Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 848)

818 Multi-Service IronWare Switching Configuration Guide
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Configuring IP load sharing
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• multicast – The Brocade device 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 Brocade device should consider the advertisement to be valid. When a host receives a
new Router Advertisement message from the Brocade device, the host resets the hold time for the
Brocade 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 Brocade 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 Brocade 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 Brocade 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 Brocade device to forward client requests to UDP application servers:
• 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 Brocade device forwards client requests
for any of the application ports the Brocade 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)