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FTOS Configuration Guide for the C-Series - Force10 Networks

FTOS Configuration Guide for the C-Series - Force10 Networks

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Packet 2 is sent from a host on VLAN 101. It has broadcast MAC address and a destination IP address that<br />

matches <strong>the</strong> configured broadcast address on VLAN 101. In this case, Packet 2 is flooded on VLAN 101<br />

with <strong>the</strong> destination address unchanged because <strong>the</strong> <strong>for</strong>warding process is Layer 2. If UDP helper is<br />

enabled, <strong>the</strong> packet is flooded on VLAN 100 as well.<br />

Figure 222 UDP Helper with Configured Broadcast Addresses<br />

Packet 1<br />

Destination Address:<br />

1.1.255.255<br />

Ingress interface<br />

IP Address: 2.1.1.1/24<br />

UDP helper enabled<br />

UDP Helper with No Configured Broadcast Addresses<br />

• If <strong>the</strong> incoming packet has a broadcast destination IP address, <strong>the</strong>n <strong>the</strong> unaltered packet is routed to all<br />

Layer 3 interfaces.<br />

• If <strong>the</strong> Incoming packet has a destination IP address that matches <strong>the</strong> subnet broadcast address of any<br />

interface, <strong>the</strong>n <strong>the</strong> unaltered packet is routed to <strong>the</strong> matching interfaces.<br />

Troubleshooting UDP Helper<br />

Display debugging in<strong>for</strong>mation using <strong>the</strong> command debug ip udp-helper, as shown in Figure 223.<br />

Figure 223 Debugging UDP Broadcast<br />

1/1<br />

Packet 2<br />

Switched Packet<br />

Destination Address:<br />

1.1.255.255<br />

330 IP Addressing<br />

1/3<br />

1/2<br />

VLAN 100<br />

IP address: 1.1.0.1/24<br />

Subnet broadcast address: 1.1.0.255<br />

Configured broadcast address: 1.1.255.255<br />

Hosts on VLAN 100: 1.1.0.2, 1.1.0.3, 1.1.0.4<br />

VLAN 101<br />

IP address: 1.11.1/24<br />

Subnet broadcast address: 1.1.1.255<br />

Configured broadcast address: 1.1.255.255<br />

Hosts on VLAN 100: 1.1.1.2, 1.1.1.3, 1.1.1.4<br />

fnC0048mp<br />

<strong>Force10</strong>(conf)# debug ip udp-helper<br />

01:20:22: Pkt rcvd on Gi 5/0 with IP DA (0xffffffff) will be sent on Gi 5/1 Gi 5/2 Vlan 3<br />

01:44:54: Pkt rcvd on Gi 7/0 is handed over <strong>for</strong> DHCP processing.

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