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Cisco CCNP / BCSI Test Tutorial: Broadcasts As well as theCisco CCNP / BCSI Exam Tutorial: Broadcasts And also the IP Helper-Tackle CommandAlthough routers accept and generate broadcasts, they do not ahead them. This may be rather a dilemma each time a broadcast must get to a tool for instance a DHCP or TFTP server that’s on just one aspect of the router with other subnets on one other side. If a PC tries to Identify a DNS server that has a broadcast, the published might be stopped by the router and will never get on the DNS server. By configuring the ip helper-address command to the router, UDP broadcasts including this tends to be translated into a unicast via the router, creating the interaction feasible. The command ought to be configured within the interface that will be acquiring the broadcasts.R1(config)#int e0R1(config-if)#ip helper-deal with ? A.B.C.D IP location handleR1(config-if)#ip helper-handle 100.1.one.twoNow, you might be questioning if this command handles all UDP solutions. Sorry, you’re not finding off that straightforward! The command does forward 8 popular UDP assistance broadcasts, while. TIME, port 37TACACS, port 49DNS, port fifty threeBOOTP/DHCP Server, port 67BOOTP/DHCP Consumer, port 68TFTP, port 69NetBIOS name support, port 137NetBIOS datagram support, port 138That’s intending to include most eventualities in which the ip helper-deal with command are going to be practical, but How about Individuals situations in which the broadcast you would like forwarded is not on this list? You can use the ip forward-protocol command to add any UDP port selection into the listing.Also, to eliminate protocols with the default list, use the no ip ahead-protocol command. In the subsequent case in point, we’ll increase the Community Time Protocol port to the forwarding record though eradicating the NetBIOS ports. Recall, You should utilize IOS Support to obtain a summary of normally filtered ports!R1(config)#ip ahead-protocol udp ? <0-65535> Port range biff Biff (mail notification, comsat, 512) bootpc Bootstrap Protocol (BOOTP) client (68) bootps Bootstrap Protocol (BOOTP) server (sixty seven) discard Discard (9) dnsix DNSIX security protocol auditing (195) domain Area fast Title Service (DNS, 53) echo Echo (seven) isakmp World-wide-web Protection Affiliation and Essential Administration Protocol (500) mobile-ip Cell IP registration (434) nameserver IEN116 name company (obsolete, forty two) netbios-dgm NetBios datagram services (138) netbios-ns NetBios title support (137) netbios-ss NetBios session company (139) ntp Community Time Protocol (123) pim-vehicle-rp PIM Automobile-RP (496) rip Routing Facts Protocol (router, in.routed, 520) snmp Uncomplicated Community Management Protocol (161) snmptrap SNMP Traps (162) sunrpc Sunshine Remote Process Simply call (111) syslog Method Logger (514) tacacs TAC Entry Regulate Method (forty nine) communicate Talk (517) tftp Trivial File Transfer Protocol (sixty nine) time Time (37) who Who support (rwho, 513) xdmcp X Show Manager Management Protocol (177