Dhcp running out of ips to dish out

[said07]

Greetings,

My one and only dhcp scope is running out of ips to distribute.
I saw on KB 255999 that one can perform:
Scope Extension
Resubnetting
Superscoping

Scope Extension is not an option because we already use the full range.
Resubnetting seems like lot of work because we have so many static ips on the floor.
We are left I guess with Superscoping.
Can anyone share his/her experience to help us through this one?

Thanks

 

[58sniper]

You need to be careful with supernettting or anything that puts more hosts in the same subnet. Broadcast traffic starts to get overwhelming. A good solution is to have servers and related equipment in their own subnet, and workstations in a different subnet. Not only does this result in more addresses, but you can configure the workstation firewalls to only communicate with the server subnet, which increases security.

Pat Richard MVP
Plan for performance, and capacity takes care of itself. Plan for capacity, and suffer poor performance.

http://www.ucblogs.net/blogs/exchange/

 

[said07]

Are you referring to vlans to be configured on the switches or something else that windows can do without touching the switches?

 

[kmcferrin]

Have you tried shortening the lease duration? If it is set for 7 days (I believe the default) and someone uses a wireless laptop for one day, that IP address is unavailable for the next 6 days. If that happens with any regularity then you can quickly run out of IP addresses in the pool. By shortening the lease duration you can mitigate the problem.

Then the next thing that I would do is create a new subnet with a new pool that matches, and subdivide the network. You might want to consider having all static IPs on one subnet and then use other subnets for DHCP.

Incidentally, what is consuming all of the static IPs? I usually only use those for servers, printers, and networking equipment, all of which I recommend being kept on a separate subnet from users.

________________________________________
CompTIA A+, Network+, Server+, Security+
MCTS:Windows 7
MCSE:Security 2003
MCITP:Server Administrator
MCITP:Enterprise Administrator
MCITP:Virtualization Administrator 2008 R2
Certified Quest vWorkspace Administrator

 

[said07]

kmcferrin: I even shortened my lease to just one day.
I have lot of servers, switches, network printers, Wifi Aps, Sans,.. and that's mostly in my static range. The rest is consumed by my workstations and machines on the floor. We are a manufacturing outlet.
I can create another subnet on my Dhcp but my knowledge is limited when it comes to routing.
How do I do that? By the way we have a layer 3 cisco 3750 amongthe swicthes. The rest are layer 2.
Thanks for taking the time to contribute.

 

[kmcferrin]

You definitely need separate subnets. Put all of the server/SAN/infrastructure stuff on one or more subnets, and then create a new subnet for the users. You can use the 3750 to route between the subnets. Just make sure that you put an IP for each subnet on the switch and specify those IPs as the default gateways for devices on the respective networks.

Unless you have some other router in your environment perhaps?

________________________________________
CompTIA A+, Network+, Server+, Security+
MCTS:Windows 7
MCSE:Security 2003
MCITP:Server Administrator
MCITP:Enterprise Administrator
MCITP:Virtualization Administrator 2008 R2
Certified Quest vWorkspace Administrator

 

[said07]

No router. Just the 3750. And that's what I am struggling with.
It is clear in my mind how to configure subinterfaces on a router's fa0/0 but on the 3750, which port to use is one question (I have two connected to other switches and configured as trunks, with ip route enabled- interface GigabitEthernet1/0/24 or interface GigabitEthernet1/0/28).
the other question would be how to configure the subinterfaces ?

 

[58sniper]

You'd probably get excellent answers in the Cisco switches forum.

Pat Richard MVP
Plan for performance, and capacity takes care of itself. Plan for capacity, and suffer poor performance.

http://www.ucblogs.net/blogs/exchange/

 

[said07]

IThanks 58sniper for the suggestion. I have posted the question there.