topic Re: IP DNS query in Wireless

IP DNS query

WhozScott — Fri, 15 Apr 2022 01:34:10 GMT

Hello, I have an issue with my AP 3802i in the Discovery State. I want to say I'm new to networking stuff just learning things.

Here is my issue

[*11/09/2018 05:27:20.1838] CAPWAP State: Init
[*11/09/2018 05:27:20.1843]
[*11/09/2018 05:27:20.1843] Config not found, PNP is required, Starting PNP
[*11/09/2018 05:27:20.1843]
[*11/09/2018 05:27:24.0065] PNP:Server not reachable, Start CAPWAP Discovery
[*11/09/2018 05:27:24.0068]
[*11/09/2018 05:27:24.0068] CAPWAP State: Discovery
[*11/09/2018 05:27:24.0076] IP DNS query for CISCO-CAPWAP-CONTROLLER.SuperRouter.gg
[*11/09/2018 05:27:24.0115] Discovery Request sent to 255.255.255.255, discovery type UNKNOWN(0)
[*11/09/2018 05:27:24.0127] Discovery Request sent to ff01::18c, discovery type UNKNOWN(0)

I'm running a PFSence sever

Re: IP DNS query

Flavio Miranda — Fri, 15 Apr 2022 13:03:11 GMT

This is not an issue actually. Cisco Access Point in capwap mode has a script that tells him to search for an Wireless Lan controller as soon as the AP come up.

It tries to find the WLC using DHCP option 82, DNS resolution for CISCO-CAPWAP-CONTROLLER.domain and direct broadcast.

If one of this method sucessed, then, it discover the WLC Ip address and tries to join the WLC.

Now, with SDA, we can see that cisco added a new way which is PnP:

Config not found,

PNP is required, Starting PNP
PNP:Server not reachable

But, you dont have PNP server either. PNP server could be the DNA Center for SDA.

Then it continue:

CAPWAP State: Discovery
IP DNS query for CISCO-CAPWAP-CONTROLLER.SuperRouter.gg - Try to resolve this name and gets WLC ip address

Discovery Request sent to 255.255.255.255, discovery type UNKNOWN(0) (Try broadcast mode)

Here it tries to reach an IPV6 address. Maybe it got it from "CISCO-CAPWAP-CONTROLLER.SuperRouter.gg "
Discovery Request sent to ff01::18c, discovery type UNKNOWN(0)

All you have to do is prepare your environment:

"CISCO-CAPWAP-CONTROLLER.SuperRouter.gg" must resolve to the WLC ip address.

You can also add option 82 on the DHCP escope.

Re: IP DNS query

Rich R — Fri, 15 Apr 2022 14:19:55 GMT

@Flavio Miranda you're forgetting DHCP option 43

https://www.cisco.com/c/en/us/support/docs/wireless/5500-series-wireless-controllers/119286-lap-notjoin-wlc-tshoot.html#anc4

Re: IP DNS query

WhozScott — Fri, 15 Apr 2022 17:54:51 GMT

For my DHCP 43 what will I need to put in. I'm don't really understand how it work exactly.

For Option type 43
For Type select " "
For Value type " "

Re: IP DNS query

Flavio Miranda — Fri, 15 Apr 2022 18:55:40 GMT

Which DHCP server do you use?

Re: IP DNS query

WhozScott — Fri, 15 Apr 2022 19:57:48 GMT

I have a PFSense Flavio

Re: IP DNS query

Flavio Miranda — Sat, 16 Apr 2022 04:17:32 GMT

You must convert your controller IP address to HEX and add 01:04 to the beginning

To convert you can use any free tool on the internet

https://www.browserling.com/tools/ip-to-hex

Re: IP DNS query

WhozScott — Sat, 16 Apr 2022 04:58:28 GMT

We some how I fix the IPV6 at some point but still have the CISCO-CAPWAP-CONTROLLER.domain

I have done the 43 DHCP

I don't really understand how to set up a 82 DHCP

How would we go forward with setting that up

Also thank you for helping

[*11/09/2018 08:32:35.0364] Config not found, PNP is required, Starting PNP
[*11/09/2018 08:32:35.0364]
[*11/09/2018 08:32:38.7867] PNP:Server not reachable, Start CAPWAP Discovery
[*11/09/2018 08:32:38.7869]
[*11/09/2018 08:32:38.7869] CAPWAP State: Discovery
[*11/09/2018 08:32:38.7877] IP DNS query for CISCO-CAPWAP-CONTROLLER.SuperRouter.gg
[*11/09/2018 08:32:38.7917] Discovery Request sent to 255.255.255.255, discovery type UNKNOWN(0)

Re: IP DNS query

Flavio Miranda — Sat, 16 Apr 2022 10:09:07 GMT

Dont mind with option 82, I saw in a forum that pfsense does not support it.

But if you get dns or optiin 43 to work, must be enough.

Your dns is also the pfsense?

Re: IP DNS query

Rich R — Sat, 16 Apr 2022 11:16:44 GMT

Looking at https://docs.netgate.com/pfsense/en/latest/services/dhcp/ipv4.html (I've never used pfsense myself) I think the Type will be String and then your value is constructed as Flavio explained. So if your WLC IP address is 10.20.17.1 then the value will be f1:04:0a:14:11:01

https://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/97066-dhcp-option-43-00.html

Note: Corrected the prefix in the option 43 value. I copied what you typed @Flavio Miranda then realised that's wrong! The prefix is F1 followed by the number of octets following for the IP address then the value(s) of the IP address(es). So for one IP it's 04, for 2 IPs it's 08 etc.

Re: IP DNS query

WhozScott — Sun, 17 Apr 2022 01:19:31 GMT

Can I put the ap in autonomous? I hear that, that mode doesn't need a controller.

Re: IP DNS query

Rich R — Mon, 18 Apr 2022 10:24:30 GMT

No. IOS autonomous mode was last supported on the 802.11ac wave 1 APs. (1700, 2700, 3700) It does not exist since then.

On the wave 2 APs (including your 3802) Cisco introduced Mobility Express

https://www.cisco.com/c/en/us/solutions/enterprise-networks/mobility-express/index.html

https://www.cisco.com/c/en/us/td/docs/wireless/access_point/mob_exp/810/user_guide/b_ME_User_Guide_810/getg_started.html

https://software.cisco.com/download/home/286304536/type/286289839/release/8.10.171.0

This is the closest you get to "autonomous" on the 3802. The AP runs a compact version of the AireOS controller + the client serving AP function. It uses an IP address for each - 1 for the AP and 1 for the controller.

On the WiFi 6 catalyst 9000 series APs that has now been replaced by Embedded Wireless Controller on AP which is an AP version of the IOS-XE 9800 series controller which is actually much more full featured and in my opinion much better than ME. That still runs as controller + AP on the AP.

You could also consider using the 9800-CL controller running on a server Cisco Catalyst 9800-CL Wireless Controller for Cloud Data Sheet - Cisco

Re: IP DNS query

WhozScott — Mon, 18 Apr 2022 15:09:57 GMT

Could I use a Cisco Catalyst 1000 for my 3802i AP?

Re: IP DNS query

Rich R — Mon, 18 Apr 2022 20:28:09 GMT

As per https://www.cisco.com/c/en/us/products/collateral/wireless/aironet-3800-series-access-points/datasheet-c78-741682.html#Productspecifications

Input power requirements

● 802.3at PoE+, Cisco Universal Power over Ethernet (Cisco UPOE ^®)

● 802.3at power injector (AIR-PWRINJ6=)

● 50W power supply (AIR-PWR-50=)

The 1000 series datasheet https://www.cisco.com/c/en/us/products/collateral/switches/catalyst-1000-series-switches/nb-06-cat1k-ser-switch-ds-cte-en.html#Switchmodelsandconfigurations says they support POE+ so as long as you have a POE model of the switch with a 30W power budget for the AP port and CDP enabled, it should work.