Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

redundant ip helper-address


In 3560 with IPbase IOS image how can we acheine DHCP redundancy?

If we give two commands

ip helper-address IP1

ip helper-address IP2

in the VLAN interface will it work?

If dhcp IP1 is down can client get IP from dhcp IP2 ?

Please share the experience.

Any link on is highly appreciable.

thanks in advance.


  • WAN Routing and Switching
Hall of Fame Super Silver

Re: redundant ip helper-address

Hello Subodh,

yes multiple ip helper address commands are supported but the router uses all of them at once: each broadcast is translated multiple times to each ip helper address unicast destination.

Faster anwer or some other form of control allows for managing the DHCP server redundancy.

if servers can talk to each other you can define the same scope on both.

We do so with Cisco network registrar.

other colleagues have reported that when the two servers are indipendent they configure two different scopes on the two servers taken from the same ip subnet.

so this works for servers in cluster and also for indipendent servers with the trick suggested above.

Hope to help


New Member

Re: redundant ip helper-address

Ho Subodh,

redundancy is implemented in the DHCP Protocol. Check

You can also use a boadcast adress as helper adress when you enable ip directed-broadcast in the target VLAN of the helper address. So if your dhcp servers in vlan 100 with ip subnet 10.1.1.x/24, add ip helper-address in the client vlans, and add ip directed-broadcast in the VLAN100 of the DHCP Servers.