You can partition a single physical router into multiple
logical devices that perform independent routing tasks. Because logical
systems perform a subset of the tasks once handled by the physical
router, logical systems offer an effective way to maximize the use
of a single router.
Note:
In JUNOS Release 9.3 and later, the term logical system replaces logical router. All configuration statements, operational commands, show command outputs, error messages, log messages, and SNMP MIB objects
that contain the string logical-router or logical-routers are changed to logical-system and logical-systems, respectively.
Logical systems 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 systems within a single router
can handle the functions previously performed by several small routers.
The following are supported on logical systems:
BGP, IS-IS, LDP, OSPF, RIP, RIP next generation (RIPng),
RSVP, static routes, various multicast protocols, and IP version 4
(IPv4) and version 6 (IPv6) are supported at the [edit logical-systems
protocols] hierarchy level.
Basic MPLS for core provider router functionality is supported
at the [edit logical-systems protocols mpls] hierarchy level.
All policy-related statements available at the [edit
policy-options] hierarchy level are supported at the [edit
logical-systems policy-options] hierarchy level.
Most routing options statements available at the [edit
routing-options] hierarchy level are supported at the [edit
logical-systems routing-options] hierarchy level. Only the route-record statement is not supported at the [edit logical-systems
routing-options] hierarchy level.
Graceful Routing Engine switchover (GRES) is supported.
You can assign most interface types to a logical system,
including SONET/SDH 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 systems 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-systems logical-system-name protocols] hierarchy level. Rendezvous point (RP) and source
designated router (DR) functionality for multicast protocols within
a logical system is also supported.
The Bidirectional Forwarding Protocol (BFD) is supported.
The following restrictions apply to logical systems:
You can configure a maximum of 15 logical systems
on one physical router.
The router has only one configuration file, which contains
configuration information for the physical router and all associated
logical systems. Master users can access the full configuration. However,
logical system users can access only the portion of the configuration
related to their particular logical system.
All configuration commits performed by a logical system
user are treated as commit private. For more information
on the commit private command, see the JUNOS System Basics Configuration Guide.
If a logical system 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-system-name.core-tarball.number.tgz. Likewise, if
you issue the restart routing command in a logical system,
only the routing protocol process (rpd) for the logical system is
restarted.
If you configure trace options for a logical system, the
output log file is stored in the following location: /var/tmp/logical-system-name.
The following Physical Interface Cards (PICs) are not
supported with logical systems: Adaptive Services PIC, ES PIC, Monitoring
Services PIC, and Monitoring Services II PIC.
Sampling, port mirroring, IP Security (IPsec), and Generalized
MPLS (GMPLS) are not supported.
Label-switched path (LSP) ping and traceroute for autonomous
system (AS) number lookup are not supported.
If you configure multiple logical systems, you can configure
a VPLS routing instance only for the first logical system configured
at the [edit logical-systems logical-system-name routing-instances instance-name protocols vpls] hierarchy level.
A virtual router is not the same as a logical system. A virtual
router is a type of simplified routing instance that has a single
routing table. A logical system is a partition of a physical router
and can contain multiple routing instances and routing tables. For
example, a logical system can contain multiple virtual router routing
instances.
