BLADE OS 5.1 Release Notes
12
BMD00098, December 2009
Internal Loopback Interface
BLADEOS 5.1 now supports up to five loopback interfaces.
A loopback interface is an interface which is assigned an IP address, but is not associated with any
particular physical port. The loopback interface is thus always available for higher layer protocols
to use and advertise to the general network, regardless of which specific ports are in operation.
Loopback interfaces can be of benefit in a number of protocols, improving access to a switch, as
well as increasing its reliability, security, and scalability. In addition, loopback interfaces can add
flexibility and simplify management, information gathering, and filtering.
One example of this increased reliability is for OSPF to use a loopback interface in combination
with host routes to advertise an interface route which will be available regardless of the status of
individual physical links. This provides a higher probability that the routing traffic will be received
and subsequently forwarded.
Further reliability and performance could be provided by configuring parallel BGP paths to a
loopback interface on a peer device, which would result in improved load sharing.
Access and security can be improved through filtering. Incoming traffic can be filtered by rules that
specify loopback interfaces as the only acceptable destination addresses.
Information gathering and filtering as well as management can potentially be simplified if protocols
such as SNMP use loopback interfaces for receiving and sending trap and log type information.
The Loopback Interface configuration menu is accessed using the following CLI command:
Rate Limiting
BLADEOS 5.1 now supports traffic rate limits for packets broadcast, multicast, and unknown
unicast packets. For each port, the maximum number of packets permitted per second for each
packet type can be specified. The following commands have been added to the Port menu
(
/cfg/port
<x>
) to support rate limiting:
brate
<value>
|dis
Broadcast limit, 0 to 262143 packets per second, or no limit.
mrate
<value>
|dis
Multicast limit, 0 to 262143 packets per second, or no limit.
drate
<value>
|dis
Unknown unicast limit, 0 to 262143 packets per second, or no limit.
# /cfg/l3/loopif
<loopback interface number (1-5)>
