12-22-2010 10:57 AM
I’m having a problem configuring a Bootp server to run off of the RX-8 core router.
If I configure the Bootp server and plug it into a Fesx424 edge switch with a PC on the same switch and on the same Vlan (70) the BootP process works fine.
If I configure the BootP server onto the RX-8 core router and a PC on Fesx424 edge switch on the same Vlan (70) the BootP process doesn’t work.
If I configure both the BootP server onto the RX-8 core router and a PC on the router as well with the same Vlan (70) the BootP process doesn’t work.
The BootP server is listed as a helper address in the Vlan 70 interface (ve 70)
12-30-2010 01:54 PM
Configuring BootP/DHCP Forwarding Parameters
Beginning with release 02.7.00, the DHCP relay will allow for IP address grants that do not match the subnets configured on the interface that the DHCP request was received. 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 BigIron RX 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 BigIron RX does not forward the request.
You can configure the BigIron RX 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.
The IP subnet configured on the port which is directly connected to the device sending a BootP/DHCP request, does not have to match the subnet of the IP address given by the DHCP server.
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 on interface 2 on chassis module 1, enter the following commands:
BigIron RX(config)# interface e 1/2
BigIron RX(config-if-e1000-1/2)# ip helper-address 126.96.36.199
The commands in this example change the CLI to the configuration level for port 1/2, then add a helper address for server 188.8.131.52 to the port. If the port receives a client request for any of the applications that the BigIron RX is enabled to forward, the BigIron RX forwards the client’s request to the server.
ip helper-address <ip-addr>
The <ip-addr> command specifies the server’s IP address or the subnet directed broadcast address of the IP subnet the server is in.