Configuring Udp Broadcast And Ip Helper Parameters - Dell PowerConnect B-RX Configuration Manual

7
Configuring forwarding parameters
Syntax: [no] ip irdp [broadcast | multicast] [holdtime <seconds>] [maxadvertinterval <seconds>]
The broadcast | multicast parameter specifies the packet type the device uses to send Router
Advertisement.
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The holdtime <seconds> parameter specifies how long a host that receives a Router
Advertisement from the device should consider the advertisement to be valid. When a host
receives a new Router Advertisement message from the device, the host resets the hold time for
the device 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 device 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 device 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 the device. 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's default gateway. The valid range is
4294967296 to 4294967295. The default is 0.

Configuring UDP broadcast and IP helper parameters

Some applications rely on client requests sent as limited IP broadcasts addressed to the UDP's
application port. If a server for the application receives such a broadcast, the server can reply to
the client. Routers do not forward subnet directed broadcasts, so the client and server must be on
the same network for the broadcast to reach the server. If the client and server are on different
networks (on opposite sides of a router), the client's request cannot reach the server.
To configure the device to forward clients' requests to UDP application servers:
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Forwarding support for the following application ports is enabled by default:
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[minadvertinterval <seconds>] [preference <number>]
broadcast – The device sends Router Advertisement as IP broadcasts. This is the default.
multicast – The device sends Router Advertisement as multicast packets addressed to IP
multicast group 224.0.0.1.
Enable forwarding support for the UDP application port, if forwarding support is not already
enabled.
Configure a helper adders on the interface connected to the clients. Specify the helper address
to be the IP address of the application server or the subnet directed broadcast address for the
IP subnet the server is in. A helper address is associated with a specific interface and applies
only to client requests received on that interface. The device forwards client requests for any of
the application ports the device is enabled to forward to the helper address.
bootps (port 67)
BigIron RX Series Configuration Guide
53-1001810-01