Logical Interfaces Assigned to a Logical System

Logical interfaces assigned to a logical system are described in the following sections:

Logical Systems Overview

With JUNOS Software, you can partition a single physical system into multiple logical systems that perform independent routing tasks. Each logical system has its own unique routing tables, interfaces, policies, and routing instances. A set of logical systems within a single router can handle the functions otherwise performed by several small routers, offering an effective way to maximize the use of a single routing or switching platform.

Note: A virtual router does not have the same capabilities as a logical system. A virtual router is a type of simplified routing instance that has a single routing table. By contrast, a logical system is a partition of the main router and can contain multiple virtual router routing instances. As a result, these two entities are not equivalent.

For additional information about logical system configuration and administration, see the JUNOS Feature Guide and the JUNOS System Basics Configuration Guide.

For additional information about logical system interface configuration, see the JUNOS Network Interfaces Configuration Guide and the JUNOS Services Interfaces Configuration Guide.

Logical System Configuration Overview

Configuring a logical system consists of a sequence of tasks, some of which can only be performed by you as the master administrator—a JUNOS user with superuser configuration and verification privileges on the router. Other tasks can be performed by a logical system administrator—a JUNOS user that you have assigned to the logical system and is thereby granted configuration and verification privileges for only the logical systems to which that user is assigned. The following sequence summarizes the steps required to configure a logical system:

To configure a logical system, you (as the master administrator) first specify a logical-system-name at the [edit logical-systems] hierarchy level.
For any logical system, you (as the master administrator) can assign one or more logical system administrators. To configure logical system administrators, include the logical-system logical-system-name statement at the [edit system login class class-name] hierarchy level.
The minimum configuration of a logical system includes one or more logical interfaces. Before any logical interfaces can be assigned to a logical system, though, you (as the master administrator) must configure physical interface properties (such as encapsulation types and interfaces-related options) on the main router. To configure physical interface properties on the main router, include the physical interface statements at the [edit interfaces interface-name] hierarchy level.
After the physical interface properties are configured on the main router, logical system configurations can be completed by assigning one or more logical interfaces to each logical system. For any logical system, either you or a logical system administrator of that logical system can assign logical interfaces. To configure, include the unit statement at the [edit logical-systems logical-system-name] hierarchy level.
Note: After you assign a logical interface to a logical system, it is considered part of the logical system. As such, any logical interface can be assigned to only one logical system.

For additional information about logical system configuration and administration, see the JUNOS Feature Guide and the JUNOS System Basics Configuration Guide.

For additional information about logical system interface configuration, see the JUNOS Network Interfaces Configuration Guide and the JUNOS Services Interfaces Configuration Guide.

Scope of Logical System Administration

Logical system administrators are confined to the context of the logical systems to which they are assigned. Any global configuration statements are restricted from them, and command output is restricted to the context to which the logical system administrators are assigned.

For JUNOS Software Release 9.1 and later, when a physical interface is specified within a logical system context, the show interfaces command output only displays information about the logical interfaces assigned to that logical system.

From within the context of a logical system (which you can select from the main router context by using the set cli logical-systems logical-system-name command), the show interfaces command output is limited to the resources assigned to the logical system:

The physical interfaces are listed by name, but no statistics are displayed.
Only the logical interfaces assigned to the logical system are listed, with statistics displayed.
None of the special, system-generated logical interfaces with logical unit number 32767 are listed.

At the main router level (to which you can return from the logical system context by using the clear cli logical system command), the show interfaces command output displays statistics for all interfaces configured on the router:

Statistics are displayed for all physical interfaces.
Statistics are displayed for all logical interfaces.
Statistics are displayed for all system-generated logical interfaces with logical unit number 32767.

Example: show interfaces terse

Consider a main router for which you have configured the physical interface at-0/0/0 with ATM-specific physical interface properties and configured the physical interface with a logical interface at logical unit 0. You have also configured logical system ls1 and assigned a logical system administrator for this logical system. The logical system administrator has assigned the logical interface at-0/0/0.0 to logical system ls1. The configuration is as follows:

logical-systems {ls1 {interfaces {at-0/0/0 {unit 0 {encapsulation atm-ccc-cell-relay;vpi 0;}}}protocols {mpls {label-switched-path base_config_r4r1_lsp {to 10.255.65.65;}interface all;}connections {remote-interface-switch base_config_vp_mode_connection {interface at-0/0/0.0;transmit-lsp base_config_r1r4_lsp; receive-lsp base_config_r4r1_lsp;}}}}}chassis {fpc 0 {pic 0 {atm-l2circuit-mode {cell;}}}}interfaces {at-0/0/0 {atm-options {pic-type atm2;promiscuous-mode {vpi 0;}}inactive: unit 0 {encapsulation atm-ccc-cell-relay;vpi 0;}}}protocols {mpls {interface all;}isis {disable;interface all {level 1 disable;level 2 metric 10;}interface fxp0.0 {disable;}}ospf {reference-bandwidth 4g;area 0.0.0.0 {interface all;interface fxp0.0 {disable;}}}}

Within the context of a logical system, logical system administration is confined to the resources assigned to that logical system.

The following example shows the output of the show interfaces terse command when you (as the master administrator) issue the command from the context of the main router:

user@host> show interfaces terse at-0/0/0

Interface               Admin Link Proto    Local                 Remote
at-0/0/0                up    up  
at-0/0/0.0              up    up   ccc     
at-0/0/0.32767          up    up

The physical interface name at-0/0/0 is reported, followed by all requested information (in the case of the show interfaces terse command, the Admin and Link states) about the physical interface.

The logical interface name at-0/0/0.0 is reported, followed by all requested information.

The output also displays all requested information about the special, system-generated logical interface at-0/0/0.32767, which the JUNOS Software uses for handling traffic that is not part of the interface. In the case of the ATM interface at-0/0/0, which is configured for cell-relay promiscuous virtual path identifier (VPI) mode, the system-generated logical interface at-0/0/0.32767 is used to track statistics associated with system-generated traffic, such as Operation, Administration, and Management (OAM) F4 cell flows.

Note: The show interfaces extensive command output displays the individual channel statistics associated with the special .32767 logical interface, but only when the command is issued from the context of the main router.

The following example shows how you can place yourself into the context of logical system ls1:
user@host> set cli logical-system ls1
```
Logical system: ls1
```
user@host:lst1>
The following example shows the output of the show interfaces terse operational command when you (as the master administrator) issue it from the context of logical system ls1 or when it is issued by a logical system administrator for the logical system ls1:
user@host:ls1> show interfaces terse at-0/0/0
```
Interface               Admin Link Proto    Local                 Remote
at-0/0/0               
at-0/0/0.0              up    up   ccc     
```
The physical interface name at-0/0/0 is reported, but any additional details about the physical interface (in the case of the show interfaces terse command, the Admin and Link states) are not displayed. The system-generated logical interface at-0/0/0.32767 is not reported at all.
The following example shows how you can move from the context of the logical system ls1 back to the context of the main router:
user@host:ls1> clear cli logical-system
```
Cleared default logical system
```
user@host>

For more logical system configuration examples, including verification of proper operation and verification performed by logical system administrators, see the JUNOS Feature Guide.