topic Re: Cisco WLC 9800 DHCP option 82 in Wireless

Cisco WLC 9800 DHCP option 82

AndreVal — Tue, 13 Sep 2022 06:19:54 GMT

Hi everyone,

My ISP requires to insert option 82 to every clients' DHCP request, so I was trying to configure that on my 9800-80 controller. No issues with the Remote Agent ID, I was able to insert eth_apmac and ssid. But I can't seem to find how to insert Agent Circuit ID. Documentation guides don't really say anything about that either. I'm also using AireOS WLCs and they insert circuit-id suboption with no problems (by default it's 00000000). Maybe it was abolished by Cisco and new WLCs won't insert circuit-id tag?

AireOS Cisco WLC 8540:

Old Cisco 8540

IOS-XE Cisco WLC 9800:

New Cisco 9800

Re: Cisco WLC 9800 DHCP option 82

Mark Elsen — Tue, 13 Sep 2022 07:21:07 GMT

- Ref : https://www.cisco.com/c/en/us/products/collateral/wireless/catalyst-9800-series-wireless-controllers/guide-c07-743627.html

>...

DHCP relay can be configured on the C9800 as well, but in that case a Layer 3 VLAN interface (SVI) needs to be configured to source such traffic. You may want to configure DHCP relay on the C9800 for multiple reasons. For example:

● The wireless team doesn’t have access to the next-hop switch configuration.

● You want to add option 82 information to the DHCP server.

The recommended way to configure DHCP relay on the Catalyst 9800 is under the “Advanced” tab of the SVI configuration: Configuration > Layer2 > VLAN; you can also define multiple DHCP servers and the option 82 relay settings:

Layer2 > VLAN" width="720" height="802" border="0">

Re: Cisco WLC 9800 DHCP option 82

AndreVal — Tue, 13 Sep 2022 08:03:22 GMT

Hello!

Thanks for replying, I tried that configuration but non of those options would insert Agent Circuit ID.

Re: Cisco WLC 9800 DHCP option 82

Mark Elsen — Tue, 13 Sep 2022 09:32:49 GMT

- Check if this document contains extra info's : https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/config-guide/b_wl_16_10_cg/dhcp-option82.html

Re: Cisco WLC 9800 DHCP option 82

AndreVal — Tue, 13 Sep 2022 11:55:35 GMT

Seen that too, they do mention Circuit id there, but nothing related to the specific configuration.

The Circuit ID suboption includes information that is specific to the circuit the request came in on. This suboption is an identifier that is specific to the relay agent. Thus, the circuit that is described will vary depending on the relay agent.

Re: Cisco WLC 9800 DHCP option 82

Mark Elsen — Tue, 13 Sep 2022 16:03:13 GMT

- Note 100% sure that the 9800 can do it , attached you will output from the feature navigator https://cfnng.cisco.com/browse/switching/features , for DHCP Option 82 Configurable Circuit ID and Remote ID

Re: Cisco WLC 9800 DHCP option 82

MHM Cisco World — Tue, 13 Sep 2022 18:11:17 GMT

As I know the ssid is the circuit-id for wireless
and port/vlan is the the circuit-id for wire

Re: Cisco WLC 9800 DHCP option 82

AndreVal — Tue, 13 Sep 2022 19:52:07 GMT

ssid goes to Remote Agent ID, while circuit-id was always fixed for WLCs - 00000000.

Re: Cisco WLC 9800 DHCP option 82

AndreVal — Tue, 13 Sep 2022 19:55:02 GMT

thanks for the document, but I even tried to upgrade to the latest IOS-XE they have (17.09.01) but still nothing, this is the best result I could get (everything but circuit-id haha):

Re: Cisco WLC 9800 DHCP option 82

MHM Cisco World — Tue, 13 Sep 2022 21:28:12 GMT

https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/config-guide/b_wl_16_10_cg/dhcp-option82.html

this guide
we can config WLC Op82
RID <<- this work for you
Circuit-id << guide not mention it
can you use instead of circuit-id the subscriber-ID ?

Re: Cisco WLC 9800 DHCP option 82

Rich R — Wed, 14 Sep 2022 10:42:40 GMT

Although https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/17-9/config-guide/b_wl_17_9_cg/m_pol_dhcp_option82_vewlc.html says this in the intro info:
"This option works by setting two suboptions:

Circuit ID
Remote ID

The Circuit ID suboption includes information that is specific to the circuit the request came in on."
I don't think they support Circuit ID on 9800 so far. That will need a feature request through TAC and your account team (if they don't already have one). We managed to get a number of these raised as bugs (sev 3 rather than sev 6) on the basis of providing feature parity with AireOS because they were eager to help migrate customers off AireOS. Not sure if they'll still be receptive to that but you can try. Assuming they accept it as a feature parity bug then best you can hope for is for it to be included in 17.10.1 and if you're really persuasive they might back-port it to 17.9 for you.

Re: Cisco WLC 9800 DHCP option 82

AndreVal — Wed, 14 Sep 2022 19:04:20 GMT

RID didn't really help here too. I suppose subscriber-id is the only option for us here and I should talk to ISP about using that instead.

Re: Cisco WLC 9800 DHCP option 82

AndreVal — Wed, 14 Sep 2022 19:06:34 GMT

Yep, seems like feature request is the way. But aside that ISP thing I can't imagine using it somewhere else. I think I'll talk to them first and ask about other options first. Anyway, thanks for your help!