Logical Interface Properties
This topic discusses how to configure various logical interface properties with examples.
Logical Interface Properties Overview
For a physical interface device to function, you must configure at least one logical interface on that device. For each logical interface, you must specify the protocol family that the interface supports. You can also configure other logical interface properties. These vary by Physical Interface Card (PIC) and encapsulation type, but include the IP address of the interface, and whether the interface supports multicast traffic, data-link connection identifiers (DLCIs), virtual channel identifiers (VCIs) and virtual path identifiers (VPIs), and traffic shaping.
To configure logical interface properties, include the statements at the following hierarchy levels:
[edit interfaces interface-name]
[edit logical-systems logical-system-name interfaces interface-name]
See Also
Specifying the Logical Interface Number
Each logical interface must have a logical unit number. The logical unit number corresponds to the logical unit part of the interface name. For more information, see Interface Naming Overview.
Point-to-Point Protocol (PPP), Cisco High-level Data Link Control (HDLC), and Ethernet circuit cross-connect (CCC) encapsulations support only a single logical interface, whose logical unit number must be 0. Frame Relay and ATM encapsulations support multiple logical interfaces, so you can configure one or more logical unit numbers.
You specify the logical unit number by including the unit
statement:
unit logical-unit-number { ... }
You can include this statement at the following hierarchy levels:
[edit interfaces interface-name]
[edit logical-systems logical-system-name interfaces interface-name]
The range of number available for the logical unit number varies for different interface types. See unit for current range values.
Adding a Logical Unit Description to the Configuration
You can include a text description of each logical unit in the
configuration file. Any descriptive text you include is displayed
in the output of the show interfaces
commands, and is also
exposed in the ifAlias
Management Information Base (MIB)
object. It has no impact on the interface’s configuration. To
add a text description, include the description
statement:
description text;
You can include this statement at the following hierarchy levels:
[edit interfaces interface-name unit logical-unit-number]
[edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number]
The description can be a single line of text. If the text contains spaces, enclose it in quotation marks.
You can configure the extended DHCP relay to include the interface description in the option 82 Agent Circuit ID suboption. See “Using DHCP Relay Agent Option 82 Information” in the Junos OS Subscriber Management and Services Library .
For information about describing physical interfaces, see Configuring Interface Description.
Configuring the Interface Bandwidth
By default, the Junos OS uses the physical interface’s
speed for the MIB-II object, ifSpeed
. You can configure
the logical unit to populate the ifSpeed
variable by configuring
a bandwidth value for the logical interface. The bandwidth
statement sets an informational-only parameter; you cannot adjust
the actual bandwidth of an interface with this statement.
We recommend that you be careful when setting this value.
Any interface bandwidth value that you configure using the bandwidth
statement affects how the interface cost is calculated for a dynamic
routing protocol, such as OSPF. By default, the interface cost for
a dynamic routing protocol is calculated using the following formula:
cost = reference-bandwidth/bandwidth,
where bandwidth is the physical interface speed. However, if
you specify a value for bandwidth using the bandwidth
statement,
that value is used to calculate the interface cost, rather than the
actual physical interface bandwidth.
To configure the bandwidth value for a logical interface, include
the bandwidth
statement:
bandwidth rate;
You can include this statement at the following hierarchy levels:
[edit interfaces interface-name unit logical-unit-number]
[edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number]
rate
is the peak rate, in bps
or cps. You can specify a value in bits per second either as a complete
decimal number or as a decimal number followed by the abbreviation k
(1000), m
(1,000,000), or g
(1,000,000,000).
You can also specify a value in cells per second by entering a decimal
number followed by the abbreviation c
; values expressed
in cells per second are converted to bits per second using the formula
1 cps = 384 bps. The value can be any positive
integer. The bandwidth
statement is valid for all logical
interfaces, except multilink interfaces.
Configuring Interface Encapsulation on Logical Interfaces
- Understanding Interface Encapsulation on Logical Interfaces
- Configuring the Encapsulation on a Logical Interface
- Displaying the Encapsulation on a Logical Interface
Understanding Interface Encapsulation on Logical Interfaces
You can configure an encapsulation on a logical interface, which is the encapsulation used within certain packet types.
The following restrictions apply to logical interface encapsulation:
With the atm-nlpid, atm-cisco-nlpid, and atm-vc-mux encapsulations, you can configure the inet family only.
With the CCC circuit encapsulations, you cannot configure a family on the logical interface.
A logical interface cannot have frame-relay-ccc encapsulation unless the physical device also has frame-relay-ccc encapsulation.
A logical interface cannot have frame-relay-tcc encapsulation unless the physical device also has frame-relay-tcc encapsulation. In addition, you must assign this logical interface a DLCI from 512 through 1022 and configure it as point-to-point.
A logical interface cannot have frame-relay-ether-type or frame-relay-ether-type-tcc encapsulation unless the physical interface has flexible-frame-relay encapsulation and is on an IQ or IQE PIC.
For frame-relay-ether-type-tcc encapsulation, you must assign this logical interface a DLCI from 512 through 1022.
For interfaces that carry IP version 6 (IPv6) traffic, you cannot configure ether-over-atm-llc encapsulation.
When you use ether-over-atm-llc encapsulation, you cannot configure multipoint interfaces.
A logical interface cannot have vlan-ccc or vlan-vpls encapsulation unless the physical device also has vlan-ccc or vlan-vpls encapsulation, respectively. In addition, you must assign this logical interface a VLAN ID from 512 through 1023; if the VLAN ID is 511 or lower, it is subject to the normal destination filter lookups in addition to source address filtering. For more information, see Configuring VLAN and Extended VLAN Encapsulation.
You can create an ATM cell-relay circuit by configuring an entire ATM physical device or an individual virtual circuit (VC). When you configure an entire device, only cell-relay encapsulation is allowed on the logical interfaces. For more information, see Configuring an ATM1 Cell-Relay Circuit Overview.
Configuring the Encapsulation on a Logical Interface
Generally, you configure an interface’s encapsulation
at the [edit interfaces interface-name]
hierarchy level. However, for some encapsulation types, such as
Frame Relay, ATM, and Ethernet virtual local area network (VLAN) encapsulations,
you can also configure the encapsulation type that is used inside
the Frame Relay, ATM, or VLAN circuit itself.
To configure encapsulation on a logical interface:
Displaying the Encapsulation on a Logical Interface
Purpose
To display the configured encapsulation and its associated
set options on a physical interface when the following are set at
the [edit interfaces interface-name]
or [edit logical-systems logical-system-name interfaces interface-name]
hierarchy
level:
interface-name—at-1/1/0
Encapsulation—
atm-ccc-cell-relay
Unit—120
Action
Run the show
command at the [edit interfaces interface-name]
hierarchy level.
[edit interfaces at-1/1/0] user@host# show encapsulation atm-ccc-cell-relay; unit 120 { encapsulation atm-ccc-cell-relay; }
Meaning
The configured encapsulation and its associated set options are displayed as expected.
Configuring Interface Encapsulation on PTX Series Packet Transport Routers
This topic describes how to configure interface encapsulation
on PTX Series Packet Transport Routers. Use the flexible-ethernet-services
configuration statement to configure different encapsulation for
different logical interfaces under a physical interface. With flexible
Ethernet services encapsulation, you can configure each logical interface
encapsulation without range restrictions for VLAN IDs.
Supported encapsulations for physical interfaces include:
flexible-ethernet-services
ethernet-ccc
ethernet-tcc
Supported encapsulations for logical interfaces include:
ethernet
vlan-ccc
vlan-tcc
PTX Series Packet Transport Routers do not support extended-vlan-cc
and extended-vlan-tcc
encapsulation
on logical interfaces. Instead, you can configure a tag protocol ID
(TPID) value of 0x9100 to achieve the same results.
To configure flexible Ethernet services encapsulation, include
the encapsulation flexible-ethernet-services
statement
at the [edit interfaces et-fpc/pic/port ]
hierarchy level.
For example:
interfaces { et-fpc/pic/port { vlan-tagging; encapsulation flexible-ethernet-services; unit 0 { vlan-id 1000; family inet { address 11.0.0.20/24; } } unit 1 { encapsulation vlan-ccc; vlan-id 1010; } unit 2 { encapsulation vlan-tcc; vlan-id 1020; family tcc { proxy { inet-address 11.0.2.160; } remote { inet-address 11.0.2.10; } } } } }
Configuring a Point-to-Point Connection
By default, all interfaces are assumed to be point-to-point connections. You must ensure that the maximum transmission unit (MTU) sizes on both sides of the connection are the same.
For all interfaces except aggregated Ethernet, Fast Ethernet,
and Gigabit Ethernet, you can explicitly configure an interface to
be a point-to-point connection by including the point-to-point
statement:
point-to-point;
You can include this statement at the following hierarchy levels:
[edit interfaces interface-name unit logical-unit-number]
[edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number]
Configuring a Multipoint Connection
By default, all interfaces are assumed to be point-to-point
connections. To configure an interface to be a multipoint connection,
include the multipoint
statement:
multipoint;
You can include this statement at the following hierarchy levels:
[edit interfaces interface-name unit logical-unit-number]
[edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number]
Configuring Dynamic Profiles for PPP
A dynamic profile acts as a template that enables you to create, update, or remove a configuration that includes attributes for client access (for example, interface or protocol) or service (for example, IGMP). Using these profiles you can consolidate all of the common attributes of a client (and eventually a group of clients) and apply the attributes simultaneously.
After they are created, the profiles reside in a profile library
on the router. You can then use the dynamic-profile
statement
to attach profiles to interfaces. To assign a dynamic profile to a
PPP interface, you can include the dynamic-profile
statement
at the [edit interfaces interface-name unit logical-unit-number ppp-options]
hierarchy level:
[edit interfaces interface-name unit logical-unit-number ppp-options] dynamic-profile profile-name;
To monitor the configuration, issue the show interfaces interface-name
command.
For information about dynamic profiles, see Dynamic Profiles Overview in the Junos Subscriber Access Configuration Guide.
For information about creating dynamic profiles, see Configuring a Basic Dynamic Profile in the Junos Subscriber Access Configuration Guide.
For information about assigning a dynamic profile to a PPP interface, see Attaching Dynamic Profiles to Static PPP Subscriber Interfaces in the Junos Subscriber Access Configuration Guide.
For information about using dynamic profiles to authenticate PPP subscribers, see Configuring Dynamic Authentication for PPP Subscribers.
Dynamic profiles for PPP subscribers are supported only on PPPoE interfaces for this release.
Configuring Accounting for the Logical Interface
- Accounting Profiles Overview
- Configuring Accounting for the Logical Interface
- Displaying Accounting Profile for the Logical Interface
Accounting Profiles Overview
Juniper Networks routers and switches can collect various kinds of data about traffic passing through the router and switch. You can set up one or more accounting profiles that specify some common characteristics of this data, including the following:
The fields used in the accounting records
The number of files that the router or switch retains before discarding, and the number of bytes per file
The polling period that the system uses to record the data
You configure the profiles and define a unique name for each
profile using statements at the [edit accounting-options]
hierarchy level. There are two types of accounting profiles: interface
profiles and filter profiles. You configure interface profiles by
including the interface-profile
statement at the [edit
accounting-options]
hierarchy level. You configure filter profiles
by including the filter-profile
statement at the [edit
accounting-options]
hierarchy level. For more information, see
the Junos OS Network Management Administration Guide for Routing Devices.
You apply filter profiles by including the accounting-profile
statement at the [edit firewall filter filter-name]
and [edit firewall family family filter filter-name]
hierarchy levels. For more information, see the Routing Policies, Firewall Filters, and Traffic Policers User Guide.
Configuring Accounting for the Logical Interface
Before you begin
You must configure a profile to collect error and statistic information for input and output packets on a particular logical interface. An accounting profile specifies what statistics should be collected and written to a log file. For more information on how to configure an accounting-data log file, see the Configuring Accounting-Data Log Files.
An interface profile specifies the information collected and written to a log file. You can configure a profile to collect error and statistic information for input and output packets on a particular logical interface.
See Also
Displaying Accounting Profile for the Logical Interface
Purpose
To display the configured accounting profile a particular
logical interface at the [edit accounting-options interface-profile profile-name]
hierarchy level:
interface-name—ge-1/0/1
Logical unit number—1
Interface profile —
if_profile
File name—
if_stats
Interval—15 minutes
Action
Run the
show
command at the[edit interfaces ge-1/0/1 unit 1]
hierarchy level.[edit interfaces ge-1/0/1 unit 1] accounting-profile if_profile;
Run the
show
command at the[edit accounting-options]
hierarchy level.interface-profile if_profile { interval 15; file if_stats { fields { input-bytes; output-bytes; input-packets; output-packets; input-errors; output-errors; } } }
Meaning
The configured accounting and its associated set options are displayed as expected.
Enabling or Disabling SNMP Notifications on Logical Interfaces
By default, Simple Network Management Protocol (SNMP) notifications
are sent when the state of an interface or a connection changes. To
explicitly enable these notifications on the logical interface, include
the traps
statement; to disable these notifications on
the logical interface, include the no-traps
statement:
(traps | no-traps);
You can include these statements at the following hierarchy levels:
[edit interfaces interface-name unit logical-unit-number]
[edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number]
Disabling a Logical Interface
You can unconfigure a logical interface, effectively disabling
that interface, without removing the logical interface configuration
statements from the configuration. To do this, include the disable
statement:
disable;
You can include this statement at the following hierarchy levels:
[edit interfaces interface-name unit logical-unit-number]
[edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number]
When an interface is disabled, a route (pointing to the reserved
target “REJECT
”) with the IP address of the
interface and a 32–bit subnet mask is installed in the routing
table. See Routing Protocols.
Example: Disabling a Logical Interface
Sample interface configuration:
[edit interfaces] user@host# show et-2/1/1 { vlan-tagging; encapsulation flexible-ethernet-services; unit 0 { vlan-id 1000; family inet { address 11.0.0.20/24; } } }
Disabling the interface:
[edit interfaces et-2/1/1 unit 0] user@host# set disable
Verifying the interface configuration:
[edit interfaces et-2/1/1] user@host# show disable; # Interface is marked as disabled. unit 0 { vlan-id 1000; family inet { address 11.0.0.20/24; } }