Alcatel-Lucent 6850-48 Guida Di Rete

RDP Overview

Configuring RDP

page 29-6

OmniSwitch AOS Release 6 Network Configuration Guide

An RDP interface is created by enabling RDP on a VLAN router IP address. Once enabled, the RDP inter-
face becomes active and joins the all-routers IP multicast group (224.0.0.2). The interface then transmits 
three initial router advertisement messages at random intervals that are no greater than 16 seconds apart. 
This process occurs upon activation to increase the likelihood that end hosts will quickly discover this 
router.

After an RDP interface becomes active and transmits its initial advertisements, subsequent advertisements 
are transmitted at random intervals that fall between a configurable range of time. This range of time is 
defined by specifying a maximum and minimum advertisement interval value. See 

 for more information. Because advertisements are transmitted at random 

intervals, the risk of system overload is reduced as advertisements from other routers on the same link are 
not likely to transmit at the same time.

It is important to note that advertisements are only transmitted on RDP interfaces if the following condi-
tions are met:

• The RDP global status is enabled on the switch.

• An IP interface exists and is in the enabled state.

• An RDP interface exists and is in the enabled state.

• Whether VRRP is disabled or enabled, there is one or more Master IP addresses for the VLAN. If 

VRRP is enabled and if there are no Masters IP addresses, router advertisements are not sent on the 
VLAN. (See 

 for more information.)

The router advertisement is a multicast packet sent to the all-systems IP multicast group (224.0.0.1) or the 
broadcast address. If VRRP is enabled, the message should be filled with IP addresses obtained from 
VRRP Master IP address list; otherwise the IP address of the IP router interface is used.

Note that RDP is not recommended for detecting neighboring router failures, referred to as black holes, in 
the network. However, it is possible to use RDP as a supplement for black hole detection by setting RDP 
interface advertisement interval and lifetime values to values lower than the default values for these 
parameters. See 

 for more information.