© Copyright IBM Corp. 2011 Chapter 2. Initial Setup 41
Loopback Interfaces
A loopback interface provides an IP address, but is not otherwise associated with a
physical port or network entity. Essentially, it is a virtual interface that is perceived as
being “always available” for higher-layer protocols to use and advertise to the
network, regardless of other connectivity.
Loopback interfaces improve switch access, increase reliability, security, and
provide greater flexibility in Layer 3 network designs. They can be used for many
different purposes, but are most commonly for management IP addresses, router
IDs for various protocols, and persistent peer IDs for neighbor relationships.
In IBM N/OS 6.8, loopback interfaces have been expanded for use with routing
protocols such as OSPF and BGP. Loopback interfaces can also be specified as the
source IP address for syslog, SNMP, RADIUS, TACACS+, NTP, and router IDs.
Loopback interfaces must be configured before they can be used in other features.
Up to five loopback interfaces are currently supported. They can be configured
using the following commands:
Using Loopback Interfaces for Source IP Addresses
The switch can use loopback interfaces to set the source IP addresses for a variety
of protocols. This assists in server security, as the server for each protocol can be
configured to accept protocol packets only from the expected loopback address
block. It may also make is easier to locate or process protocol information, since
packets have the source IP address of the loopback interface, rather than numerous
egress interfaces.
Configured loopback interfaces can be applied to the following protocols:
•
Syslogs
•
SNMP traps
•
RADIUS
•
TACACS+
•
NTP
Loopback Interface Limitation
• ARP is not supported. Loopback interfaces will ignore ARP requests.
• Loopback interfaces cannot be assigned to a VLAN.
RS G8000(config)# interface loopback <1-5>
RS G8000(config-ip-loopback)# [no] ip address <IPv4 address> <mask> enable
RS G8000(config-ip-loopback)# exit
RS G8000(config)# logging source-interface loopback <1-5>
RS G8000(config)# snmp-server trap-source loopback <1-5>
RS G8000(config)# ip radius source-interface loopback <1-5>
RS G8000(config)# ip tacacs source-interface loopback <1-5>
RS G8000(config)# ntp source loopback <1-5>
To Next Page
Loading...
Need help?
General
