3Com CoreBuilder 3500, Руководство по внедрению, Страница: 312 / 592

312 C
HAPTER
11: I
NTERNET
P
ROTOCOL
(IP)
You have to set the following UDP Helper parameters:
■
UDP port number
— A logical address, not a port (interface) on your
system. BOOTP (including DHCP) uses UDP port 67.
■
IP forwarding address
— The IP address to which the packets are
forwarded. You can have up to 63 combinations of port numbers and
IP forwarding addresses per router. You can also have multiple IP
address entries for the same ports.
■
Hop count — The number of interfaces the system uses to forward a
packet through the router.
■
Threshold — The maximum number of times that the system
forwards a packet to the network. By default, there is no BOOTP relay
threshold. (The default value is
0
. )
The commands to implement these parameters are described in the
chapter “IP Routing” in the
Command Reference Guide .
You need to have a thorough understanding of your network
configuration to use UDP Helper. Review the network topology before
you implement UDP Helper.
Configuring
Overlapped
Interfaces
Overlapped IP interfaces are multiple logical interfaces that are defined
for a single physical port. You can specify how UDP Helper forwards
packets from overlapped IP interfaces with one of these interface options:
■
First — The system uses the first overlapped IP interface of the port as
the source network for forwarded packets.
■
Even — The system hashes the MAC address of the client to
determine the source network for forwarded packets. This
arrangement evenly distributes the interface among those on the
network.
■
Sequential — The system assigns each overlapped IP interface, in
turn, as the source network for forwarded packets.
You can view the UDP Helper configuration when you configure the
forwarding address.