VLANs and Interfaces

VLANs and Interfaces

Quiz Pagehttps://networkdirection.net/labsandquizzes/quizzes/juniper-jncia/vlans-and-interfaces

Lab Pagehttps://networkdirection.net/labsandquizzes/labs/jncia-labs/vlans-and-interfaces


There are several acronyms for interface types and components:

  • IFD – Interface Physical Device
  • IFL – Interface Logical Device
  • IFF – Address Family
  • IFA – Address Entry

Common interface names are:

  • ge – Gigabit ethernet
  • xe – 10G ethernet
  • et – 100G ethernet
  • ae – aggregated ethernet (LAG/etherchannel)
  • vlan or irb – Logical interface based on VLAN

SFP’s can be of different speeds (eg, one may be 1G, and another may be 10G). So be aware that the interface names may change based on the SFP used.

The interface naming convention is type-x/y/z

  • Type is ge, xe, etc
  • x – FPC (aka linecard)
  • y – module or slot
  • z – port number

There are several names for management interfaces. Each platform may use different names. These include fxp0, em0, me0, and vme0. Some of these are physical, and others are virtual.

Some interfaces, such as pimd, pime, dsc, ipip, and gre, are special interfaces that are used for special purposes.

An unnumbered interface does not have an IP address. This helps conserve IP addresses.

All interfaces are configured with a unit. This contains logical interface information, like addressing. Sometimes this is used to create sub-interfaces. Physical properties (duplex, link speed, etc) are not configured in the unit.

Each unit may have one or more family. This is where the address is applied. For example, the inet family is for IPv4 addressing.

Addresses can be primary, preferred, or secondary. Primary addresses are used for locally sourced (broadcast or multicast) traffic, destined to a remote subnet. Preferred addresses are for locally sourced traffic to the local subnet.

Configuring voice ports means three main steps:

  • Configuring a voice VLAN
  • Configuring PoE
  • Configuring LLDP-MED

Junos supports regex during configuration.

Command Summary

Command Mode Description
show interfaces terse operational Get a simplified view of all interfaces on the system
show interfaces <extensive> operational Get interface statistics
set interfaces INTERFACE … configuration Configures an interface
set interfaces INTERFACE description configuration Adds a description to an interface
set interfaces INTERFACE unit NUMBER family inet address … configuration Configures an IPv4 address
set interfaces INTERFACE disable configuration Disables an interface
set vlans NAME vlan-id ID configuration Defines a VLAN
show vlans operational Shows a list of configured VLANs
set interfaces INTERFACE unit 0 family ethernet-switching interface-mode <access|trunk> configuration Sets a layer-2 port type (trunk port or access port)
set interfaces INTERFACE unit 0 family ethernet-switching vlan members VLAN configuration Adds VLANs to the port
set interfaces INTERFACE vlan-tagging configuration Enables VLAN tagging, which enables the use of units as subinterfaces
set poe interface all configuration Enables PoE on all interfaces
set protocols lldp-med interface all configuration Enables LLDP-MED on all interfaces
rename configuration Renames some configuration
deactivate configuration Deactivates any part of the config
copy configuration Copy some configuration from one place to another
replace configuration Replace some configuration
annotate configuration Adds annotations into the config, like comments in code

Additional References

Explanation of “ifd” and “ifl” indexes  https://kb.juniper.net/InfoCenter/index?page=content&id=KB2820

Router Interfaces Overview  https://www.juniper.net/documentation/en_US/junos/topics/concept/interfaces-interface-naming-overview.html

Performing Loopback Testing https://www.juniper.net/documentation/en_US/junos/topics/topic-map/ethernet-fast-and-gigabit-loopback-testing.html

Configuring Default, Primary, and Preferred Addresses and Interfaces https://www.juniper.net/documentation/en_US/junos/topics/task/configuration/interfaces-configuring-default-primary-and-preferred-addresses-and-interfaces.html

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