Udp Helper With Configured Broadcast Addresses; Udp Helper With No Configured Broadcast Addresses - Dell Force10 S4810P Configuration Manual

Start Frame
Preamble
Delimiter

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 UDP helper is enabled 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 UDP helper is
enabled, the packet is flooded on VLAN 100 as well.
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, then 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, then the unaltered packet is routed to the matching interfaces.
534
| IPv4 Routing
Destination MAC Ethernet Type
Source MAC
(01:80:C2:00:00:0E) (0x88CC)
TLV 1 TLV 2 TLV 3
Chassis ID Port ID Port Description
1/1
Ingress interface
IP Address: 2.1.1.1/24
UDP helper enabled
Packet 2
Switched Packet
Destination Address:
1.1.255.255
LLDPDU
TLV 6
TLV 4 TLV 5
System Name System Description System Capabilities
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
Padding FCS
TLV 7 TLV 127
Management Addr Organizationally Specific
1.1.255.255
fnC0048mp
TLV 0
End of LLDPDU