DHCP pool to large. I want to shrink it.

Hi. So I have a DHCP Pool from say x.x.x.1 to x.x.x.200 buti want to reduce it to allow more static IP addresses at the top end so I want for example to change it to x.x.x.1 to x.x.x.170 to do this do I need to make a not of all the settings and delete the pool entirely and recreate the new pool, or is there which I would prefer to do, some way to shrink the pool, without blowing it away.
I'm paranoid and hate the idea of deleting it and creating a new pool, just in case. :)
Thanks

Along with Anders comments...
I'm not sure, but with NetWare one could adjust begin and end ranges for the DHCP pool... no? (Can't check). That option was gone with Linux (eDir integrated) DHCP services, but can still be done "under water".
If it's just the range and no real subnet changes... you can also edit the range using iManager or ConsoleOne (by looking at the values of the subnet pool in the "other" tab). Then reload the service. You should give the PC's some time (depending on lease time and how ofter PC's get rebooted) to get an assignment that's inside the new set range before handing out the addresses for static assignment.
As added note:
The export/import will work just as well, but a word of warning: with the Linux DHCP version you can lose certain info like class definitions and other little stuff. So it's always good to make note of the settings before doing that.
Cheers,
Willem

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Maximum no of DHCP pools on a WLC

Hi, I want to create a separate ip pool pool based on the WLAN, what the maximum no of DHCP pools allowed on a WLC.

Internal DHCP is only for small networks and lab use.
We do not recommend to use it for any large deployment, please use an external DHCP server instead.
This is documented:
The internal DHCP server was introduced initially for branch offices where an external DHCP server is not available. It is designed to support a small wireless network with less than ten APs that are on the same subnet.
It is not a full-blown general purpose DHCP server. It only supports limited functionality and will not scale in a larger deployment.
http://www.cisco.com/c/en/us/support/docs/wireless/4400-series-wireless-lan-controllers/110865-dhcp-wlc.html#Internal-DHCP
While you can configure multiple DHCP pools and it can work fine for some time, in my experience I have seen this internal DHCP server stop leasing IP address with 2 or 3 class C networks configured.
My recommendation, use an external DHCP server.

DHCP pools for LWAP's with multiple models

I have 2 different AP models (1130's & 1140's) for which I want to create a DHCP pool on a core layer 3 switch with an Option 43 pointing to the Wireless LAN Controller. In conjunction with the Option 43 entry however, I need to specify the AP type as an ASCII string in the Option 60 parameter. Problem is, how can this be done for multiple ASCII strings; ie. multiple AP models? The DHCP pool option 60 entry only allows for one string and you can only enter one option 60 command per DHCP pool. Surely it is common to have more than one AP model and that this can be done without having to resort to multiple DHCP pools (one for every model)?
Can anyone shed some light on this for me please? Would be much apprciated as I've come up blank on CCO documentation!

I usually just stage the AP first to join a WLC and to make sure it works prior to installing it. Pllace it on the same submnet as the management and let it join and then set the primary, secondary and or tertiary. Then you can move it to any vlan you want. If you want to use DHCP Option or DNS, then you should know that if for example it is an RCVK IOS previous to capwap it will only do LWAPP. Once it joins to the WLC in LWAPP it takes a new IOS the unit will do CAPWAP.
As an example 1140 have an RCVK IOS that only run CAPWAP, so it should only do CAPWAP:
CISCO-LWAPP-CONTROLLER and CISCO-CAPWAP-CONTROLLER
Create two A records both pointing to the same controller if you want to use DNS.
DHCP Option 43:
DHCP Option 43 is limited to one access point type per DHCP pool. You must configure a separate DHCP pool for each access point type.
http://www.cisco.com/en/US/docs/wireless/access_point/1140/quick/guide/ap1140getstart.html#wp37440

DHCP Pool option question

adm-r1#sh run | sec dhcp
ip dhcp relay information option
ip dhcp bootp ignore
ip dhcp excluded-address 10.1.5.1 10.1.5.99
ip dhcp excluded-address 10.1.5.200 10.1.5.254
ip dhcp pool XXXXXXXXXXXXXXXXXXXX
network 10.1.5.0 255.255.255.0
default-router 10.1.5.1
dns-server 10.1.100.22 10.1.100.36 10.1.100.249
domain-name XXXXXXXXXXXXXXXXXXXXX
option 43 ip 10.1.5.100 10.1.5.199
option 60 ip 10.1.5.100 10.1.5.199
CUT
The customer here wanted to set an option 43 and 60 to dhcp adresses in this local pool.
What I am wondering is if the option command I have set works like the excluded addresses command does. Aka setting the option in range from .100 to .199?
I also added the ip dhcp relay information option to the config.
Other suggestions for this?
Haven't really set up many dhcp pools with option before. The customer's goal is to get autodiscovery going on their end.
My apologies if this question is posted in the wrong community, I found something with the word "LAN" and went for it.
/Erik

This may be a little late, but to help people in the future, I'm posting my working config
ip dhcp pool Solo
option 119 hex 0563.6973.636f.0363.6f6d.0002.636f.0275.6b00
This has to two domains, cisco.com and co.uk.
05 length in hex
00 null route label per RFC 1035. This goes at the end of each domain name.
63 ascii hex value of character
05636973636f03636f6d0002636f02756b00
05 C I S C O 03 C O M 0002 CO 02U K00
Yours would be configured as
option 119 0e6c6f7475732d696e7465726e616c02636f02756b0004636f7270056c6f63616c00
lotus-internal co uk corp local

DHCP Pool - DNS Search list - Option 119

Hello Experts
I've configured a DHCP Pool for a customer who wants the router to also give out a couple of dns suffixes to the clients.
This is what I've done. Can you please advise how i can get it to work ?
ip dhcp pool LAN
   import all
   network 10.106.0.0 255.255.0.0
   default-router 10.106.20.10
   dns-server 10.101.10.14 10.102.10.14
   option 119 ascii "lotus-internal.co.uk,corp.local"
many thanks
aravind

This may be a little late, but to help people in the future, I'm posting my working config
ip dhcp pool Solo
   option 119 hex 0563.6973.636f.0363.6f6d.0002.636f.0275.6b00
This has to two domains, cisco.com and co.uk.
05 length in hex
00 null route label per RFC 1035. This goes at the end of each domain name.
63 ascii hex value of character
05636973636f03636f6d0002636f02756b00
05 C I S C O 03 C O M 0002 CO 02U K00
Yours would be configured as
option 119 0e6c6f7475732d696e7465726e616c02636f02756b0004636f7270056c6f63616c00
                         lotus-internal       co    uk            corp                 local

Resize DHCP pool

Hi All;
We are looking to shrink our DHCP pool for one of our subnets. The server is running SLES10SP3/OES2.0.3. Is there a way to do so? Or do I have to create a new pool right underneath it and delete the old one. Any caveats? The server sits in the same subnet as the pool it supports.

Originally Posted by jgooderham
Hi All;
We are looking to shrink our DHCP pool for one of our subnets. The server is running SLES10SP3/OES2.0.3. Is there a way to do so? Or do I have to create a new pool right underneath it and delete the old one. Any caveats? The server sits in the same subnet as the pool it supports.
You can try to chang it with ConsoleOne or iManager.
Under Objects browse to the dhcp-Object and change settings.
CU
Michael

DHCP pool on 3550

I am setting up a training network and wanted to know if i can set up the 3550 as a dhcp server. Do i just add the ip dhcp pool? And do i need to give one of the ports a static IP so that the other switches on the network can also pool addresses from the switch? Thank for any help.

3550 is a L3 switch. You can define SVI interfaces for each vlan you want to route. You can define DHCP pools for each vlan (subnet)
int vlan 1
ip add 172.16.1.1 255.255.255.0
int vlan 2
ip add 172.16.2.1 255.255.255.0
ip dhcp pool VLAN1
network 172.16.1.0 /24
default-router 172.16.1.1
dns <>
lease <>
wins <>
option
ip dhcp pool VLAN2
network 172.16.2.0 /24
default-router 172.16.2.1
dns <>
lease <>
wins <>
option
On other switches (if supported) you can set the management vlan (VLAN1) as follows
int vlan 1
ip address dhcp (not all switches will support this option)
Create trunks between other switches and the 3550 and trunk the required vlans between them.
Also use VTP if required, to propagate vlans into the rest of the network rather than trying to create the same vlan in the database of each switch.3550 can be the VTP server, all others can be VTP client.

DNS in DHCP Pool (Internal DNS issue)

I know that we can setup multiple DNS server under DHCP pool. But I like to make sure the order.
I have multiple branch offices.
Let us say that Branch 1 office has a router with 10.30.1.1 as default gateway.
Our internal DNS is 10.0.0.1 and 10.0.0.2 as Pri and Sec.
My order of DNS server is like below.
1. gateway
2. internal DNS
3. public DNS provided by ISP
I saw couple of issues that when I put internal DNS first. Particular situation is when IPsec is not working, users could not access internet through domain name because they had internal DNS which is not reachable.
But, when gateway is first order, I am not sure whether user are able to access internal website because gateway DNS doesn't have internal DNS records.
So, my question is that. what should be the best order for DNS setup under DHCP among default gateway, internal DNS and public DNS? Our current setup doesn't have even gateway address, it only has internal DNS addresses only.
ip dhcp pool ccp-pool1
network 10.30.1.0 255.255.255.0
domain-name test.org
default-router 10.30.1.1
netbios-name-server 10.30.1.1
dns-server 10.30.1.1 10.0.0.1 10.0.0.2 24.25.5.60

Thank you, Richard.
You are right. when I setup router IP for DNS server in DHCP pool. it did not work.
Let me ask regarding external DNS forwarding.
I like to know the process of exteranl DNS.
User --> Internal website --> OK with internal DNS
User --> External website --> Internal DNS forwarding to External DNS
We have our own external DNS (ns), in this case, if external DNS (ns) is down, every branch users are not able to resolve any external IP because internal DNS can't get reply from external DNS?
2nd question)
IPsec is split-tunneled, but in this case, every DNS request goes internal DNS which is located in HQ and goes back through IPsec? Usually Split tunnel doesn't go internet traffic through IPsec but internet directly.
3rd Question)
what is for ip name-server x.x.x.x when I setup ip name-server 8.8.8.8 and I tried to ping 8.8.8.8 from router, it didn't work. Am i missing something?
https://supportforums.cisco.com/thread/230711
Thanks for your time and knowledge.

If the switch itself is hosting the DHCP pool, can the switch still be configured to send a copy of the request to ISE?

ip dhcp pool POOL52
network 10.10.52.0 255.255.255.0
domain-name didata.ise
dns-server 10.10.50.11 10.10.50.1
default-router 10.10.52.1
option 43 ascii 10.10.50.100
lease 7
Interface Vlan52
description EmployeeVLAN-52
ip address 10.10.52.1 255.255.255.0
ip helper-address 10.10.50.10
In this case above, 10.10.50.10 is the ISE server...

Yes you can do that. just add secondary DHCP as "ip helper-address "ISE IP Address" ".

WLC 5508 Flexconnect dhcp request landing on wrong vlan/dhcp pool

Hi,
We've recently setup our 5508 to work with Flexconnect. The 5508's run on 8.0.100, they are setup redundant. On the remote site we've setup a local dhcp pool for the various WLAN's/VLAN's. The AP's have registered with the WLC succesfully.
We then setup the flexconnect groups, added the ap's and configured 1 vlan mapping to it's corresponding wlan id. Alsio setup the wlan, made it so it's using flexconnect, bound it to the interface which will allow it to reach the local dhcp machine.
User can see the SSID, can login using the password, but they are awarded an ip addres from a different dhcp pool, meant for antoher vlan than the bonding in the flexconnect group is indicating.
When I check the local dhcp pool for bindings on the mac address of a machine I can see multiple bindings. At 1 point I had 3 bindings in different pools, 1 on the native vlan for the AP, 1 on the vlan it should have and 1 on another vlan which wasn't configured anywhere in the flexconnect setup.
Does anybody have a clue how and why this is happening?

Just to add to Salma... All your AP's in FlexConnect are most likely connected to a trunk port. Make sure the native Vlan is defined and the vlan's are allowed on the trunk port. Then you need to verify that the AP's native Vlan and WLAN to Vlan mappings are correct. Seems like you might have some AP's that are not defined properly and that's why users that connect to a WLAN is getting in the wrong subnet.
Scott

Can not create or modify DHCP pool in UC560

I can't create new or modify existing DHCP pool inside our UC560 by using CCA 3.2.3 version: Configurate->Routing->DHCP server. I always get error "invalid DHCP pool range. The default gateway IP address 192.168.2.1 must be within the range of the address excluded from the DHCP pool."
I check my DHCP exclude tab: I already have start IP: 192.168.2.1 and End IP 192.168.2.10.
I would like to know solution to modify my current DHCP pool or I can add new DHCP pool by using CCA. If I have to use CLI, please let me know how to do it.
Thanks
Jacques

Something with my configuration that CCA can't modify it.. It have to go through CLI
Thanks,
Jacque

Cannot make DHCP reservation out of the DHCP pool

Hello,
I foud a bug in the router:
I am using network 172.16.20.0 with subnet 255.255.252.0 wich means i can use IP adresses from 172.16.20.1 until 172.16.23.254.
When i setup my DHCP server on the router (from 172.16.20.1 to 172.16.20.100) i cannot make a DHCP reservation outside of this DHCP pool.
Is there a workaround or am i doing something wrong?
Thanks in advance.

This is normal networking standards. When a DHCP pool is set up, only reservations work with in this pool. You can set up static IPs out side this pool if needed. Which is recommended for printer, NAS and low priority devices.

DNS not resolving to new machines on network after increasing DHCP pool size

Hello,
I am having a very strange issue with connecting new machines to reach the internet.
We have a ASA 5505 which the previous tech configured the DHCP pool to 192.168.1.60 - 192.168.1.110
We ended up reaching our limit which I changed it to: 192.168.1.60 - 192.168.187
Then next day when I arrived to work, our DC was hung from windows updates. Once we got everything back up, every computer currently on the network can reach the internet/VPN tunnels etc. So (continuing with my day) I created a new server in a VM (Hyper-V)
I can ping everything internally (even the router) 192.168.1.1, but I cannot resolve DNS. I have configured a static IP, tried Dynamic IP.
I have looked for any ACL indicating to block outside the range of the old DHCP pool but no luck.
On my local maching I can ping the DNS addresses, but just not on the new server.
Can anyone point me in the right direction to where to look for this issue?

I ended up figuring out what the issue was.
Since it was in a Hyper-V VM. the hosting server had to be updated to SP1.
Once completed, and rebooted. The VM in question got an IP address.

I´m doing a design for presale, where I will need a router what support PAT for 500 or a little more of users, it not need any more features only static routing and dhcp pool for 500 users, can you help me for know what router recommend?

I´m doing a design for presale, where I will need a router what support PAT for 500 or a little more of users, it not need any more features only static routing and dhcp pool for 500 users, can you help me for know what router recommend?

What is your WAN speed currently and projected WAN speed in the next 3 years?

PC takes first IP from DHCP pool instead of binding (router 851)

I have configured main dhcp pool, and several bindings for my PCs. Whenever I connect PC it takes first available IP from main pool !!! What am I doing wrong??
ip dhcp pool local-pool
network 192.168.1.0 255.255.255.0
default-router 192.168.1.1
domain-name lan.local
dns-server 4.2.2.2 4.2.2.1
lease 0 0 1
ip dhcp pool Jurek
host 192.168.1.253 255.255.255.0
hardware-address 0000.aaaa.bbbb

Thanks Mikael.
Almost works with your advice.... I have to add 01 before MAC address, so when client-identifier is: 0100.00aa.aabb.bb then everything works perfectly !!
Thanks.

DHCP pool to large. I want to shrink it.

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