas Not Present at System BootYou mu st d o th e following manu al steps before recovering a physical interface thatwas not present at system boot. The following procedure uses p hysical interfaces

    hme0 an d hme1 as examp le interfaces. The p rocedure assumes that both interfacesare in a m ultipathing group and that hme0 was not present at system boot.

    How to Recover a Physical Interface That Was NotPresent at System Boot1. Retrieve the f ailed netw ork info rmation from the console log failure error

    message.

    See the syslogd (3C) man page. The error message might be similar to thefollowing message:

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    # ifconfig hme0 removeif 1.2.3.5# ifconfig hme0 removeif 1.2.3.6

    5. Recongure the IPv4 information for the replaced physical interface by typingthe following command for each interface that was removed.

    # ifconfig removed_from_NIC

    By using the example in step 4, you would enter the following commands:

    # ifconfig hme1 inet plumb# ifconfig hme1 inet 1.2.3.4 -failover up group one# ifconfig hme1 addif 1.2.3.5 failover up# ifconfig hme1 addif 1.2.3.6 failover up

    Conguring the MultipathingConguration FileThe mu ltipathing /etc/default/mpathd conguration le contains threeparameters that you can adjust for your conguration requirements:

    4 FAILURE_DETECTION_TIME

    4 FAILBACK

    4 TRACK_INTERFACES_ONLY_WITH_GROUPS

    See Multipathing Conguration File on page 24 for a description of theseparameters.

    How to Congure the Multipathing CongurationFile1. Become superuser.

    2. Edit the /etc/default/mpathd and change the default value of one or moreof the three parameters using one or more of the following sub-steps.

    a. Type the new value for the FAILURE_DETECTION_TIME parameter.

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    FAILURE_DETECTION_TIME= n

    b. Type the new value for the FAILBACK parameter.

    FAILBACK=[yes | no]

    c. Type the new value for the TRACK_INTERFACES_ONLY_WITH_GROUPSparameter.

    TRACK_INTERFACES_ONLY_WITH_GROUPS=[yes | no]

    3. On a command line, type the following command.

    # pkill -HUP in.mpathd

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    Glossary

    This glossary contains only denitions of new terms found in this book and are notin the Global Glossary. For denitions of other terms, see the Global Glossary athttp://docs.sun.com:80/ab2/coll.417.1/GLOBALGLOSS/@Ab2TocView .

    failback The process of switching back network access to an interfacedetected as having been repaired.

    failover The process of switching network access from a failed interface to agood physical interface. Network access includes IPv4 unicast,mu lticast, and broadcast trafc, as well as IPv6 unicast an dmu lticast tra fc.

    failure detection The process of detecting when a NIC or the path from the NIC tosome layer 3 device starts operating correctly after a failure.

    IP link A communication facility or medium over which nodes cancommunicate at the link layer. The link layer is th e layerimmediately below IPv4/ IPv6. Examples include Ethernets (simpleor bridged) or ATM networks. One or more IPv4 subnet numbers/ prexes are assigned to an IP link. A subnet number/ prex can not

    be assigned to more than one IP link. In ATM LANE, an IP link is asingle em ulated LAN. When u sing ARP, the scope of the ARPprotocol is a single IP link.

    Network InterfaceCard (NIC)

    Network adapter that is either internal or a separate card that servesas an interface to a link.

    physical interface A n odes attachment to a link. This attachment is often implementedas a device driver plus a network adapter. Some network adapterscan hav e m ultiple p oints of attachment, for example, qfe. The usageof Network adapter in this document refers to a "Single Point of Attachment."

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    physical interfacegroup

    The set of physical interfaces on a system that are connected to thesame link. They are identied by assigning the same (non-null)character string name to all the physical interfaces in the group.

    physical interfacegroup name

    A name assigned to a physical interface that identies the group.The nam e is local to a system. Mu ltiple p hysical interfaces, sharingthe same group name, form a physical interface group.

    repair detection The process of detecting when a NIC or the path from the NIC tosome layer 3 device starts operating correctly after a failure.

    standby A p hysical interface that is not used to carry d ata trafc unlesssome other physical interface has failed.

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    Iifcong command

    deprecated attribute 18displaying multipathing group 35failover option 17group param eter 15, 22, 29, 36multipathing groups 15standby parameter 20, 33test parameter 29

    ifcong ether commandmultipathing 15

    in.mpathd daemon 12failback 25failure detection time 25multipathing 23probing rate 23probing targets 13standby interface 20

    IP link, multipathing 11IP network multipathing , see multipathingIPv4 test ad dress

    conguring 17, 29

    deprecated parameter 29IPv6 link-local add ress, multipathing 17IPv6 test ad dress

    conguring 17, 30

    Llink failures

    multipathing 14link-local address

    IPv6 test address 18multipathing 18

    load spreadingdenit ion 10

    Mmac addresses

    multipathing 15multipathing

    adding an interface from a group 35ATM 15components 11conguration le 24conguring a group with a hot standby

    interface 32

    conguring a standby interface 32conguring conguration le 40conguring interface group 27conguring IPv6 test address 30conguring test addresses 16creating a test group 31detached network adapters 22display group name 35display groups 34DR-detached 22dynamic reconguration 22enabling 14Ethernet 15failure detection 10, 12failure detection time 25features 10group names 14groups with multiple interfaces 14hostname le 18, 31, 33ifcong command 15ifcong ether command 15IP link 11

    IPv4creating a test group 33placing a standby interface in a

    g roup 34IPv6

    creating a test group 34placing a standby interface in a

    g roup 34link failures 14link-local add ress 18load spreading 10mac addresses 15moving interfaces from groups 36network interface 11physical interface 11physical interface group 11physical interface group name 11placing an interface in a test group 32preserving conguration across

    reboots 31, 33reboot-safe 22recovering a physical interface not present

    at system boot 38removing adapters from groups 22removing an interface from a group 35

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