UDP Forwarding is a flexible and generalized routing utility for handling the directed forwarding of broadcast UDP packets. UDP Forwarding enables you to configure your switch so that inbound broadcast UDP packets on a VLAN are forwarded to a particular destination IP address or VLAN. 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 specified 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 TTL field (decrements), as appropriate.
If 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.
When using udp-profile to forward dhcp request, the behavior will be different from bootprelay. Where bootprelay will forward the dhcp packet with the client vlan IP as source IP, udp-profile will forward the dhcp packet with the source IP of the egress vlan towards the destination server.
UDP Forwarding only works across a Layer 3 boundary and currently, UDP Forwarding can be applied to IPv4 packets only, not to IPv6 packets.
NoteIn ExtremeXOS 22.6 and earlier, IPv4 UDP broadcast packets are forwarded to the destination IP address as configured in UDP policy without performing enable ipforwarding on the action VLAN. Starting with ExtremeXOS 30.1, IPv4 UDP broadcast packets are forwarded to destination IP address as configured in UDP policy only if enable ipforwarding is enabled on the action VLAN.