Cisco DHCP Relay vs IP Helper: Difference and Comparison

Cisco DHCP Relay and IP Helper are the terms related to the Cisco routers. Their configuration differs as to which one we can enable and disable.

They are the two most vital elements in the system. DHCP is the abbreviation for Dynamic Host Configuration Protocol.

IP is the abbreviation for Internet protocol.

They both are very important and interesting in their ways. Let us get into some detailed information to know more about them.

Key Takeaways

  1. DHCP Relay forwards DHCP requests from clients to servers, while IP Helper forwards various broadcast packets.
  2. DHCP Relay specifically assists with IP address assignment, while IP Helper supports several protocols, including DHCP, BOOTP, and TFTP.
  3. Configuring DHCP Relay requires identifying the DHCP server, while IP Helper configuration specifies the helper address.

Cisco DHCP Relay vs IP Helper

The difference between Cisco DHCP Relay and IP Helper is that they are kind of the same thing but different vendors. DHCP Relay is the concept where the server and the medium are not on the same LAN, yet the host or medium might get a server from another LAN. In IP helper, the address of a server is located in a different LAN from which requests are answered.

Cisco DHCP Relay vs IP Helper
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DHCP Relay is a medium or host used to forward requests and replies among the server and clients. It is done when the server is on a different network.

Their function is first to receive a DHCP message, then introduce another new one, and finally send it to the interface.

The IP helper is present as a pre-installed program in windows 10. It works on its own by default, and we need not configure it unless necessary.

However, disabling it does not cause any harm to the system unless there is a connectivity issue.

Comparison Table

ParametersDHCP relayIP Helper
FunctionWith the help of commands, DHCP Relay can also configure the router.   IP helper does not forward a broadcast request to the server by default.  
SettingsIt is not our choice to enable DHCP Relay.  We can disable and again reenable the IP helper according to our will.  
ServerDSCP relay forward between server and client when a server is present.  IP helper does not forward a broadcast request to the server by default.  
AdvantageDHCP Relay, with the help of commands, can also configure the router.    IP helper has no such advantage or facility.  
AbilityDSCP relay refers to the ability of the host to forward DHCP packets.  The IP address refers to the cisco syntax.  

What is Cisco DHCP Relay?

A Cisco DHCP Relay refers to any medium forwarding DHCP packets between a server and a client. This is when the server and the client are not on the same physical subnet.

It is software included under Cisco routers. They are enabled by default.

However, we can check the configuration file to see if they are disabled. To reenable it, the service DHCP command is used.

After receiving a DHCP message, the relay agent generates a new DHCP message and sends it to another interface.

A great advantage of Cisco DHCP is that it supports the usage of an unnumbered interface. It automatically hosts a static host route to connect the clients through unnumbered interfaces.

It is possible specifically when the client obtains the address and also the unnumbered interface as an outbound interface.

A Cisco DHCP can also receive a message from another DHCP that contains any DHCP information. In such cases, the relay information from the previous relay is replaced.

This process takes place by default. However, it might not be suitable for our network every time.

We can use the ‘IP DHCP relay information policy’ to configure it.

What is IP Helper?

IP helper helps in the network administration of computers by the process of retrieving network configuration information. It helps to modify the configuration of local computers.

In other words, we can say it is a router function that enables broadcast traffic to mass between several networks in a systematic way.

It consists of IP Helper addresses. It refers to the IP addresses that are configured on a routed interface.

By routed interface, it means that a specific device that acts as a medium.

It is suggested not to change the default configuration unless required. It is safe to leave it running in the background without any obstacles.

However, if there is a reason to disable it, it is safe to do so. Stopping the IP helper does not affect the system in an adverse manner.

There is an IP forward-protocol system. In this system, the router is set to forward ND packets for a workstation that does not possess disks.

The HTTP server has an IP HTTP router. It denotes that nothing else is connected to the router.

Main Differences Between Cisco DHCP Relay and IP Helper

  1.  Cisco DHCP Relay is used to forward the requests from broadcast to the central server. On the other hand, the IP helper is the command required to process the DHCP relay in routers.
  2. With the help of commands, DHCP Relay can also configure the router. In contrast, IP helper has no such advantage or facility.
  3. It is not our choice to enable DHCP Relay. However, we can disable and again reenable the IP helper according to our will.
  4. DSCP relay forward between server and client when a server is present. IP helper does not forward a broadcast request to the server by default.
  5. DSCP relay refers to the ability of the host to forward DHCP packets. The IP address refers to the cisco syntax.
References
  1. https://ieeexplore.ieee.org/abstract/document/9297852/
  2. https://ieeexplore.ieee.org/abstract/document/9297852/

Last Updated : 13 July, 2023

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