Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.100.0 - Page 414
UDP Helper with Con d Broadcast Addresses, UDP Helper with No Con d Broadcast Addresses
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Figure 51. UDP Helper with Subnet Broadcast Addresses UDP Helper with Configured Broadcast Addresses Incoming packets with a destination IP address matching the configured 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 configured broadcast address of VLAN 100 and 101. If you enabled UDP helper and the UDP port number matches, the packet is flooded 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 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 52. UDP Helper with Configured Broadcast Addresses UDP Helper with No Configured Broadcast Addresses The 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 is routed to the matching interfaces. 414 IPv4 Routing
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