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TOPIC: ip helper

ip helper 8 years 4 months ago #26029

I'm looking for a clear detailing of how the "ip helper" command works. Anyone out there know this command's syntax and functionality inside and out? :?:
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Re: ip helper 8 years 4 months ago #26030

  • S0lo
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As far as I know, you use it to let the router work as a DHCP agent. forwarding all DHCP broadcasts to a DHCP server at another sub-net.

The following is what appears in ciscopedia:


Syntax:
ip helper-address address

no ip helper-address address

Syntax Description:
address Destination broadcast or host address to be used when forwarding UDP broadcasts. There can be more than one helper address per interface.

Command Description:
To have the Cisco IOS software forward User Datagram Protocol (UDP) broadcasts, including BOOTP, received on an interface, use the ip helper-address interface configuration command. To disable the forwarding of broadcast packets to specific addresses, use the no form of this command.

Example:
Router(config-if)#ip helper-address 121.24.43.2
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Ammar Muqaddas
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Off to a good start 8 years 4 months ago #26031

I try in any thread I start to not just get an answer for myself, but to make my thread a go-to source of information for people who are interested in learning more or trying to tackle a problem that involves what I'm discussing in the future.

That said, it appears we're off to a good start. Anyone else care to throw their hat in the ring with their own explanation? How about an explanation in more clear terms than Cisco offers.
CPU: AMD Athlon 64 3700+ San Diego 2.2GHz Socket 939 Processor
MOBO: DFI LANPARTY nF4 SLI-DR 939 NVIDIA nForce4 SLI ATX AMD Motherboard
RAM: Crucial Ballistix 1GB (2 x 512MB) 184-Pin DDR SDRAM DDR 400 (PC 3200) Dual Channel Kit
GFX: eVGA GeForce 880
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Re: ip helper 8 years 4 months ago #26120

  • skepticals
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In my terms, the ip-helper command will take a broadcast packet and sent it out unicast to a specific computer/device like a dhcp server.

I normally use the ip-helper command to forward the DHCP broadcasts to a server-based DHCP server.

The ip-helper command also sends other types of packets.
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