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DHCP helper-address and pool

aweise
Level 1
Level 1

I would think the answer to this is pretty simple, but I can't confirm.

 

At one of our remote locations, we have a layer 3 switch (Cisco 3850) that has a DHCP pool configured for our IP phones. However, on the VLAN interface for the phone VLAN, we also have a helper-address configured. Configurations are below:

 

ip dhcp pool VOIP
 network 10.1.26.0 255.255.255.0
 default-router 10.1.26.1

 

interface Vlan500
 ip address 10.1.26.1 255.255.255.0
 ip helper-address 192.168.10.10
 ip helper-address 192.168.20.10

 

If the helper address is configured on the SVI, does the local pool on the switch simply override the helper-address? The pool on the switch is responding to the queries and successfully handing out the IP address leases.

 

 

 

 

1 Accepted Solution

Accepted Solutions
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BradEast1
Level 3
Level 3

Not certain that one negates the other. My logic would be that it's faster to get a response from the local DHCP pool rather than convert the request to unicast, forward to your remote DHCP server and receive a response. Thus, the local pool would win.

Yachay
Level 1
Level 1

Yachay, thank you for that link. My guess is what BradEast1 said in that the switch would respond more quickly than the remote DHCP server.

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