Service Manual
Figure 45. UDP Helper with Subnet Broadcast Addresses
UDP Helper with Congured Broadcast Addresses
Incoming packets with a destination IP address matching the congured broadcast address of any interface are forwarded to the
matching interfaces.
In the following illustration, Packet 1 has a destination IP address that matches the congured broadcast address of VLAN 100 and
101. If you enabled UDP helper and the UDP port number matches, the packet is ooded on both VLANs with an unchanged
destination address.
Packet 2 is sent from a host on VLAN 101. It has broadcast MAC address and a destination IP address that matches the congured
broadcast address on VLAN 101. In this case, Packet 2 is ooded on VLAN 101 with the destination address unchanged because the
forwarding process is Layer 2. If you enabled UDP helper, the packet is ooded on VLAN 100 as well.
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.
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IPv4 Routing