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Hello I wanted to see if someone could help with a network problem I am having. Right now we have a super-scope and scopes of 192.168.50.1 and 192.168.51.1, as of now both are activated but only 192.168.50.1 is handing our leases, 192.168.51 wont. here is a summary of our network

Gateway: watchguard firebox x750e for our router/gateway at 192.168.50.1 I set up as a secondary IP address 192.168.51.1

Server: Server 2008 r2 standard, running our DNS @ 192.168.50.242 and 8.8.8.8 as a secondary, AD, and DHCP. On that NIC card i have 192.168.50.242 as the IP address and 192.168.51.242 as a secondary. 192.168.50.1 as the default gateway and 192.168.51.1 as a secondary.

Im am not very knowledgeable at this but as far as i have researched after adding a super scope and activating scopes, they should automatically start handing out addresses and I cant figure out why only one does. any help at all would be appreciated.

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Have you created any VLANs? What was the reasoning behind using superscopes and not scopes when the DHCP role was configured? –  Colyn1337 May 29 at 18:26
    
Why are you using a superscope? –  joeqwerty May 29 at 18:54
    
No VLANs, we have the scopes inside of the superscope and I did not originally set this up. the previous IT guy did but he told me it would work fine when activating the second scope and that didn't happen. Not sure if he blows smoke sometimes. –  Vdub May 29 at 19:55

3 Answers 3

up vote 1 down vote accepted

There is probably no reason to keep it like this, it's unnecessarily complicated. 192.168.50.0/24 and 192.168.51.0/24 can be combined into one subnet, 192.168.50.0/23, so you could reconfigure that on the DHCP server and get rid of the Superscope. Then configure it as 192.168.50.0/23 on the router/vlan as well. The only issue is going to be subnet mask and gateway on statically configured devices, so you might have numerous touch points. DHCP clients will pick up the new subnet mask next time they renew.

It's probably the case that you ran out of IPs on 192.168.50.0/24 at some point and another was added as a "secondary" as a quick and dirty way to get more address space on that wire/vlan. Superscope is a way to join those two /24's on the DHCP side telling the DHCP server that both of these scopes are on the same wire and thus recognize that any clients or relay agents coming from either subnet should be treated as being on the same wire/vlan. This is more commonly used when the subnets are non-continguous, e.g., if it was 192.168.50.0/24 originally then you added 192.168.66.0/24 as a secondary network to get more space.

The behavior you see is thus normal. You won't see the DHCP server start handing out addresses from the newly-enabled scope (under the Superscope) until all addresses in the first scope (192.168.50.1) are all used up. And existing DHCP clients will continue to directly renew the IP they already have.

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Sounds great thanks for the help. One more question, on my DHCP server's NIC card should I have 50 and 51 IP addresses, gateway and DNS or will it just keep it all on x.x.50.x? –  Vdub Jun 2 at 17:52
    
If you convert over to 192.168.50.0/23, then your only gateway is 192.168.50.1 and you only need one address on the NIC and it can be the 50.x or 51.x but you don't need both anymore. –  milli Jun 2 at 20:45

Are you sure you are really having a problem?

Superscopes are useful when you join two physical subnets, each with its own scope and DHCP server. They solve the following problem: client disconnects from scope A, then reconnects and asks for renewal of lease, but server B is quicker and, ignoring the existence of a superscope, declines the request of lease renewal; the client will then have to re-issue a DHCP discovery signal, and may be offered a lease by server B within scope B. Thus the client is now cut-off from its original network, and inserted into a subnet for which it may not be configured. This may happen every time every client disconnects.

By configuring a superscope, you are basically allowing server B, now assumed to be aware of its participation in a wider scope than its own subnet, to renew the lease of the client in subnet A, basically keeping all configurations intact.

In your network, you have a single DHCP server, and, if I understand right, a single physical network. Thus there is no difference between a superscope and a single scope with netmask 255.255.254.0 instead of the usual 255.255.255.0. Since there is only one DHCP, it will start dishing out addresses in the 192.168.51.0/24 scope only after it has exhausted addresses in the 192.168.50.0/24 scope. Depending on the size of your network, you may ascertain whether you are there yet or not. Judging from the OP, I would guess not.

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This is not what (MS-DHCP) superscopes are about. This is. –  the-wabbit May 30 at 7:46
1  
@syneticon-dj You are wrong, syneticon-dj. Read after Table 4.3, you will see that Microsoft Tech makes exactly my point above. Can I have my two points back, now? –  MariusMatutiae May 30 at 8:20
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I am not wrong, you have a misconception about superscopes which you've expressed in your answer above. But you surely can have the 2 points back if you clarify that superscopes are only useful for implementing multiple logical IP subnets in a single broadcast domain. Note that a vote, once casted, cannot be changed unless the answer has been edited since. –  the-wabbit May 30 at 8:37
    
BTW: there is a difference between a superscope including two IP /24 networks and a single /23 - for the first case your default router would need to have two IP addresses (one for each subnet) and need to route traffic between the logical subnets, despite the hosts being technically able to communicate with each other directly. It is a pain in the bum to set up, manage and debug too, so I would not recommend using logical netting (and thus, using superscopes, too) to anyone now that VLANs are implemented all over. –  the-wabbit May 30 at 8:43
    
@syneticon-dj Not suggesting that a superscope with two subnets and a /23 subnet are the same: I am saying that in the OP's network there is no client initially with an IP address in the second scope, so that, so long as the first subnet has enough addresses, no address will be given in the second scope. In a real superscope, instead, one of the DHCP servers is actively dishing out IP addresses in the second scope even though the address space of either scope is far from exhausted. Which is the reason why the OP did not see any address in the second scope, which is what puzzled him. –  MariusMatutiae May 30 at 8:53

I think the difference here is not having to re-ip all of the network devices. The router can route all packets over a VDOM interface (I believe) between the two networks if any communication across the scopes is required.

The physical router port becomes a point of failure but if all you need is more addresses and the network wasn't previously designed to be extendable maybe a super scope isn't a horrible option while you plan for a total re-IP.

Additionally couldn't you use the super scope to slowly migrate into a new IP scheme? I think so.

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