Brocade BigIron RX Series Configuration Guide - Manual (Page 294)

216 BigIron RX Series Configuration Guide
53-1002484-04
Configuring forwarding parameters
7
Configuring IRDP
The device uses ICMP Router Discovery Protocol (IRDP) to advertise the IP addresses of its router
interfaces to directly attached hosts. IRDP is disabled by default. You can enable it globally or on
individual port:
• If you enable IRDP globally, all ports use the default values for the IRDP parameters.
• If you leave IRDP disabled globally but enable it on individual ports, you also can configure the
IRDP parameters on an individual port basis.
NOTE
You can configure IRDP parameters only an individual port basis. To do so, IRDP must be disabled
globally and enabled only on individual ports. You cannot configure IRDP parameters if the feature
is globally enabled.
When IRDP is enabled, the device periodically sends Router Advertisement messages out the IP
interfaces on which the feature is enabled. The messages advertise the device’s IP addresses to
directly attached hosts who listen for the messages. In addition, hosts can be configured to query
the device for the information by sending Router Solicitation messages.
Some types of hosts use the Router Solicitation messages to discover their default gateway. When
IRDP is enabled, the device responds to the Router Solicitation messages. Some clients interpret
this response to mean that the device is the default gateway. If another router is actually the
default gateway for these clients, leave IRDP disabled on the device.
IRDP uses the following parameters. If you enable IRDP on individual ports rather than globally,
you can configure these parameters on an individual port basis using:
• Packet type – The device can send Router Advertisement messages as IP broadcasts or as IP
multicasts addressed to IP multicast group 224.0.0.1. The packet type is IP broadcast.
• Maximum message interval and minimum message interval – When IRDP is enabled, the
device sends the Router Advertisement messages every 450 – 600 seconds by default. The
time within this interval that the device selects is random for each message and is not affected
by traffic loads or other network factors. The random interval minimizes the probability that a
host will receive Router Advertisement messages from other routers at the same time. The
interval on each IRDP-enabled device interface is independent of the interval on other
IRDP-enabled interfaces. The default maximum message interval is 600 seconds. The default
minimum message interval is 450 seconds.
• Hold time – Each Router Advertisement message contains a hold time value. This value
specifies the maximum amount of time the host should consider an advertisement to be valid
until a newer advertisement arrives. When a new advertisement arrives, the hold time is reset.
The hold time is always longer than the maximum advertisement interval. Therefore, if the
hold time for an advertisement expires, the host can reasonably conclude that the router
interface that sent the advertisement is no longer available. The default hold time is three
times the maximum message interval.
• Preference – If a host receives multiple Router Advertisement messages from different
routers, the host selects the router that sent the message with the highest preference as the
default gateway. The preference can be a number from 4294967296 to 4294967295. The
default is 0.
Enabling IRDP globally
To globally enable IRDP, enter the following command.