Brocade Communications Systems FastIron SX 1600, Configuration Manual, Page: 80 / 593

To assign a static IP RARP entry for static routes on a Brocade router, enter a command such as the following.
device(config)# rarp 1 0000.0054.2348 10.53.4.2
This command creates a RARP entry for a client with MAC address 0000.0054.2348. When the Layer 3 switch receives a RARP
request from this client, the Layer 3 switch replies to the request by sending IP address 192.53.4.2 to the client.
Syntax: rap number mac-addr ip-addr
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" in the
FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide .
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
system parameter default values" in the
FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide .
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:
• dns (port 53)
• tftp (port 69)
• time (port 37)
• tacacs (port 65)
Configuring IP parameters - Layer 3 switches
FastIron Ethernet Switch Layer 3 Routing
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