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 Diers from BootP and DHCP
RARP and BootP and DHCP are
dierent methods for providing IP addresses to IP hosts when they boot. These methods dier in the
following ways:
• Location of congured host addresses:
– RARP requires static conguration 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 congured 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 conguration 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 dierent networks and on dierent routers, so long as the routers are
congured to forward ("help") the host boot request to the boot server.
– You can centrally congure 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 congure the Layer 3 switch to forward BootP/DHCP requests when boot clients and the boot servers are on dierent subnets on
dierent Layer 3 switch interfaces, refer to BootP and DHCP relay parameter conguration on page 82.
Disabling RARP
RARP is enabled by default. To disable RARP, enter the following command at the global CONFIG level.
device(config)# no ip rarp
Syntax: [no] ip rarp
To re-enable RARP, enter the following command.
device(config)# ip rarp
Creating static RARP entries
You must
congure the RARP entries for the RARP table. The Layer 3 switch can send an IP address in reply to a client RARP request
only if create a RARP entry for that client.
Conguring IP parameters - Layer 3 switches
FastIron Ethernet Switch Layer 3 Routing
53-1003627-04 79
To Next Page
Loading...
Need help?
General
