Brocade Virtual ADX Switch and Router Guide (Supporting ADX v03.1.00) - Manual (Page 97)

Brocade Virtual ADX Switch and Router Guide 83
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Configuring IP parameters
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• netbios-ns (port 137)
• ntp (port 123)
• tacacs (port 65)
• talk (port 517)
• time (port 37)
• tftp (port 69)
In addition, you can specify any UDP application by using the application’s UDP port number.
The udp-port-num parameter specifies the UDP application port number. If the application you
want to enable is not listed above, enter the application port number. You also can list the port
number for any of the applications listed above.
Configuring an IP helper address
To forward a client’s broadcast request for a UDP application when the client and server are on
different networks, you must configure a helper address on the interface connected to the client.
Specify the server’s IP address or the subnet directed broadcast address of the IP subnet the
server is in as the helper address.
You can configure up to 16 helper addresses on each interface. You can configure a helper address
on an Ethernet port or a virtual interface. To configure a helper address, use the following method.
To configure a helper address on interface 2 on chassis module 1, enter the following commands.
Virtual ADX(config)# interface e 2
Virtual ADX(config-if-2)# ip helper-address 1 10.95.7.6
The commands in this example change the CLI to the configuration level for port 1/2, then add a
helper address for server 10.95.7.6 to the port. If the port receives a client request for any of the
applications that the Virtual ADX is enabled to forward, the Virtual ADX forwards the client’s request
to the server.
Syntax: ip helper-address num ip-addr
The num parameter specifies the helper address number and can be from 1 – 16.
The ip-addr command specifies the server’s IP address or the subnet directed broadcast address
of the IP subnet the server is in.
Configuring BootP/DHCP forwarding parameters
A host on an IP network can use BootP/DHCP to obtain its IP address from a BootP/DHCP server.
To obtain the address, the client sends a BootP/DHCP request. The request is a subnet directed
broadcast and is addressed to UDP port 67. A limited IP broadcast is addressed to IP address
255.255.255.255 and is not forwarded by the Virtual ADX or other IP routers.
When the BootP/DHCP client and server are on the same network, the server receives the
broadcast request and replies to the client. However, when the client and server are on different
networks, the server does not receive the client’s request, because the Virtual ADX does not
forward the request.
You can configure the Virtual ADX to forward BootP/DHCP requests. To do so, configure a helper
address on the interface that receives the client requests, and specify the BootP/DHCP server’s IP
address as the address you are helping the BootP/DHCP requests to reach. Instead of the server’s
IP address, you can specify the subnet directed broadcast address of the IP subnet the server is in.