DHCP Address

[SathishkumarSaravanan0348]

Hello Experts,

I know the 4 stages of DHCP(DORA). I have seen in core switch that the dhcp server address are called under vlan. As per my knowledge the network scope will be added in dhcp server for the VLAN. I have couple of questions here.

doubts in the below questions

1. what happen if the same scope is created in another location, what type of conflict will happen?

2. How the SVI address(gateway) is configured. Whether it is configured as static(as the IP address should not change)?

3. How may days time interval does dhcp server offer an scope of address?

Regards,

Sathish 

[Deepak Kumar · Accepted solution]

Hi,

I am trying to explain your issues as:

1. what happen if the same scope is created in another location, what type of conflict will happen?

Ans: If the same scope is configured in another location and it is also offering IPs for the subnet (assuming that IP helper-address is added or two servers in the same network) then you may get duplicate IP address until you will not enabling "Detect Conflict" feature on the DHCP servers. We always recommend having a single DHCP server or device DHCP Scops on multiple servers with Detect Conflict and a half subnet on server Aand reset half subnet on Server B under the DHCP scope.

2. . How the SVI address(gateway) is configured. Whether it is configured as static(as the IP address should not change)?

Ans: The Gateway must be configured statically on the network.

3. How may days time interval does dhcp server offer an scope of address?

Ans: It depends on the "Lease Time" configuration on the server. It may differ based on the devices or software you used as a DHCP server. There is no recommendation but keep 24 hrs to 7 days so you can minimize the UDP flooding in the network. WIFI maybe 2 to 4 hrs.

[SathishkumarSaravanan0348]

Thanks for your response.

[paul driver · Accepted solution]

Hello

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@SathishkumarSaravanan0348 wrote:

Hello Experts,

I know the 4 stages of DHCP(DORA). I have seen in core switch that the dhcp server address are called under vlan. As per my knowledge the network scope will be added in dhcp server for the VLAN. I have couple of questions here.

doubts in the below questions

1. what happen if the same scope is created in another location, what type of conflict will happen? - Depending on what server answers the request first but you would be subjected to possible duplicate addressing and dns issues if dhcp is set to update dns also -  if you are going to have multiple servers and scope (very much recommended by the why for resiliency) you need to split the scope so half of it is active on one server and the other is active on the other server  then in time of any failure from either server you can simply activate the other half of the scope on the active server.

2. How the SVI address(gateway) is configured. Whether it is configured as static(as the IP address should not change)? If you mean on the dhcp scope then its applied when the scope is created, on the other if you mean an actual L3 switch SVI then that will hardcoded on the switch or router

3. How may days time interval does dhcp server offer an scope of address? This can vary! - On wifi networks you would want a very short lease due to wifi users roam and they come and go very quickly so a short lease (2hrs) would not only conserve your address dhcp allocation it will not exhaust it as quick.

As for more static devices -  workstation/laptops they usually have a 8 work day so a 12 hours lease would be possible, as for other device like printer/scanners/video conf stuff - well they are not going  anyway where so a much longer lease for these would be applicable.

Regards,

Sathish 

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[SathishkumarSaravanan0348]

Many Thanks for the response.