Alcatel Omni Switch/Router, User Manual

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Page 26-1
26 UDP Forwarding
UDP
is a connectionless transport protocol that is used for applications that do not require the
establishment of a session and end-to-end error checking, such as email and file transfer. This
chapter describes the
UDP
relay function in the switch, which allows
UDP
broadcast packets
to be forwarded across groups and
VLAN
s that have IP routing enabled. The
UDP
relay allows
you to use nonroutable protocols in a routing environment. (For information about IP rout-
ing, see Chapter 25, “IP Routing.”)
♦
Note
♦
BOOTP
/
DHCP
relay has previously been available on
the switch. It is now part of an expanded feature that
includes relays for
NetBIOS
and generic services.
The relay may be configured for the following services:
• Bootstrap Protocol (
BOOTP
)/Dynamic Host Configuration Protocol (
DHCP
)
•
NetBIOS
Name Server (
NBNS
)
•
NetBIOS
Datagram Distribution Server (
NBDD
)
• Generic applications, such as Trivial File Transfer Protocol (
TFTP
)
The
UDP
services, their corresponding well-known port numbers, and configurable options
on the switch are listed here.
UDP Relay and RIF Stripping
Routing Information Field (
RIF)
stripping is required for transparent bridge ports in source
route environments and may also be useful in non-source route environments.
In a source route environment, where
RIF
stripping is enabled for transparent bridging to
Ethernet,
UDP
relay clients should not be more than one switch away from the
DHCP
server.
(In
RIF
stripping, 2 bytes are stripped from the
RIF
and each bridge adds 2 bytes to the
RIF
.
Packets with a
RIF
greater than 2 bytes are discarded.)
Service UDP Port No. Configurable Options
BOOTP/DHCP 67/68 Next-hop address (up to 8)
Forward delay
Maximum hops
NBNS 137 Next-hop address (up to 8)
Forwarding VLANs (up to 32)
NBDD 138 Next-hop address (up to 8)
Forwarding VLANs (up to 32)
Generic user-configured Next-hop address (up to 8)
Forwarding VLANs (up to 32)