Concept Guide

ip ospf dead-interval 60
ip ospf hello-interval 15
no shutdown
!
Loopback Interfaces
A Loopback interface is a virtual interface in which the software emulates an interface. Packets routed to it are processed locally.
Because this interface is not a physical interface, you can congure routing protocols on this interface to provide protocol stability. You can
place Loopback interfaces in default Layer 3 mode.
To congure, view, or delete a Loopback interface, use the following commands.
• Enter a number as the Loopback interface.
CONFIGURATION mode
interface loopback number
The range is from 0 to 16383.
• View Loopback interface congurations.
EXEC mode
show interface loopback number
• Delete a Loopback interface.
CONFIGURATION mode
no interface loopback number
Many of the same commands found in the physical interface are also found in the Loopback interfaces.
For more information, refer to Access Control Lists (ACLs).
Null Interfaces
The Null interface is another virtual interface. There is only one Null interface. It is always up, but no trac is transmitted through this
interface.
To enter INTERFACE mode of the Null interface, use the following command.
• Enter INTERFACE mode of the Null interface.
CONFIGURATION mode
interface null 0
The only congurable command in INTERFACE mode of the Null interface is the ip unreachable command.
VLAN Membership
A virtual LAN (VLANs) is a logical broadcast domain or logical grouping of interfaces in a LAN in which all data received is kept locally and
broadcast to all members of the group. In Layer 2 mode, VLANs move trac at wire speed and can span multiple devices. Dell Networking
OS supports up to 4093 port-based VLANs and one default VLAN, as specied in IEEE 802.1Q.
VLAN provide the following benets:
• Improved security because you can isolate groups of users into dierent VLANs.
• Ability to create one VLAN across multiple devices.
On an Aggregator in standalone mode, all ports are congured by default as members of all (4094) VLANs, including the default VLAN. All
VLANs operate in Layer 2 mode. You can recongure the VLAN membership for individual ports by using the vlan tagged or vlan
370
Interfaces