IP Forwarding
Configuring IP
page 15-10
OmniSwitch AOS Release 7 Network Configuration Guide
June 2013
Configuring a Loopback0 Interface
Loopback0 is the name assigned to an IP interface to identify a consistent address for network
management purposes. The Loopback0 interface is not bound to any VLAN, so it always remains
operationally active. If there are no active ports in the VLAN, all IP interface associated with that VLAN
are not active. In addition, the Loopback0 interface provides a unique IP address for the switch that is
easily identifiable to network management applications.
This type of interface is created in the same manner as all other IP interfaces, using the
command. To identify a Loopback0 interface, enter
Loopback0
for the interface name. For example, the
following command creates the Loopback0 interface with an IP address of 10.11.4.1:
-> ip interface Loopback0 address 10.11.4.1
Note the following when configuring the Loopback0 interface:
•
The interface name, “Loopback0”, is case sensitive.
•
The Loopback0 interface is always active and available.
•
Only one Loopback0 interface per switch is allowed.
•
Loopback0 address cannot be modified once it is configured.
•
Creating this interface does
not
deduct from the total number of IP interfaces allowed per VLAN or
switch.
•
To change the address, remove the interface using the
no ip interface Loopback0
command and
readd it with the new address.
Loopback0 Address Advertisement
The Loopback0 IP interface address is automatically advertised by the IGP protocols RIP and OSPF when
the interface is created. There is no additional configuration necessary to trigger advertisement with these
protocols.
Note the following regarding Loopback0 advertisement:
•
RIP advertises the host route to the Loopback0 IP interface as a redistributed (directhost) route.
•
OSPF advertises the host route to the Loopback0 IP interface in its Router-LSAs (as a Stub link) as an
internal route into all its configured areas.
Configuring a BGP Peer Session with Loopback0
It is possible to create BGP peers using the Loopback0 IP interface address of the peering router and
binding the source (that is, outgoing IP interface for the TCP connection) to its own configured Loopback0
interface. The Loopback0 IP interface address can be used for both Internal and External BGP peer
sessions. For EBGP sessions, if the external peer router is multiple hops away, the
ebgp-multihop
parameter can be used.
The following example command configures a BGP peering session using a Loopback0 IP interface
address:
-> ip bgp neighbor 2.2.2.2 update-source Loopback0
See the
OmniSwitch AOS Release 7 Advanced Routing Configuration Guide
for more information.