JUNOS logical-router

Hmm… interesting:

esigpri@SRLAB1# help topic logical-routers overview
OverviewLogical routers perform a subset of the actions of a physical router and
have their own unique routing tables, interfaces, policies, and routing
instances. A set of logical routers within a single router can handle the
functions previously performed by several small routers.The following are supported on logical routers:
* Open Shortest Path First (OSPF), Intermediate System-to-Intermediate
System (IS-IS), Routing Information Protocol (RIP), RIP next
generation (RIPng), Border Gateway Protocol (BGP), Resource
Reservation Protocol (RSVP), Label Distribution Protocol (LDP), static
routes, various multicast protocols, and Internet Protocol version 4
(IPv4) and version 6 (IPv6) are supported at the [edit logical-routers
protocols] hierarchy level.

* Basic Multiprotocol Label Switching (MPLS) for core provider router
functionality is supported at the [edit logical-routers protocols
mpls] hierarchy level.

* All policy-related statements available at the [edit policy-options]
hierarchy level are supported at the [edit logical-routers
policy-options] hierarchy level.

* Most routing options statements available at the [edit
routing-options] hierarchy level are supported at the [edit
logical-routers routing-options] hierarchy level. Only the
route-record statement is not supported at the [edit logical-routers
routing-options] hierarchy level.

* You can assign most interface types to a logical router, including
SONET interfaces, Ethernet interfaces, Asynchronous Transfer Mode
(ATM) interfaces, ATM2 interfaces, Channelized Q Performance Processor
(QPP) interfaces, aggregated interfaces, link services interfaces, and
multilink services interfaces.

* Source class usage, destination class usage, unicast reverse path
forwarding, class of service, firewall filters, class-based
forwarding, and policy-based accounting work with logical routers when
you configure these features on the physical router.

* Multicast protocols, such as Protocol Independent Multicast (PIM) and
Distance Vector Multicast Routing Protocol (DVMRP) are supported at
the [edit logical-routers logical-router-name protocols] hierarchy

The following restrictions apply to logical routers:
* You can configure a maximum of 15 logical routers on one physical

* The router has only one configuration file, which contains
configuration information for the physical router and all associated
logical routers. Master users can access the full configuration.
However, logical router users can access only the portion of the
configuration related to their particular logical router.

* All configuration commits performed by a logical router user are
treated as commit private. For more information on the commit private
command, see the JUNOS System Basics Configuration Guide.

* If a logical router experiences an interruption of its routing
protocol process (rpd), the core dump output is saved in a file in the
following location:
/var/tmp/rpd_logical-router-name.core-tarball.number.tgz. Likewise, if
you issue the restart routing command in a logical router, only the
routing protocol process (rpd) for the logical router is restarted.

* If you configure trace options for a logical router, the output log
file is stored in the following location:

* The following Physical Interface Cards (PICs) are not supported with
logical routers: Adaptive Services PIC, ES PIC, Monitoring Services
PIC, and Monitoring Services II PIC.

* Graceful Routing Engine switchover, sampling, port mirroring, IP
Security (IPSec), and Generalized MPLS (GMPLS) are not supported.

* Rendezvous point functionality for multicast protocols within a
logical router is not supported.

* Label-switched path (LSP) ping and traceroute for autonomous system
(AS) number lookup are not supported.

Logical Routers and Virtual Routers

A virtual router is not the same as a logical router. A virtual router is
a type of simplified routing instance that has a single routing table. A
logical router is a partition of a physical router and can contain
multiple routing instances and routing tables. For example, a logical
router can contain multiple virtual router routing instances.


esigpri@SRLAB1# help reference logical-routers logical-routers

logical-routers logical-router-name;

Hierarchy Level


Release Information

Statement introduced before JUNOS Release 7.4.


Configure a logical router.


logical-router-name–Name of the logical router.

Usage Guidelines

See “Logical Router Configuration Guidelines”.

Required Privilege Level

routing–To view this statement in the configuration.
routing-control–To add this statement to the configuration.




  1. Wiwit Setiadi · September 20, 2007

    Wah master Sigit nich mainannya masih sama. Cuma beda dikit… digitnya. :)) peace.
    Ok. That’s all. Mudah2an betah aza di E.
    Salam sukses selalu.

  2. nico · September 21, 2007

    zenzen wakaranai yo..

  3. ericsonfp · September 21, 2007

    Aku tulis kanjinya Nic:
    Saya juga全然分からないよ!!

  4. brian · September 25, 2007

    ck ck…
    esigpri JA/EID

  5. shravani · October 31, 2007

    I hv few doubts abt junos….since u gave a very gud info abt logical routers…i thought u can help me….n here r my doubts…..
    can u please provide me a junos sample configuration file?also, can u please tell me which series of juniper router is most efficient in enterprise market?

  6. shravani · October 31, 2007

    also, wat is multiprotocol label switching?

  7. sigitp · November 1, 2007

    mpls is a new packet forwarding mechanism, it uses labels instead of destination ip address (impact: faster forwarding, more application can be applied within). for more detailed information, you can visit this link:

    sorry, I can not provide mine, for learning purposes juniper has this Knowledge Base site, you can find any configuration examples there:

  8. shravani · November 5, 2007

    thanks a lot….i dont need the sample file also….but a small doubt…suppose in netscreen ,if we do getconfig…we can see the output as
    set hostname hostname
    i could see two types of configurationsin junos….CLI and configure….but in the device,how do the output config look like…is it in
    [edit system]
    set host-name hostname
    or in the scope format like..
    host-name host-name

    hope u got my qn…..
    i m totally confused…help me out plz..!!

  9. sigitp · November 5, 2007

    the second format is displayed if we request show configuration on the device

    at first, i am also confused 🙂

  10. akila · March 31, 2008

    i have few doubts about junos can you please tel me how nat operation works and on which interface (whether nat operation will work only service interface ?)

  11. Prakash · April 9, 2008

    Is there any GUI for Juniper M10i routers?

  12. sigitp · April 9, 2008

    @ akila
    you can refer to http://rendo.info and contact him
    i am not fluently talk juniper 😀

    @ prakash
    yes, there is
    refer to:

  13. akila · April 11, 2008

    Thanks ..a lot.could please help me…is it telnet access is possible from the junos router…?

  14. A.Thirupathi · May 11, 2008

    Thanks a Lot

  15. A.Thirupathi · May 11, 2008

    Could U pls send me the JUNIPER Router Command.

  16. 孟 诗宇 · August 30, 2008

    akila, you need to enable telnet service by issusing:
    ‘set system services telnet’
    , and commit it.
    btw, you can’t telnet to a juniper router as root, create a super-user class account to telnet to the router, and root should always login to a router by ssh remotely.

  17. Uniorie · October 7, 2008

    Подскажите шооблончег под WordPress 2.6.2, чтобы был похож на ваш sigitp.wordpress.com.

    Заранее благодарю)

  18. akila · July 4, 2009

    nice post … i like it very much

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