Udp Helper With No Configured Broadcast Addresses; Troubleshooting Udp Helper - Dell Force10 MXL Blade Configuration Manual

Packet 2 is sent from a host on VLAN 101. It has broadcast MAC address and a destination IP address that
matches the configured broadcast address on VLAN 101. In this case, Packet 2 is flooded on VLAN 101
with the destination address unchanged because the forwarding process is Layer 2. If you enabled UDP
helper, the packet is flooded on VLAN 100 as well.
Figure 14-14. UDP Helper with Configured Broadcast Addresses
Packet 1
Destination Address:
1.1.255.255

UDP Helper with No Configured Broadcast Addresses

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, use the
Figure 14-15. Debugging UDP Broadcast
FTOS(conf)# debug ip udp-helper
01:20:22: Pkt rcvd on TenGig 5/0 with IP DA (0xffffffff) will be sent on TenGig 5/1 TenGig 5/
2 Vlan 3
01:44:54: Pkt rcvd on TenGig 7/0 is handed over for DHCP processing.
When using the IP helper and UDP helper on the same interface, use the
(Figure 14-16).
1/1
Ingress interface
IP Address: 2.1.1.1/24
UDP helper enabled
Packet 2
Switched Packet
Destination Address:
1.1.255.255
VLAN 100
IP address: 1.1.0.1/24
Subnet broadcast address: 1.1.0.255
Configured broadcast address:
Hosts on VLAN 100: 1.1.0.2, 1.1.0.3, 1.1.0.4
1/2
1/3
VLAN 101
IP address: 1.11.1/24
Subnet broadcast address: 1.1.1.255
Configured broadcast address: 1.1.255.255
Hosts on VLAN 100: 1.1.1.2, 1.1.1.3, 1.1.1.4
command
debug ip udp-helper
1.1.255.255
fnC0048mp
(Figure 14-15).
command
debug ip dhcp
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