Brocade TurboIron 24X Series Configuration Guide - Manual (Page 515)

Brocade TurboIron 24X Series Configuration Guide 481
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Configuring IP parameters – Layer 3 Switches
The <number> parameter identifies the RARP entry number. You can specify an unused number
from 1 to the maximum number of RARP entries supported on the device. To determine the
maximum number of entries supported on the device, refer to the section
“Displaying and
modifying system parameter default settings” on page 265.
The <mac-addr> parameter specifies the MAC address of the RARP client.
The <ip-addr> parameter specifies the IP address the Layer 3 Switch will give the client in response
to the client RARP request.
Changing the maximum number of static RARP entries supported
The number of RARP entries the Layer 3 Switch supports depends on how much memory the Layer
3 Switch has. To determine how many RARP entries your Layer 3 Switch can have, display the
system default information using the procedure in the section
“Displaying and modifying system
parameter default settings” on page 265.
If your Layer 3 Switch allows you to increase the maximum number of RARP entries, you can use a
procedure in the same section to do so.
NOTE
You must save the configuration to the startup-config file and reload the software after changing the
RARP cache size to place the change into effect.
Configuring UDP broadcast and IP helper parameters
Some applications rely on client requests sent as limited IP broadcasts addressed to the UDP
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 request cannot reach the server.
You can configure the Layer 3 Switch to forward clients‘ requests to UDP application servers. To do
so:
• 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 Layer 3 Switch
forwards client requests for any of the application ports the Layer 3 Switch 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)