ECS4660-28F_Management Guide-R03

C HAPTER 17 | IP Services
Forwarding UDP Service Requests
– 733 –
Figure 436: Showing the UDP Destination Ports
SPECIFYING THE
TARGET SERVER OR
SUBNET
Use the IP Service > UDP Helper > Address page to specify the application
server or subnet (indicated by a directed broadcast address) to which
designated UDP broadcast packets are forwarded.
CLI REFERENCES
◆ "ip helper-address" on page 1661
COMMAND USAGE
◆ Up to 20 helper addresses can be specified.
◆ To forward UDP packets with the UDP helper, the clients must be
connected to the selected interface, and the interface configured with
an IP address.
◆ The UDP packets to be forwarded must be specified in the IP Service >
UDP Helper > Forwarding page, and the packets meet the following
criteria:
■
The MAC address of the received frame must be the all-ones
broadcast address (ffff.ffff.ffff).
■
The IP destination address must be one of the following:
■
all-ones broadcast (255.255.255.255)
■
subnet broadcast for the receiving interface
■
The IP time-to-live (TTL) value must be at least 2.
■
The IP protocol must be UDP (17).
■
The UDP destination port must be TFTP, Domain Name System
(DNS), Time, NetBIOS, BOOTP or DHCP packet, or a UDP port
specified on the IP Service > UDP Helper > Forwarding page.
◆ If a helper address is specified on this configuration page, but no UDP
ports have been specified on the IP Service > UDP Helper > Forwarding
page, broadcast traffic for several UDP protocol types will be forwarded
by default as described on page 731.