Filter
Top Products
PowerConnect B-Series FCX Configuration Guide 833
53-1002266-01
Configuring IP parameters – Layer 3 Switches
26
• If you leave the feature 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 Layer 3 Switch periodically sends Router Advertisement messages out
the IP interfaces on which the feature is enabled. The messages advertise the Layer 3 Switch IP
addresses to directly attached hosts who listen for the messages. In addition, hosts can be
configured to query the Layer 3 Switch 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 on the Layer 3 Switch, the Layer 3 Switch responds to the Router Solicitation
messages. Some clients interpret this response to mean that the Layer 3 Switch is the default
gateway. If another router is actually the default gateway for these clients, leave IRDP disabled on
the Layer 3 Switch.
IRDP uses the following parameters. If you enable IRDP on individual ports instead of enabling the
feature globally, you can configure these parameters on an individual port basis:
• Packet type – The Layer 3 Switch 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
Layer 3 Switch sends the Router Advertisement messages every 450 – 600 seconds by
default. The time within this interval that the Layer 3 Switch 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 Layer 3 Switch 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 0-4294967296 to 0-4294967295.
The default is 0.
Enabling IRDP globally
To globally enable IRDP, enter the following command.
PowerConnect(config)# ip irdp
This command enables IRDP on the IP interfaces on all ports. Each port uses the default values for
the IRDP parameters. The parameters are not configurable when IRDP is globally enabled.