splitting dhcp scope

we currently have a cluster which is servicing dhcp and wins.

Is it possible to have 2 servers that I can split up the dhcp scope and
still have redundancy if one server fails without using clustering?

"Joey" <(E-Mail Removed)> wrote in message news:%(E-Mail Removed)...
> we currently have a cluster which is servicing dhcp and wins.
>
> Is it possible to have 2 servers that I can split up the dhcp scope and
> still have redundancy if one server fails without using clustering?
>
>


Yes, usually the 80/20 rule would apply. This would be a backup strategy if one of them were to go down. You can also opt for a 50/50 strategy, too for load balancing, but they cannot be combined between two different DHCP servers.

80/20 RuleFor balancing DHCP server usage, use the 80/20 rule to divide scope addresses between DHCP servers. Figure 4.11 is an example of the 80/20 rule. ...
http://technet.microsoft.com/en-us/l.../cc958936.aspx

Configuring scopes: Dynamic Host Configuration Protocol (DHCP)Jan 21, 2005 ... For balancing DHCP server usage, a good practice is to use the "80/20" rule to divide the scope addresses between the two DHCP servers. ....
http://technet.microsoft.com/en-us/l...76(WS.10).aspx

--
Ace

This posting is provided "AS-IS" with no warranties or guarantees and
confers no rights.

Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSA Messaging, MCT
Microsoft Certified Trainer
(E-Mail Removed)

For urgent issues, you may want to contact Microsoft PSS directly. Please
check http://support.microsoft.com for regional support phone numbers.

"Efficiency is doing things right; effectiveness is doing the right things." - Peter F. Drucker
http://twitter.com/acefekay

If I go with 80/20 rule. what happens if one for the dhcp server fails or go
offline? what do I do with clients that cannot get IP address on the server
that does not have a scope configured
"Ace Fekay [Microsoft Certified Trainer]" <(E-Mail Removed)>
wrote in message news:%(E-Mail Removed)...
"Joey" <(E-Mail Removed)> wrote in message
news:%(E-Mail Removed)...
> we currently have a cluster which is servicing dhcp and wins.
>
> Is it possible to have 2 servers that I can split up the dhcp scope and
> still have redundancy if one server fails without using clustering?
>
>


Yes, usually the 80/20 rule would apply. This would be a backup strategy if
one of them were to go down. You can also opt for a 50/50 strategy, too for
load balancing, but they cannot be combined between two different DHCP
servers.

80/20 RuleFor balancing DHCP server usage, use the 80/20 rule to divide
scope addresses between DHCP servers. Figure 4.11 is an example of the 80/20
rule. ...
http://technet.microsoft.com/en-us/l.../cc958936.aspx

Configuring scopes: Dynamic Host Configuration Protocol (DHCP)Jan 21, 2005
.... For balancing DHCP server usage, a good practice is to use the "80/20"
rule to divide the scope addresses between the two DHCP servers. ...
http://technet.microsoft.com/en-us/l...76(WS.10).aspx

--
Ace

This posting is provided "AS-IS" with no warranties or guarantees and
confers no rights.

Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSA Messaging, MCT
Microsoft Certified Trainer
(E-Mail Removed)

For urgent issues, you may want to contact Microsoft PSS directly. Please
check http://support.microsoft.com for regional support phone numbers.

"Efficiency is doing things right; effectiveness is doing the right
things." - Peter F. Drucker
http://twitter.com/acefekay

"Joey" <(E-Mail Removed)> wrote in message news:%(E-Mail Removed)...
> If I go with 80/20 rule. what happens if one for the dhcp server fails or go
> offline? what do I do with clients that cannot get IP address on the server
> that does not have a scope configured


The 80/20 rule means both servers have a scope configured, so I'm not sure what you mean? Check out the articles. The main server will have 80% of the scope, the other having 20%. If the main one goes down, the other will keep giving out addresses until you get the first one up.

Or did you mean something else?

Ace

Why in the world did they ever dream up the 80/20 idea when the 50/50 is so
much more logical?


--
Phillip Windell

The views expressed, are my own and not those of my employer, or Microsoft,
or anyone else associated with me, including my cats.
-----------------------------------------------------


"Ace Fekay [Microsoft Certified Trainer]" <(E-Mail Removed)>
wrote in message news:(E-Mail Removed)...
"Joey" <(E-Mail Removed)> wrote in message
news:%(E-Mail Removed)...
> If I go with 80/20 rule. what happens if one for the dhcp server fails or
> go
> offline? what do I do with clients that cannot get IP address on the
> server
> that does not have a scope configured


The 80/20 rule means both servers have a scope configured, so I'm not sure
what you mean? Check out the articles. The main server will have 80% of the
scope, the other having 20%. If the main one goes down, the other will keep
giving out addresses until you get the first one up.

Or did you mean something else?

Ace

Just add both ip's of the DHCP servers, to your helper address on the router
per subnet
"Phillip Windell" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Why in the world did they ever dream up the 80/20 idea when the 50/50 is
> so much more logical?
>
>
> --
> Phillip Windell
>
> The views expressed, are my own and not those of my employer, or
> Microsoft,
> or anyone else associated with me, including my cats.
> -----------------------------------------------------
>
>
> "Ace Fekay [Microsoft Certified Trainer]" <(E-Mail Removed)>
> wrote in message news:(E-Mail Removed)...
> "Joey" <(E-Mail Removed)> wrote in message
> news:%(E-Mail Removed)...
>> If I go with 80/20 rule. what happens if one for the dhcp server fails or
>> go
>> offline? what do I do with clients that cannot get IP address on the
>> server
>> that does not have a scope configured
>
>
> The 80/20 rule means both servers have a scope configured, so I'm not sure
> what you mean? Check out the articles. The main server will have 80% of
> the scope, the other having 20%. If the main one goes down, the other will
> keep giving out addresses until you get the first one up.
>
> Or did you mean something else?
>
> Ace
>

my thought you cannot have 2 dhcp servers on the same network. If I do have
2 dhcp servers, any client on the network will get an ip from the first dhcp
that responds? I still dont understand what 80/20 mean. from the diagram. I
see the same scope configured on both servers but on different subnets.

for our network, we only have one dhcp cluster servicing multiple vlans. I
believe the router is doing some dhcp helper thing to help clients from
different subnets find the dhcp cluster.


"Ace Fekay [Microsoft Certified Trainer]" <(E-Mail Removed)>
wrote in message news:(E-Mail Removed)...
"Joey" <(E-Mail Removed)> wrote in message
news:%(E-Mail Removed)...
> If I go with 80/20 rule. what happens if one for the dhcp server fails or
> go
> offline? what do I do with clients that cannot get IP address on the
> server
> that does not have a scope configured


The 80/20 rule means both servers have a scope configured, so I'm not sure
what you mean? Check out the articles. The main server will have 80% of the
scope, the other having 20%. If the main one goes down, the other will keep
giving out addresses until you get the first one up.

Or did you mean something else?

Ace

"Joey" <(E-Mail Removed)> wrote in message
news:%(E-Mail Removed)...
> my thought you cannot have 2 dhcp servers on the same network. If I do
> have

Yes you can

> 2 dhcp servers, any client on the network will get an ip from the first
> dhcp that responds?

Yes that is correct.

> I still dont understand what 80/20 mean. from the diagram. I see the same
> scope configured on both servers but on different subnets.

It is the same identical Scope except that Exclusions are use on each that
limit what IP#s it can actually give out to Clients. I never do 80/20,..it
doesn't make good sense to me,..I always do 50/50. One DHCP gives out the
first half of the available addresses,...the second DHSP gives out the
second half of the addresses (hence 50/50).

--
Phillip Windell

The views expressed, are my own and not those of my employer, or Microsoft,
or anyone else associated with me, including my cats.
-----------------------------------------------------

"Joey" <(E-Mail Removed)> wrote in message news:%(E-Mail Removed)...
> my thought you cannot have 2 dhcp servers on the same network. If I do have
> 2 dhcp servers, any client on the network will get an ip from the first dhcp
> that responds? I still dont understand what 80/20 mean. from the diagram. I
> see the same scope configured on both servers but on different subnets.
>
> for our network, we only have one dhcp cluster servicing multiple vlans. I
> believe the router is doing some dhcp helper thing to help clients from
> different subnets find the dhcp cluster.


The 80/20, or preferrably as Phillip mentioned, 50/50 idea has been around for quite some time. You can have two DHCP servers but as long as the IP ranges do not cross, you are good to go.

Ace

That's exactly how we do it too. We just make sure that each server has
a large enough scope to handle the entire network if it has to.

--
-Ben-
Ben M. Schorr, MVP
Roland Schorr & Tower
http://www.rolandschorr.com
http://www.officeforlawyers.com
Author - The Lawyer's Guide to Microsoft Outlook 2007:
http://tinyurl.com/5m3f5q



"Phillip Windell" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed):

> It is the same identical Scope except that Exclusions are use on each that
> limit what IP#s it can actually give out to Clients. I never do 80/20,..it
> doesn't make good sense to me,..I always do 50/50. One DHCP gives out the
> first half of the available addresses,...the second DHSP gives out the
> second half of the addresses (hence 50/50).
>
> --
> Phillip Windell
>
> The views expressed, are my own and not those of my employer, or Microsoft,
> or anyone else associated with me, including my cats.
> -----------------------------------------------------