Cisco ip helper-address (and related services)

 

The Helper Address Router does not send broadcasts. The help Address helps the client establish contact with the server by directly forwarding these broadcast packets to the target server. The help address command changes the Broadcast Destination Address to the single-point transfer room delivery address (or a targeted broadcast-this broadcast in a subnet ), this allows the broadcast message to be routed to a specific destination rather than all places. Use the ip helper-address interface configuration command to configure an interface that may receive the broadcast. In this command, ADDRESS refers to the destination used to forward User Datagram Protocol (UDP) broadcasts.

Helper Address)

Vro does not distribute broadcasts. The help address helps the client establish contact with the server by directly forwarding these broadcast packets to the target server.

The help address command changes the Broadcast Destination Address to the single-point transfer room delivery address (or a targeted broadcast-this broadcast in a subnet ), enables the broadcast message to be routed to a specific destination instead of all places.

Use the "ip helper-address" interface to configure the command to configure an interface that may receive broadcasts. In this command, "ADDRESS" refers to the destination ADDRESS used to forward User Datagram Protocol (UDP) broadcasts. The specified address can be a single point transfer address or a targeted broadcast address of the remote server.

If the "ip helper-address" command is defined, the forwarding function for eight default UDP ports is automatically enabled, which are: TFTP (69), DNS (53), time (37), NETBIOS service (137), n etbios datagram Service (138), BOOTP server (67), BOOTP client (68) and the access control system TACACS (49 ).

If the "ip helper-address" command is defined and the "ip forward-protocol udp" command is defined for the eight u d p ports, then the broadcast data packets destined for these eight UDP ports are automatically forwarded.

"Ip forward-protocol" Description:

"Ip forward-protocol" command description

UdpUDP-Transport Layer Protocol

Port (optional) when the "udp" keyword is specified, you can define the UDP destination port number or port name

Nd Network Disk; an old protocol used by the diskless Sun Workstation

Sdns Network Security Protocol

Instance:

Interface Ethernet 0

Ip address 172.16.1.100 255.255.255.0

Ip helper-address 172.16.2.2

Ip forward-protocol udp 3000

No ip forward-protocol udp tftp