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New Member

Aironet 1250 AP Question(s)

Good morning,

We purchased and installed the aforementioned access point device after being informed by our vendor that it could serve DHCP addresses to our wi-fi customers, supply a superior connection range over our pre-existing routers and offered more security, as well. While the feature list seems impressive I am struggling to find any options to allow the device to serve DHCP addresses. While I realize most AP's do not act as a DHCP server in the way a typical "router" does, we were assured that this rather pricy unit would meet all of our needs and then some. I've looked up the documentation for the unit and the only real information I can find regarding DHCP is associated with connecting via CLI to configure Option 43 to create a DHCP address pool. My concerns with this verbage is that it appears to be related to an address pool for various AP's to connect to rather than the AP serving a pool of DHCP addresses for customer wi-fi connections.

Long story short, is it possible to have this unit act as a full service router or were we fleeced by our vendor? If it is possible, is the CLI method the only way configuration of this option is attainable? Any information would be greatly appreciated.

Thanks in advance,

Gabe

10 REPLIES

Aironet 1250 AP Question(s)

If you want enable DHCP server on your Aironet use these commands:

ip dhcp pool POOL_NAME

   network 192.168.40.0 255.255.255.0

   default-router 192.168.40.1

   dns-server 192.168.40.1

You can use "ip dhcp excluded-address" to exclude an IP range.

The Aironet doesn't support NAT. So you must use a router or firewall for this.

Regards.

New Member

Re: Aironet 1250 AP Question(s)

Thank you for the reply! I'm going to try this out in the next few minutes and will post back if successful and tag as answered.

Edit: Didn't seem to work. I can't connect to the device due to not being given an address. I connected via Putty enter the admin user id and pw and then went into configure terminal. At that point I entered in the commands you provided and CTRL+Z'ed when finished. I am completely new to the CLI interface and after some other reading, it seems like I need to save the settings. Is that why this didn't work or does this change require a config file save?

Re: Aironet 1250 AP Question(s)

I tested this config on my Aironet 1240 but it should work also with 1250 model.

This is the aspected behavior:

AP1#

AP1#conf t

Enter configuration commands, one per line.  End with CNTL/Z.

AP1(config)#ip dhcp pool DHCP

AP1(dhcp-config)#   network 192.168.40.0 255.255.255.0

AP1(dhcp-config)#   default-router 192.168.40.1

AP1(dhcp-config)#   dns-server 192.168.40.1

AP1(dhcp-config)#exit

AP1(config)#exit

AP1#write

Building configuration...

[OK]

After that you can check the DHCP status with this command:

AP1#sh dhcp server

   DHCP server: ANY (255.255.255.255)

    Leases:   0

    Offers:   0      Requests: 0     Acks: 0     Naks: 0

    Declines: 0      Releases: 0     Bad:  0

To be sure that the DHCP daemon is running use this command:

AP1#conf t

Enter configuration commands, one per line.  End with CNTL/Z.

AP1(config)#service dhcp

AP1(config)#exit

AP1#write

AP1#show processes | i DHCP|dhcp

If you want check the service you can debug DHCP requests:

AP1#conf t

AP1#term mon

AP1#debug dhcp detail

to stop the debug use "undebug all"

output axample:

Oct 31 08:22:34.138 EDT: DHCP Offer Message   Offered Address: 10.2.173.14

Oct 31 08:22:34.138 EDT: DHCP: Lease Seconds: 43200

Oct 31 08:22:34.138 EDT: DHCP: Server ID Option: 10.2.250.21

Oct 31 08:22:34.138 EDT: DHCP: offer received from 10.2.250.21

Oct 31 08:22:34.138 EDT: DHCP: SRequest attempt # 1 for entry:

Regards.

New Member

Re: Aironet 1250 AP Question(s)

Daniele,

Here's where I'm at running a debug after trying to connect to the device. It is broadcasting fine but still not handing out an address;

IceArena#term mon

IceArena#debug dhcp detail

DHCP client activity debugging is on (detailed)

IceArena#

*Mar 12 18:23:35.881: %DOT11-6-ASSOC: Interface Dot11Radio1, Station   38e7.d869.1374 Associated KEY_MGMT[NONE]

*Mar 12 18:24:06.957: %DOT11-6-DISASSOC: Interface Dot11Radio1, Deauthenticating Station 38e7.d869.1374 Reason: Sending station has left the BSS

*Mar 12 18:24:12.045: %DOT11-6-ASSOC: Interface Dot11Radio1, Station   38e7.d869.1374 Associated KEY_MGMT[NONE]

This is as much info as it gives me when trying to connect and failing to receive an address from the unit. Is there a way I can see more specific debug detail?

Re: Aironet 1250 AP Question(s)

This is the note about DHCP server reported on the CISCO IOS Software Configuration Guide:

Configuring DHCP Service

Setting up the DHCP Server

By default, access points are configured to receive IP settings from a  DHCP server on your network. You can also configure an access point to  act as a DHCP server to assign IP settings to devices on both your wired  and wireless LANs.

The access point becomes a mini-DHCP server by default when it is  configured with factory default settings and it cannot receive IP  settings from a DHCP server. As a mini-DHCP server, the access point  provides up to 20 IP addresses between 10.0.0.11 and 10.0.0.30 to a PC  connected to its Ethernet port and to wireless client devices configured  to use no SSID, and with all security settings disabled. The mini-DHCP  server feature is disabled automatically when you assign a static IP  address to the access point. Because it has a console port to simplify  initial setup.


Note When  you configure the access point as a DHCP server, it assigns IP  addresses to devices on its subnet. The devices communicate with other  devices on the subnet but not beyond it. If data needs to be passed  beyond the subnet, you must assign a default router. The IP address of  the default router should be on the same subnet as the access point  configured as the DHCP server.


For detailed information on DHCP-related commands and options, refer to the Configuring DHCP chapter in the Cisco IOS IP Configuration Guide, Release 12.3. Click this URL to browse to the "Configuring DHCP" chapter:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr_c/ipcprt1/1cfdhcp.htm

Beginning in privileged EXEC mode, follow these steps to configure an  access point to provide DHCP service and specify a default router:


Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

ip dhcp excluded-address low_address [ high_address ]

Exclude the wireless device IP address from the range of addresses the  wireless device assigns. Enter the IP address in four groups of  characters, such as 10.91.6.158.

the wireless device assumes that all IP addresses in a DHCP address pool  subnet are available for assigning to DHCP clients. You must specify  the IP addresses that the DHCP Server should not assign to clients.

(Optional) To enter a range of excluded addresses, enter the address at  the low end of the range followed by the address at the high end of the  range.

Step 3 

ip dhcp pool pool_name

Create a name for the pool of IP addresses that the wireless device  assigns in response to DHCP requests, and enter DHCP configuration mode.

Step 4 

network subnet_number
[ mask | prefix-length ]

Assign the subnet number for the address pool. The wireless device assigns IP addresses within this subnet.

(Optional) Assign a subnet mask for the address pool, or specify the  number of bits that comprise the address prefix. The prefix is an  alternative way of assigning the network mask. The prefix length must be  preceded by a forward slash (/).

Step 5 

lease { days [ hours ] [ minutes ] |
infinite }

Configure the duration of the lease for IP addresses assigned by the wireless device.

days—configure the lease duration in number of days

(optional) hours—configure the lease duration in number of hours

(optional) minutes—configure the lease duration in number of minutes

infinite—set the lease duration to infinite

Step 6 

default-router address [address2 ... address 8]

Specify the IP address of the default router for DHCP clients on the  subnet. One IP address is required; however, you can specify up to eight  addresses in one command line.

Step 7 

end

Return to privileged EXEC mode.

Step 8 

show running-config

Verify your entries.

Step 9 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Use the no form of these commands to return to default settings.

This example shows how to configure the wireless device as a DHCP  server, exclude a range of IP address, and assign a default router:

AP# configure terminal

AP(config)# ip dhcp excluded-address 172.16.1.1 172.16.1.20

AP(config)# ip dhcp pool wishbone

AP(dhcp-config)# network 172.16.1.0 255.255.255.0

AP(dhcp-config)# lease 10

AP(dhcp-config)# default-router 172.16.1.1

AP(dhcp-config)# end

Monitoring and Maintaining the DHCP Server Access Point

These sections describe commands you can use to monitor and maintain the DHCP server access point:

Show Commands

Clear Commands

Debug Command

Show Commands

In Exec mode, enter the commands in Table 5-2 to display information about the wireless device as DHCP server.

Table 5-2     Show Commands for DHCP Server 

Command
Purpose

show ip dhcp conflict [ address ]

Displays a list of all address conflicts recorded by a specific DHCP  Server. Enter the wireless device IP address to show conflicts recorded  by the wireless device.

show ip dhcp database [ url ]

Displays recent activity on the DHCP database.

Note Use this command in privileged EXEC mode.

show ip dhcp server statistics

Displays count information about server statistics and messages sent and received.

Clear Commands

In privileged Exec mode, use the commands in Table 5-3 to clear DHCP server variables.

Table 5-3     Clear Commands for DHCP Server

Command
Purpose

clear ip dhcp binding
{ address | * }

Deletes an automatic address binding from the DHCP database. Specifying  the address argument clears the automatic binding for a specific  (client) IP address. Specifying an asterisk (*) clears all automatic bindings.

clear ip dhcp conflict
{ address | * }

Clears an address conflict from the DHCP database. Specifying the  address argument clears the conflict for a specific IP address.  Specifying an asterisk (*) clears conflicts for all addresses.

clear ip dhcp server statistics

Resets all DHCP Server counters to 0.

Debug Command

To enable DHCP server debugging, use this command in privileged EXEC mode:

debug ip dhcp server { events | packets | linkage }

Use the no form of the command to disable debugging for the wireless device DHCP server.

Try to follow the description and let me know the result.

Regards.

Hall of Fame Super Gold

Aironet 1250 AP Question(s)

First question, before getting the DHCP, did you set up an SSID with (for example) an OPEN authentication?

I mean if the clients can't connect to your SSID then DHCP is the least of your problem.

New Member

Aironet 1250 AP Question(s)

A valid question and yes, it's broadcasting the SSID as open auth. I can see it and try to connect to it, it just never gets around to issuing the address. Starting over again today to see if I get any further.

Hall of Fame Super Gold

Aironet 1250 AP Question(s)

Is "DHCP override" ticked or disabled on the SSID?

New Member

Re: Aironet 1250 AP Question(s)

This definitely works on an Autonomous AP as its how we allocate an address to our clients when doing wireless site surveys.

A few simple questions so to help you further

1. What is the network that you want to allocate to the wireless client

2. What is the IP address of the BVI1 interface?

3. Have you left the config VLAN free except for the default VLAN 1?

Can you also attach a copy of your current config?

HTH

Sent from Cisco Technical Support iPhone App

New Member

Aironet 1250 AP Question(s)

Sorry for the delay in response. I was off for a few days and then when I returned our vendor was able to put is in touch with Cisco support. I actually discovered yesterday via support's troubleshooting efforts that this unit was defective. The radio was not working correctly and settings didn't seem to be getting saved, either. After support remoted in and did a full configuration via console, the unit still did not retain it's configuration settings which seems to be at the heart of this issue.

I appreciate all of your helpful replies.

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