Interfaces type on Juniper devices

In this lesson, I will discuss about the different types of interfaces that are available on Juniper devices. You may have seen that when we were doing LABs until now that many different interfaces were shown when we do the command “show interface terse” from the operational mode.

In fact, Juniper has 5 different interfaces types:

  • Management: to manage the Junos device (such as fxp0, me0)
  • Internal: connect the control plane and forwarding plane (fxp1, em0)
  • Network: connect the Junos device to other network devices (ethernet, ATM, T1, SONET)
  • Services: Encryption, Encapsulation, Tunneling, link services (es, gr, IP, lsq, st, tap)
  • Loopback: lo0 which is hardware independent

Those are the 5 different types of interfaces that you may see in the Juniper devices.

On Juniper, you can go to the physical interface level, and from there you can do things like changing the speed, making it duplex and so on.

There is also a logical interface where it is used to set an IPv4 or IPv6 address.

Let me show you what you can do on the physical interface as an example:

[edit interfaces ge-0/0/0]

root@R1# set ?

Possible completions:

accounting-profile   Accounting profile name

+ apply-groups         Groups from which to inherit configuration data

+ apply-groups-except  Don’t inherit configuration data from these groups

> auto-configure       Auto configuration

description          Text description of interface

disable              Disable this interface

encapsulation        Physical link-layer encapsulation

> esi                  ESI configuration of multi-homed interface

flexible-vlan-tagging  Support for no tagging, or single and double 802.1q VLAN tagging

> forwarding-class-accounting  Configure Forwarding-class-accounting parameters

> gigether-options     Gigabit Ethernet interface-specific options

gratuitous-arp-reply  Enable gratuitous ARP reply

> hierarchical-scheduler  Enable hierarchical scheduling

> hold-time            Hold time for link up and link down

interface-transmit-statistics  Interface statistics based on the transmitted packets

> layer2-policer       Layer2 policing for interface

link-mode            Link operational mode

mac                  Hardware MAC address

mtu                  Maximum transmit packet size (256..9192)

> multi-chassis-protection  Inter-Chassis protection configuration

—(more 55%)—

> multi-chassis-protection  Inter-Chassis protection configuration

native-vlan-id       Virtual LAN identifier for untagged frames (0..4094)

no-gratuitous-arp-reply  Don’t enable gratuitous ARP reply

no-gratuitous-arp-request  Ignore gratuitous ARP request

no-per-unit-scheduler  Don’t enable subunit queuing on Frame Relay or VLAN IQ interface

no-traps             Don’t enable SNMP notifications on state changes

oam-on-svlan         Propagate SVLAN OAM state to CVLANs

> optics-options       Optics options

> otn-options          Optical Transmission Network interface-specific options

passive-monitor-mode  Use interface to tap packets from another router

per-unit-scheduler   Enable subunit queuing on Frame Relay or VLAN IQ interface

speed                Link speed

stacked-vlan-tagging  Stacked 802.1q VLAN tagging support

> traceoptions         Interface trace options

traps                Enable SNMP notifications on state changes

> unit                 Logical interface

vlan-tagging         802.1q VLAN tagging support

vlan-vci-tagging     CCC for VLAN Q-in-Q and ATM VPI/VCI interworking

As highlighted, you can disable the interface, change the speed, and do much more things.

If you go to the logical interface, then you can set an IP address on the interface. To go to the logical interface you have to go to the following:

[edit interfaces ge-0/0/0]

root@R1# edit unit 0 family inet

[edit interfaces ge-0/0/0 unit 0 family inet]

root@R1# set address

[edit interfaces ge-0/0/0 unit 0 family inet]


By going to unit 0, you are in the logical interface, then you choose family inet meaning that you want to configure IPv4.

This is all what I wanted to explain in this lesson, hope you enjoyed it and see you in the upcoming one.

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