Cisco CCNP / BCSI Exam Tutorial: Broadcasts And The IP Helper-Tackle Command
While routers settle for and generate broadcasts, they do not ahead them. This may be fairly a dilemma every time a broadcast should get to a device for instance a DHCP or TFTP server that’s on one particular facet of the router with other subnets on another facet.
If a Laptop attempts to Track down a DNS server with a broadcast, the published might be stopped from the router and will never get to the DNS server. By configuring the ip helper-deal with command to the router, UDP broadcasts for example this could be translated right into a unicast with the router, creating the interaction achievable. The command should be configured over the interface that can be obtaining the broadcasts.
R1(config)#int e0
R1(config-if)#ip helper-tackle ?
A.B.C.D IP spot address
R1(config-if)#ip helper-address 100.one.1.two
Now, you could be wondering if this command addresses all UDP services. Sorry, you’re not acquiring off that quick! The command does forward 8 typical UDP services broadcasts, while.
TIME, port 37
TACACS, port 49
DNS, port fifty three
BOOTP/DHCP Server, port sixty seven
BOOTP/DHCP Client, port 68
TFTP, port sixty nine
NetBIOS identify company, port 137
NetBIOS datagram provider, port 138
That’s about to go over most situations in which the 안전놀이터 ip helper-deal with command will be valuable, but what about Those people scenarios wherever the broadcast you require forwarded just isn't on this record? You should utilize the ip ahead-protocol command to include any UDP port quantity on the list.
Also, to remove protocols within the default list, utilize the no ip ahead-protocol command. In the next instance, we’ll add the Network Time Protocol port towards the forwarding list when eradicating the NetBIOS ports. Remember, You need to use IOS Assist to receive a summary of typically filtered ports!
R1(config)#ip ahead-protocol udp ?
<0-65535> Port number
biff Biff (mail notification, comsat, 512)
bootpc Bootstrap Protocol (BOOTP) shopper (68)
bootps Bootstrap Protocol (BOOTP) server (67)
discard Discard (nine)
dnsix DNSIX protection protocol auditing (195)
domain Area Name Services (DNS, fifty three)
echo Echo (7)
isakmp World wide web Security Association and Essential Management Protocol (500)
cellular-ip Cell IP registration (434)
nameserver IEN116 identify assistance (obsolete, forty two)
netbios-dgm NetBios datagram services (138)
netbios-ns NetBios name support (137)
netbios-ss NetBios session assistance (139)
ntp Network Time Protocol (123)
pim-car-rp PIM Vehicle-RP (496)
rip Routing Information and facts Protocol (router, in.routed, 520)
snmp Easy Network Administration Protocol (161)
snmptrap SNMP Traps (162)
sunrpc Sunlight Remote Technique Contact http://www.bbc.co.uk/search?q=토토사이트 (111)
syslog System Logger (514)
tacacs TAC Entry Regulate Procedure (49)
chat Converse (517)
tftp Trivial File Transfer Protocol (69)
time Time (37)
who Who company (rwho, 513)
xdmcp X Exhibit Supervisor Control Protocol (177)