Allied Telesis AT-8550 - Manual (Page 142)

UDP-Forwarding
8-14
UDP-Forwarding
UDP-forwarding is a flexible and generalized routing utility for
handling the directed forwarding of broadcast UDP packets. UDP-
forwarding allows applications, such as multiple DHCP relay services
from differing sets of VLANs, to be directed to different DHCP servers.
The following rules apply to UDP broadcast packets handled by this
feature:
❑ If the UDP profile includes BootP or DHCP, it is handled
according to guidelines in RFC 1542.
❑ If the UDP profile includes other types of traffic, these packets
have the IP destination address modified as configured, and
changes are made to the IP and UDP checksums and
decrements to the TTL field, as appropriate.
If the UDP-forwarding is used for BootP or DHCP forwarding
purposes, do not configure or use the existing
bootprelay
function. However, if the previous bootprelay functions are
adequate, you may continue to use them.
Configuring
UDP-Forwarding
To configure UPD-forwarding, the first thing you must do is create a
UDP-forward destination profile. The profile describes the types of
UDP packets (by port number) that are used, and where they are to
be forwarded. You must give the profile a unique name, in the same
manner as a VLAN, protocol filter, or Spanning Tree Domain.
Next, configure a VLAN to make use of the UDP-forwarding profile.
As a result, all incoming traffic from the VLAN that matches the UDP
profile is handled as specified in the UDP-forwarding profile.
A maximum of ten UDP-forwarding profiles can be defined. Each
named profile may contain a maximum of eight “rules” defining the
UDP port, and destination IP address or VLAN. A VLAN can make use
of a single UDP-forwarding profile. UDP packets directed toward a
VLAN use an all-ones broadcast on that VLAN.