3Com 4007, Implementation Manual, Page: 394 / 684

394 C
HAPTER
16: IP R
OUTING
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 module uses the first overlapped IP interface of the port
as the source network for forwarded packets.
■
Even — The module 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 module 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.
Important
Considerations
Consider the following points when you use UDP Helper:
■
The maximum BOOTP hop count (how many steps the module uses to
forward a packet through the router) is 16; the default hop count limit
is
4
. Keep the hop count as low as possible for performance purposes.
■
3Com recommends that you keep the UDP port number at 67. The
port number 67, which is the industry standard, helps ensure that UDP
packets do not get dropped due to an unknown destination failure.
■
You can always add or remove a port number or IP forwarding address
defined for UDP Helper.