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Figure 56. ICMP Redirect
Host H is connected to the same Ethernet segment as SW1 and SW2. SW1 and SW2 are multi-layer switches which can route
packets. The default gateway of Host H is configured as SW1. Although the best route to the remote branch office host may
be through SW2, Host H sends a packet destined for Host R to its default gateway SW1. After SW1 finds that the route to
Host R is through SW2, and that SW1 must forward the packet out the same Ethernet interface on which packet was received,
it forwards the packet to SW2 and sends an ICMP redirect message to Host H. Host H learns of the new route using the ICMP
redirect message and sends all future packets to the remote branch office host to SW2.
To enable ICMP or ICMP6 redirect messages, use the icmp6-redirect enable command.
NOTE: The icmp6-redirect enable command is applicable for both ICMP and ICMP6 redirects.
By default, Dell EMC Networking OS supports redirects on VLAN interfaces. For physical ports and port channel interfaces,
carve the fedgovacl CAM region.
UDP Helper
User datagram protocol (UDP) helper allows you to direct the forwarding IP/UDP broadcast traffic by creating special
broadcast addresses and rewriting the destination IP address of packets to match those addresses.
Configure UDP Helper
To configure Dell EMC Networking OS to direct UDP broadcast, enable UDP helper and specify the UDP ports for which traffic
is forwarded. See Enabling UDP Helper
Important Points to Remember
The existing ip directed broadcast command is rendered meaningless if you enable UDP helper on the same
interface.
The broadcast traffic rate should not exceed 200 packets per second when you enable UDP helper.
You may specify a maximum of 16 UDP ports.
UDP helper is compatible with IP helper (ip helper-address):
IPv4 Routing
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