Reverse address resolution protocol configuration, How rarp differs from bootp and dhcp, Disabling rarp – Brocade Communications Systems Layer 3 Routing Configuration ICX 6650 User Manual
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Brocade ICX 6650 Layer 3 Routing Configuration Guide
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Configuring IP parameters – Layer 3 Switches
Reverse Address Resolution Protocol configuration
The Reverse Address Resolution Protocol (RARP) provides a simple mechanism for
directly-attached IP hosts to boot over the network. RARP allows an IP host that does not have a
means of storing its IP address across power cycles or software reloads to query a directly-attached
router for an IP address.
RARP is enabled by default. However, you must create a RARP entry for each host that will use the
Layer 3 Switch for booting. A RARP entry consists of the following information:
•
The entry number – the entry sequence number in the RARP table.
•
The MAC address of the boot client.
•
The IP address you want the Layer 3 Switch to give to the client.
When a client sends a RARP broadcast requesting an IP address, the Layer 3 Switch responds to
the request by looking in the RARP table for an entry that contains the client MAC address:
•
If the RARP table contains an entry for the client, the Layer 3 Switch sends a unicast response
to the client that contains the IP address associated with the client MAC address in the RARP
table.
•
If the RARP table does not contain an entry for the client, the Layer 3 Switch silently discards
the RARP request and does not reply to the client.
How RARP differs from BootP and DHCP
RARP and BootP/DHCP are different methods for providing IP addresses to IP hosts when they
boot. These methods differ in the following ways:
•
Location of configured host addresses:
-
RARP requires static configuration of the host IP addresses on the Layer 3 Switch. The
Layer 3 Switch replies directly to a host request by sending an IP address you have
configured in the RARP table.
-
The Layer 3 Switch forwards BootP and DHCP requests to a third-party BootP/DHCP server
that contains the IP addresses and other host configuration information.
•
Connection of host to boot source (Layer 3 Switch or BootP/DHCP server):
-
RARP requires the IP host to be directly attached to the Layer 3 Switch.
-
An IP host and the BootP/DHCP server can be on different networks and on different
routers, so long as the routers are configured to forward (“help”) the host boot request to
the boot server.
-
You can centrally configure other host parameters on the BootP/DHCP server, in addition
to the IP address, and supply those parameters to the host along with its IP address.
To configure the Layer 3 Switch to forward BootP/DHCP requests when boot clients and the boot
servers are on different subnets on different Layer 3 Switch interfaces, refer to
relay parameter configuration”
Disabling RARP
RARP is enabled by default. To disable RARP, enter the following command at the global CONFIG
level.
Brocade(config)# no ip rarp