Concept Guide
Figure 46. UDP Helper with Congured Broadcast Addresses
UDP Helper with No Congured Broadcast Addresses
The following describes UDP helper with no broadcast addresses congured.
• 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 is
routed to the matching interfaces.
Troubleshooting UDP Helper
To display debugging information for troubleshooting, use the debug ip udp-helper command.
Example of the debug ip udp-helper Command
DellEMC(conf)# debug ip udp-helper
01:20:22: Pkt rcvd on Gi 5/1 with IP DA (0xffffffff) will be sent on Gi 5/2 Gi 5/3 Vlan 3
01:44:54: Pkt rcvd on Gi 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 Command
Packet 0.0.0.0:68 -> 255.255.255.255:67 TTL 128
2017-08-05 11:59:35 %RELAY-I-PACKET, BOOTP REQUEST (Unicast) received at interface
172.21.50.193 BOOTP Request, XID = 0x9265f901, secs = 0 hwaddr = 00:02:2D:8D:46:DC,
giaddr = 0.0.0.0, hops = 2
2017-08-05 11:59:35 %RELAY-I-BOOTREQUEST, Forwarded BOOTREQUEST for 00:02:2D:8D:46:DC
to 137.138.17.6
2017-08-05 11:59:36 %RELAY-I-PACKET, BOOTP REPLY (Unicast) received at interface
194.12.129.98 BOOTP Reply, XID = 0x9265f901, secs = 0 hwaddr = 00:02:2D:8D:46:DC,
giaddr = 172.21.50.193, hops = 2
2017-08-05 11:59:36 %RELAY-I-BOOTREPLY, Forwarded BOOTREPLY for 00:02:2D:8D:46:DC to
128.141.128.90 Packet 0.0.0.0:68 -> 255.255.255.255:67 TTL 128
412
IPv4 Routing