Dell BigIron RX Series, Configuration Manual

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216 BigIron RX Series Configuration Guide
53-1002253-01
Configuring forwarding parameters
7
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:
•
Enable forwarding support for the UDP application port, if forwarding support is not already
enabled.
•
Configure a helper address 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.
Forwarding support for the following application ports is enabled by default:
•
bootps (port 67)
•
dns (port 53)
•
tftp (port 69)
•
time (port 37)
•
netbios-ns (port 137)
•
netbios-dgm (port 138)
•
tacacs (port 65)
NOTE
The application names are the names for these applications that the device recognizes, and might
not match the names for these applications on some third-party devices. The numbers listed in
parentheses are the UDP port numbers for the applications. The numbers come from RFC 1340.