Figure 54. UDP Helper with Configured Broadcast AddressesUDP Helper with No Configured Broadcast AddressesThe following describes UDP helper with no broadcast addresses configured.• If the incoming packet has a broadcast destination IP address, the unaltered packet is routed to all Layer 3 interfaces.• If the Incoming packet has a destination IP address that matches the subnet broadcast address of any interface, the unaltered packet isrouted to the matching interfaces.Troubleshooting UDP HelperTo display debugging information for troubleshooting, use the debug ip udp-helper command.Example of the debug ip udp-helper CommandDell(conf)# debug ip udp-helper01:20:22: Pkt rcvd on Te 5/1 with IP DA (0xffffffff) will be sent on Te 5/2 Te 5/3 Vlan 301:44:54: Pkt rcvd on Te 7/1 is handed over for DHCP processing.When using the IP helper and UDP helper on the same interface, use the debug ip dhcp command.Example Output from the debug ip dhcp CommandPacket 0.0.0.0:68 -> 255.255.255.255:67 TTL 1282005-11-05 11:59:35 %RELAY-I-PACKET, BOOTP REQUEST (Unicast) received at interface172.21.50.193 BOOTP Request, XID = 0x9265f901, secs = 0 hwaddr = 00:02:2D:8D:46:DC,giaddr = 0.0.0.0, hops = 22005-11-05 11:59:35 %RELAY-I-BOOTREQUEST, Forwarded BOOTREQUEST for 00:02:2D:8D:46:DCto 137.138.17.62005-11-05 11:59:36 %RELAY-I-PACKET, BOOTP REPLY (Unicast) received at interface194.12.129.98 BOOTP Reply, XID = 0x9265f901, secs = 0 hwaddr = 00:02:2D:8D:46:DC,giaddr = 172.21.50.193, hops = 22005-07-05 11:59:36 %RELAY-I-BOOTREPLY, Forwarded BOOTREPLY for 00:02:2D:8D:46:DC to128.141.128.90 Packet 0.0.0.0:68 -> 255.255.255.255:67 TTL 128IPv4 Routing 449
