Brocade TurboIron 24X Series Configuration Guide - Manual (Page 513)

Brocade TurboIron 24X Series Configuration Guide 479
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Configuring IP parameters – Layer 3 Switches
Syntax: [no] ip irdp [broadcast | multicast] [holdtime <seconds>] [maxadvertinterval <seconds>]
[minadvertinterval <seconds>] [preference <number>]
The broadcast | multicast parameter specifies the packet type the Layer 3 Switch uses to send
Router Advertisement:
• broadcast – The Layer 3 Switch sends Router Advertisement as IP broadcasts. This is the
default.
• multicast – The Layer 3 Switch sends Router Advertisement as multicast packets addressed to
IP multicast group 224.0.0.1.
The holdtime <seconds> parameter specifies how long a host that receives a Router
Advertisement from the Layer 3 Switch should consider the advertisement to be valid. When a host
receives a new Router Advertisement message from the Layer 3 Switch, the host resets the hold
time for the Layer 3 Switch to the hold time specified in the new advertisement. If the hold time of
an advertisement expires, the host discards the advertisement, concluding that the router
interface that sent the advertisement is no longer available. The value must be greater than the
value of the maxadvertinterval parameter and cannot be greater than 9000. The default is three
times the value of the maxadvertinterval parameter.
The maxadvertinterval parameter specifies the maximum amount of time the Layer 3 Switch waits
between sending Router Advertisements. You can specify a value from 1 to the current value of the
holdtime parameter. The default is 600 seconds.
The minadvertinterval parameter specifies the minimum amount of time the Layer 3 Switch can
wait between sending Router Advertisements. The default is three-fourths (0.75) the value of the
maxadvertinterval parameter. If you change the maxadvertinterval parameter, the software
automatically adjusts the minadvertinterval parameter to be three-fourths the new value of the
maxadvertinterval parameter. If you want to override the automatically configured value, you can
specify an interval from 1 to the current value of the maxadvertinterval parameter.
The preference <number> parameter specifies the IRDP preference level of this Layer 3 Switch. If
a host receives Router Advertisements from multiple routers, the host selects the router interface
that sent the message with the highest interval as the host default gateway. The valid range is
0-4294967296 to 0-4294967295. The default is 0.
Configuring RARP
The Reverse Address Resolution Protocol (RARP) provides a simple mechanism for
directly-attached IP hosts to boot over the network. RARP allows an IP host that does not have a
means of storing its IP address across power cycles or software reloads to query a directly-attached
router for an IP address.
RARP is enabled by default. However, you must create a RARP entry for each host that will use the
Layer 3 Switch for booting. A RARP entry consists of the following information:
• The entry number – the entry sequence number in the RARP table.
• The MAC address of the boot client.
• The IP address you want the Layer 3 Switch to give to the client.
When a client sends a RARP broadcast requesting an IP address, the Layer 3 Switch responds to
the request by looking in the RARP table for an entry that contains the client MAC address:
• If the RARP table contains an entry for the client, the Layer 3 Switch sends a unicast response
to the client that contains the IP address associated with the client MAC address in the RARP
table.