Dhcp and different subnet design

We are trying to determine what is the best design for subnetting. We are moving into a building that has 4 floors. We are considering whether we should create class C subnet for each of the floors or just rather create a supernet of 4 continuous class C subnets. We are also using dhcp to assing IP to the user computers.
I am wondering if a user with his laptop disconnects from the network without releasing the IP and not turning the computer off and then goes to another floor and connects to the network, if the computer will automatically pick up a new IP in the appropriate subnet? We have windows 2000 and XP OS. I have heard some saying that it is automatic and others saying that you have to release and renew. I would appreciate if I can get a straight story from someone here. Thanks for the help.

How many switches are you looking at and how will they be connected? I think this will determine what the VLAN/IP Design will be.
Generally each logical access switch should have a unique user VLAN (and a Voice VLAN if you are deploying voice as well?). So for example if you have a 2950 with 48 ports then you should have an IP network with a /26 subnet mask (max 62-hosts). If you have a stack of two 3750's with 48-ports in each you should have a /25 subnet (max 128-hosts).
The issue you mention about DHCP should not be a problem; if the User moves his PC into a different network the DHCP request should be NAC'd by the DHCP server and he should be offered a new IP address in the correct subnet. Windows 2000 & XP detect the network connection so if you disconnect the cable it shuts the interface down. When you re-attach the cable Windows will attempt to keep the DHCP-assigned address by contacting the DHCP server, if you are on a different network the DHCP server will NAC the request and offer a new IP address. This used to be a problem with NT 4 and WIndows 95 as they didn't detect the network connection.
HTH
Andy

Similar Messages

Management and AP Manager on Different Subnets ...

Hello,
I am getting ready to implement a WLAN where the customer has designed the Management and AP Manger to be on different subnets. I have never done a WLAN implementation in this manner because per Cisco's config guide it states ...
"The AP-manager interface’s IP address must be different from the management interface’s IP address and may or may not be on the same subnet as the management interface. However, Cisco recommends that both interfaces be on the same subnet for optimum access point association."
So, I have always followed this recommendation and have always made the 2 interfaces be in the same subnet with IP's in sequential order. The config guide does say it'll work but I am just not sure what if anything do I have to do for this to work properly ... or if there is really a difference on how the process works doing it either way.
I plan on using LAG with Layer 3 ... most times I place the APs in the same wireless subnet/vlan as the management interface and AP manager but in this case or until I get more info it looks like they all may be in different subnets. So, if that's the case would I just need to use the Option 43 so the APs can find the WLC and if that is the case would I put the AP Manager IP or still use the WLC IP ... guess I would have that same question if I went the DNS route? Or do I still use the WLC IP address for the APs to join and at that point the AP Manager would take over the LWAPP communications?
Thanks for all your help in advance!

You should be using the WLC Management IP as documented in "Cisco 440X Series Wireless LAN Controllers Deployment Guide". Below is quoted from that document.
"The IP address of the WLC Management Interface should be used for Option 43 and DNS resolution of
CISCO-LWAPP-CONTROLLER.localdomain." For further information, see the section on "Understanding
Deployment Basics" beginning on page 13. Detailed information on using vendor specific DHCP Option 43
for WLC discovery is included in Appendices C, D, and E of this document.
Also there is no issue having the AP Manager and Management interfaces in different vlans although not recommended, just be sure to allow both vlans across the trunk to the WLC. I would also recommend placing your APs in different vlans than the WLC Mgmt/AP Mgr vlan. Cisco recommends having no more than 60-100 APs per vlan to minimize re-association problems in case of network failure.

Using DHCP with a cFP-20XX across a different subnet

I have a cFP-2010 that will work great when set up with a static IP or DHCP as long as it is on the same subnet. If I set it for DHCP then move it to a different subnet, MAX can no longer find it. Do I have to use a static IP when going across subnets, or is there something I'm missing?
Thanks,
Steve

Selmore,
Not 100% sure this will work for FieldPoint controllers, but for some
other NI controllers (e.g. CompactRIO) if you give a name to the
controller in MAX and set it to use DHCP, then when its IP address is
assigned by the DHCP server its name is registered as a DNS name. That
means you can use that name to communicate to it from a different
subnet. By using ping commands you should be able to demonstrate if
this works for FieldPoint or not; I believe it should.
Hope my answer is clear enough and helps.
JMota

WLC 5508 , AP client dhcp address different from WLAN interface VLAN subnet?

Hope the title makes sense, here's my situation: I have multiple businesses on 1 WLC 5508, there's a LAG to my core switch with seperate interfaces for each, broken up by vlans.
My question is: if i have a WLAN setup to use interface "Company A" which is vlan 10 with an ip of 10.0.1.5 which then points to 10.0.1.10 for dhcp.
Can the WLAN client connecting to the Company A WLAN use an IP in a different IP range?(192.168.1.10?) can the wlc route? from the perspective of the DHCP server where doers the request come from? (10.0.1.5?)
Can the DHCP server 10.0.10.10 on vlan 10 respond back with and ip on a different subnet to assign to the client to use and still be fully fonctioning? would the default gateway for the client need to be 10.0.1.5? So the clients ip would be 192.168.1.10 /24 with a gateway of 10.0.1.5 (ip adress fo vlan10 interface on WLC) And if multiple clients on the same subnet wanted to talk to each other woudl the WLC know how to route them to each other without passing through the default gateway?
Sorry if this is confusing I'm having a bit of a hard time explaining it in works, i can try and draw somethign up if it makes more sense.
thanks
Eric

I think if you want these clients to stick to a WLAN configured on a VLAN that has a different IP addressing you could configure your VLAN with the normal IP addressing then add on the SVI the 2nd IP_Class_default_gateway.
E.G.
Vlan 10
interface vlan 10
ip address 10.0.10.1 255.255.255.0
ip address 192.168.1.1 255.255.255.0 secondary
Clients that receive IP address from 192.168.1.0/24 network will be able to reach 192.168.1.1 and all traffic will pass right.

WLC and AP on different subnets

I would like to add a new AP to my existing controller. Currently i have about 15 AP's connected to a seperate mgt vlan for the AP's, vlan 10. It is trunked to the controller as well as the other user vlans like Private, Public, WVoIP etc. I have already started to implement EIGRP network wide instead of having a large layer 2 vlan'd network. At one of the newest locations i'm routing at, i have a new AP to connect. I'm trying to make sure this design will work before i implement it. So, i have a 3560 connected to my core 4506 with a layer 3 connection. EIGRP running as well. I plan to have the 3560 do intervlan routing with a voice vlan, data and wireless. The problem i see is how can i get the AP to talk with the controller since they are on a different subnets, over a metro E "WAN"? Any suggestions would be great.

As long as the LAP's have been primed locally first, that LAP will have the ip address of the WLC. If you want to attach the LAP to a different L3 subnet, then configure ip helper-address using the management ip of each wlc. then configure ip forward-protocol udp 12222 & ip forward-protocol udp 12223 globally on the L3 router. this along with the ip helper, will allow the LAP's to join the WLC on the other end.

WDS PXE DHCP, Clients on different subnet

Hello,
We are having a lot of trouble trying to get pxe imaging working from our WDS server on different subnets. We have an existing Zenworking imaging setup working as of right now, but WDS is causing more issues than I care to troubleshoot. I have read
blog after blog, forum post after forum post and everyone says just install it and it works! I guess we have run into some sort of problem that nobody else has.
Enviroment:
2x DC's, Server 2012 R2, both run DNS, 10.5.0.101, 10.5.0.102
1x DHCP Server, 2012 R2, 10.5.0.105
1x WDS Server, 2012 R2, 10.5.0.41
If I put a client on the same subnet as all of the servers it seems to work, except for the fact that it takes a while for the client to get an IP and continue to load wdsnbp.com. I would say around 20-30 seconds. In our zenworks enviroment it takes
no more than 1 second to get an IP. As for the dhcp server itself, clients receive normal dhcp offers instantly. So that part is working properly.
Now when I try an access the WDS pxe server from a different subnet other than the one that all of the servers are on, noting that I do have the ip helper address setup on our layer 3 switch:
interface Vlan2025
ip address 10.200.20.1 255.255.255.0
ip helper-address 10.5.0.105
ip helper-address 10.5.0.41
It always says failed to receive boot file. But as I said earlier, clients in windows receive dhcp leases from 10.5.0.105 without issue.
Setting the client options in the DHCP server with options 66 and 67 works sortof, but we found that it was unreliable and often finicky. Like having the system repeatedly ask to press f12, and even if you did press f12 it would still ask to press f12
again.
So I continued to do a wirehark packet capture on the port where the device was trying to get the dhcp/pxe info from the DHCP / WDS servers. The first packet here is from the DHCP server and the second is from the WDS server.
Bootstrap Protocol
Message type: Boot Reply (2)
Hardware type: Ethernet (0x01)
Hardware address length: 6
Hops: 0
Transaction ID: 0xd6c565d2
Seconds elapsed: 0
Bootp flags: 0x8000 (Broadcast)
Client IP address: 0.0.0.0 (0.0.0.0)
Your (client) IP address: 10.200.20.117 (10.200.20.117)
Next server IP address: 10.5.0.105 (10.5.0.105)
Relay agent IP address: 10.200.20.1 (10.200.20.1)
Client MAC address: Hewlett-_c5:65:d2 (78:e7:d1:c5:65:d2)
Client hardware address padding: 00000000000000000000
Server host name not given
Boot file name not given
Magic cookie: DHCP
Option: (53) DHCP Message Type
Length: 1
DHCP: Offer (2)
Option: (1) Subnet Mask
Length: 4
Subnet Mask: 255.255.255.0 (255.255.255.0)
Option: (58) Renewal Time Value
Length: 4
Renewal Time Value: (21600s) 6 hours
Option: (59) Rebinding Time Value
Length: 4
Rebinding Time Value: (37800s) 10 hours, 30 minutes
Option: (51) IP Address Lease Time
Length: 4
IP Address Lease Time: (43200s) 12 hours
Option: (54) DHCP Server Identifier
Length: 4
DHCP Server Identifier: 10.5.0.105 (10.5.0.105)
Option: (3) Router
Length: 4
Router: 10.200.20.1 (10.200.20.1)
Option: (6) Domain Name Server
Length: 8
Domain Name Server: 10.5.0.101 (10.5.0.101)
Domain Name Server: 10.5.0.102 (10.5.0.102)
Option: (15) Domain Name
Length: 8
Domain Name: domain.com
Option: (255) End
Option End: 255
Bootstrap Protocol
Message type: Boot Reply (2)
Hardware type: Ethernet (0x01)
Hardware address length: 6
Hops: 0
Transaction ID: 0xd2c565d2
Seconds elapsed: 4
Bootp flags: 0x8000 (Broadcast)
Client IP address: 0.0.0.0 (0.0.0.0)
Your (client) IP address: 0.0.0.0 (0.0.0.0)
Next server IP address: 10.5.0.41 (10.5.0.41)
Relay agent IP address: 10.200.20.1 (10.200.20.1)
Client MAC address: Hewlett-_c5:65:d2 (78:e7:d1:c5:65:d2)
Client hardware address padding: 00000000000000000000
Server host name: wds1.domain.com
Boot file name not given
Magic cookie: DHCP
Option: (54) DHCP Server Identifier
Length: 4
DHCP Server Identifier: 10.5.0.41 (10.5.0.41)
Option: (97) UUID/GUID-based Client Identifier
Length: 17
Client Identifier (UUID): eb8daa31-8e62-11df-bbd8-d1c565d278e7
Option: (60) Vendor class identifier
Length: 9
Vendor class identifier: PXEClient
Option: (53) DHCP Message Type
Length: 1
DHCP: Offer (2)
Option: (255) End
Option End: 255
What I find interesting is that the WDS server is not handing out a boot file name:
"Boot file name not given"
Could this be the reason why we receive the no boot file received error when trying to boot a client into pxe?
The other thing that I noticed was that the WDS server is also responding with the:
" Option: (60) Vendor class identifier
Length: 9
Vendor class identifier: PXEClient
Why would it be responding with this, when the dhcp is on a separate server. Is this option only if you have DHCP and WDS on the same server?
Any help would be appreciated as there has been too much time already spent on getting nowhere.
Thanks,
Dan.

Dan,
10 months later and not one reply... I'm having the same issue, did you ever figure this out? DHCP server is my Cisco Switch, WDS/PXE is on another network. The WDS and PXE is working fine as I can do so from the same network as the WDS/PXE
server. I can also get the WDS/PXE to work if I have a MS DHCP server on a different network and populate the option 66 and option 67. I cannot get this to work using Cisco ip helper-address for some reason.
Thanks,

IP and VIP adresses temporary on different subnets

I was wondering if it's possible to add a third node temporary on a different subnet ?
I mean.. now my two nodes have these IP: XXX.XXX.0.5 and XXX.XXX.0.6 , VIP are: XXX.XXX.7.15 and XXX.XXX.7.16
Is it possible to add a third node with IP YYY.YYY.0.7 and VIP YYY.YYY.7.17 ?
Of course they can ping each other and successfully use ssh equivalence...
Thanks.

Unfortunately not, the nature of the way VIPs work means that that must be on the same subnet throughout the cluster

Look different in Design view and Browser Preview

Why do it look different in Design view and Browser
Preview?

"MA_DAVIDLEE" <[email protected]> wrote in
message
news:e39mte$las$[email protected]..
> thank you for reply and the url is www.cipr.com.tw. you
can see the
> navigation position is different in Design view. Thank
you!
>
How could I see the Design view? Can you post a
screenshot?

Management and native Vlan in different subnet??

Can i have a management ip and native vlan in different subnet on a AIR-1242 and 2960 switch?
Native on Switch = 1.
Interface vlan 100 = 10.10.1.25X /24
BVI ip in vlan 100 = 10.10.1.25X /24
-HM-

Hi,
Thanks for the update..
Ok in short YES this can be done.. here is the AP configuration..
Step 1>> Configure the SSID and map it with respective Vlans..
Step 2>> Create the sub interafce int dot11 0.5 / int fa 0.5 (encapsulation dot1q 5 , bridge-group 5)and int dot11 0.6 / int fa 0.6(encapsulation dot1q 6 , bridge-group 6)
Step 3>> Create the sub interface 0.100 for both Radio and Fa and under this (encapsulation dot1q 100 native , bridge-group 1)
Step 4>> Make sure all the interafces are up and running and Try to ping the VLAN 100 interafce ip addr from the AP to verify.
lemme know if this answered your question..
Regards
Surendra
====
Please dont forget to rate the posts which answered your question and mark it as answered or was helpfull

Printing to a shared printer on a different subnet

I have 2 macs:
1 on a wired on subnet 1 (10.0.0.xxx) = SERVER
I have my Powerbook on a second (wireless) network (10.0.2.xxx) = CLIENT
The 10.0.2.xxx router is plugged into the 10.0.0.xxx router so I can see (ping and map drives on) the SERVER from the CLIENT
The problem I am having is I cannot see any shared printers on my SERVER because it am on a different subnet than the CLIENT.
Is there a way I can tell the CLIENT machine how to find the shared printer on the SERVER?
PowerMac G4 & Powerbook G4 Mac OS X (10.3.9)

Is there a reason you want to keep the two subnet arrangement?
The second router is what's preventing the connection.
Your easiest fix would be to change your use of the second router to wireless access point - where the second router's functions except wireless are turned off (No DHCP, no firewall, no NAT).
It is possible (depending on router setup functions) that you can use port forwarding to direct port 631 (IPP printer sharing) to the IP address of the wireless computer and get this working as is. Won't hurt to try. This would be on the 2nd router only.

Is it OK to have two SBS Servers with same name, on different subnets but connected over a VPN?

Hi Everyone,
I'm just about to connect up two SBS 2011 Servers with the same server name but on different subnets & domains over a VPN.
So for example both servers will have the name Server01, one would have an ip address of 192.168.85.5, the other 192.168.86.5, they both then would be connected over a VPN.
Can anyone foresee any issues with this configuration, like DNS & DHCP requests, adding new machines to the domain, mapping drives etc.
Many thanks,
Nick

Hi Larry & Strike First,
Thank you for your responses. I understand that this is an unusual situation. Basically I've recently taken over the IT support for this client. The client has just had a new phone system installed
& are asking if they can speak to each office internally, which can easily be done once I setup the VPN.
However I noticed whilst looking at this further that the Server names are the same, hence my question?
Am I right in saying that providing the workstations have a trust relationship with their own domain controllers through their individual domains on separate subnets, that hopefully there shouldn't be any DNS issues between the two domains and Servers?
I could build a new VM if you feel it would be better practice to do so?
Many thanks for your assistance,
Nick

Mac, WRT 54G, Can I access a Brother MFC9320 on two different subnets?

(home use) I have a USB server that I can access my USB printers on two different Subnets and I was wondering if I can do the same on the WRT54G. I use 192.xxx.xxx.x for internet use only and 198.xxx.xxx.x for every thing else, like file sharing, multiplayer games, etc. I just named the "Locations" to either "Internet" or "Games" (with games being used for everything else). With the USB server set to "ZerocConfig" I could access the USB printers on both. I could set the Printer up with a static IP Printer "Location" and then switch locations every time we wanted to print to it but I would like to save a step. It's not that big a deal for me but, having to "Remind" everyone else every time they wanted to print something on it, would get old. Don't want to hook the Brother up to the USB server if I have wireless. It's not the smallest thing in the world to find a place for it anyway.
I guess my other question would be, having the other subnet, is it more secure (from the internet) using it that way or is it just in my mind. I actually have the the family put their computers on a third "Blank" Location (no IP #) when they are just playing games, homework, etc.
Thanks,
Solved!
Go to Solution.

I'm guessing the reason i CAN use the USB printers on both subnets is because of the Keyspan USB server, which is hooked to the router, using it's own version of DHCP, (ZeroConfig)? I guess "ZeroConfig" is an open source type configuration. I use a subnet of 192.xxx.xxx.xxx for Internet browsing and I can print with the USB printers, and I use a subnet of 198.xx.xxx.x for everything else and I can still print from the USB printers with out changing anything else. It uses it's own IP numbers on ZeroConfig I guess and when the server is set to DHCP it uses the routers IP instead as then i can't print on the other subnet.
I guess it's not possible on the router to do it. That's what I was wondering, thanks.....

Hyperion Servers on Different Subnets

Our network engineers have designed a new scheme for our networkwhereby there will be different subnets for the web servers,application servers, and database servers. We are onHyperion System 9, our web server contains the Hyperion WASservices (planning, reporting, shared services, openldap, etc); ouressbase db and license server are on one database server, and SQLand the reports server (communications, scheduler, etc) are onanother server. In this new network scheme, the Hyperion webserver will be on a different subnet than the two database servers. Does anyone see any issues or know of any issues with thissetup? Thanks,Candy

Hi,
You can do this, but you have to use client-NAT (Source-NAT) to force the return traffic to pass back through the ACE. You also then need static routes in the ACE context to point at each server. PBR is an alternative approach but I have not implemented that in a live network. The important thing is that the ACE sees both sides of the conversation.
The following extract from a configuration shows the basic principle:
rserver host master
ip address 10.199.95.2
inservice
rserver host slave
ip address 10.199.38.68
inservice
serverfarm host FARM-web2-Master
description Serverfarm Master
probe PROBE-web2
rserver master
inservice
serverfarm host FARM-web2-Slave
description Serverfarm Slave
probe PROBE-web2
rserver slave
inservice
class-map match-any L4VIPCLASS
2 match virtual-address 10.199.80.12 tcp eq www
3 match virtual-address 10.199.80.12 tcp eq https
policy-map type management first-match REMOTE-MGMT-ALLOW-POLICY
class REMOTE-ACCESS
permit
policy-map type loadbalance first-match LB-POLICY
class class-default
serverfarm FARM-web2-Master backup FARM-web2-Slave
policy-map multi-match L4POLICY
class L4VIPCLASS
loadbalance vip inservice
loadbalance policy LB-POLICY
loadbalance vip icmp-reply active
loadbalance vip advertise
nat dynamic 1 vlan 384
service-policy input L4POLICY
interface vlan 383
description ACE-web2-Clientside
ip address 10.199.80.13 255.255.255.248
alias 10.199.80.12 255.255.255.248
peer ip address 10.199.80.14 255.255.255.248
access-group input ACL-IN
access-group output PERMIT-ALL
no shutdown
interface vlan 384
description ACE-web2-Serverside
ip address 10.199.80.18 255.255.255.240
alias 10.199.80.17 255.255.255.240
peer ip address 10.199.80.19 255.255.255.240
access-group input PERMIT-ALL
access-group output PERMIT-ALL
nat-pool 1 10.199.80.20 10.199.80.20 netmask 255.255.255.240 pat
no shutdown
ip route 0.0.0.0 0.0.0.0 10.199.80.9
ip route 10.199.95.2 255.255.255.255 10.199.80.21
ip route 10.199.38.68 255.255.255.255 10.199.80.21
HTH
Cathy

DHCP and WLC 4402 clients

Hi
Our scenario is that we are building a test rig-up prior to WLC deployment. We have a 4402 WLC with LAP1242s, Windows clients. The WLC is running v4.2.99 firmware.
Our problem is that the wireless clients are not collecting DHCP addresses.
The configuration is:
Base network address is 172.31.4.0 / 255.255.252.0.
WLC on 172.31.7.220 / .221.
DHCP server on 172.31.4.12
G/W on 172.31.4.1.
We are simulating the gateway with an ADSL router (not connected so no external traffic but at the moment that is the least of our troubles), and the DHCP server with a Cisco 805 router with only the Ethernet interface in use (the 805 permits us to configure a different D/G to the DHCP server).
We have a catalyst 2950 switch in the circuit which has no VLANs nor access-lists configured.
The wireless clients can associate to the LWAPs but do not collect an IP address.
Wired clients can collect DHCP addresses and ping the DHCP, GW and controller.
Can anyone help me understand what is going on here please and how to get the DHCP working?
We did use this configuration - exactly these boxes in fact - to configure a different WLC last week (different subnets though) and we were successful - but not now.
Thanks in advance

I see.
We are not using option 43 at all. The DHCP server is unchanged - the APs are using network broadcast to find the controller. As I posted above, the APs are contacting the controller without a problem, the clients are associating with the APs without a problem, only the clients weren't getting an IP adress.
The problem appeared to go away totally after I re-configured it with v4.1.185. It's in and working now so I won't be spending any more time on it.
While it would be interesting to try things out, these controllers are too expensive to have one lying around for long ;-)

DHCP and multiple interfaces

Is it better to list each machine and interface as a separate entry in 10.5.7 DHCP or make a single entry with multiple interfaces?
I am looking at grouping my Wireless AP, instead of having to list each one separately.
For example:
MAIN-MDF00-01
XX:XX:XX:XX:XX:XX 10.0.2.1
Or
MDF-AP
XX:XX:XX:XX:XX:XX 10.0.2.1
XX:XX:XX:YY:YY:YY 10.0.2.2

Joe,
Currently you cannot base the anchoring on the AP group. It is only based on the SSID.
Now, do you really need to split up the guest into different subnets? Or are you concerned about the AP groups?
If you truly need to break up the guest to different subnets, then you would need to create different SSID on the internal and anchor controller. Then on the anchor, link to the appropriate interface.
If you are concerned about the AP group, don't be. Just because you are using the AP group, doesn't meant that all the guest ssid can't link to the same interface, they can. You can even create a dummy interface on the internal WLC, so that if the anchoring doesn't work, they do not get an address.
Cheers,
Steve
If this helps you and/or answers your question please mark the question as "answered" and/or rate it, so other users can easily find it.

Dhcp and different subnet design

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