Enabling IRDP on an individual port

To enable IRDP on an individual interface and change IRDP parameters, enter commands such as the following. 

device(config)# interface ethernet 1/1/3
device(config-if-1/1/3)# ip irdp maxadvertinterval 400

This example shows how to enable IRDP on a specific port and change the maximum advertisement interval for Router Advertisement messages to 400 seconds.

NOTE
To enable IRDP on individual ports, you must leave the feature globally disabled.

Syntax: [no] ip irdp { broadcast | multicast } [ holdtime seconds ] [ maxadvertinterval seconds ] [ minadvertinterval seconds ] [ preference number ]

The broadcast and multicast parameters specify 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 from 0 to 4294967296. The default is 0.

Parent topic: IRDP parameters