Extreme Networks ExtremeWare 7.2e, Installation And User Manual

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UDP-Forwarding
ExtremeWare 7.2e Installation and User Guide 229
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.
NOTE
UDP-forwarding only works across a layer 3 boundary.
Configuring UDP-Forwarding
To configure UDP-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.
UDP-Forwarding Example
In this example, the VLAN Marketing and the VLAN Operations are pointed toward a specific backbone
DHCP server (with IP address 10.1.1.1) and a backup server (with IP address 10.1.1.2). Additionally, the
VLAN LabUser is configured to use any responding DHCP server on a separate VLAN called LabSvrs.
The commands for this configuration are as follows:
create udp-profile backbonedhcp
create udp-profile labdhcp
configure backbonedhcp add 67 ipaddress 10.1.1.1
configure backbonedhcp add 67 ipaddress 10.1.1.2
configure labdhcp add 67 vlan labsvrs
configure marketing udp-profile backbonedhcp
configure operations udp-profile backbonedhcp
configure labuser udp-profile labdhcp