WLC dhcp debug

[Madura Malwatte]

I have a WLC 5520 running 8.5.131

I am trying to troubleshoot dhcp issue and want to know if I should be expecting more output in the dhcp debugs.

I have external dhcp servers configured on a dynamic interface on WLC.  And set dhcp proxy mode to global. 

However my clients do not get an IP addresses when connecting to the ssid.

I enabled:

debug dhcp messages

debug dhcp packets

I was expecting to see some output in the debug saying the WLC is forwarding the dhcp discover packet to the dhcp servers ip address, but don't see anything like that.

Instead this is what I see:

Anything wrong with the debug output? Or anything else I can check to debug this issue?

16:36:17.613: 64:5d:86:47:9d:34 DHCP received op BOOTREQUEST (1) (len 308,vlan 0, port 8, encap 0xec03, xid 0x37387e05)
16:36:17.613: 64:5d:86:47:9d:34 DHCP option len (including the magic cookie) 72
16:36:17.613: 64:5d:86:47:9d:34 DHCP option: message type = DHCP DISCOVER
16:36:17.613: 64:5d:86:47:9d:34 DHCP option: 61 (len 7) - skipping
16:36:17.613: 64:5d:86:47:9d:34 DHCP option: hostname = DESKTOP-A4G18T7 (len 15)
16:36:17.613: 64:5d:86:47:9d:34 DHCP option: vendor class id = MSFT 5.0 (len
16:36:17.613: 64:5d:86:47:9d:34 DHCP option: 55 (len 14) - skipping
16:36:17.613: 64:5d:86:47:9d:34 DHCP options end, len 72, actual 64
16:36:17.613: 64:5d:86:47:9d:34 DHCP (encap type 0xec03) mstype 0ff:ff:ff:ff:ff:ff
16:36:17.613: 64:5d:86:47:9d:34 DHCP intf:byod dhcp proxy mode global
16:36:17.613: 64:5d:86:47:9d:34 DHCP intf:byod dhcp proxy mode global
16:36:17.613: 64:5d:86:47:9d:34 DHCP processing DHCP DISCOVER (1)
16:36:17.613: 64:5d:86:47:9d:34 DHCP op: BOOTREQUEST, htype: Ethernet, hlen: 6, hops: 0
16:36:17.613: 64:5d:86:47:9d:34 DHCP xid: 0x57e3837 (92158007), secs: 0, flags: 0
16:36:17.613: 64:5d:86:47:9d:34 DHCP chaddr: 64:5d:86:47:9d:34
16:36:17.613: 64:5d:86:47:9d:34 DHCP ciaddr: 0.0.0.0, yiaddr: 0.0.0.0
16:36:17.613: 64:5d:86:47:9d:34 DHCP siaddr: 0.0.0.0, giaddr: 0.0.0.0
16:36:17.613: 64:5d:86:47:9d:34 DHCP Opt82 bridge mode insertion enabled, inserts opt82 if opt82 is enabled vlan=2509, datalen =18, optlen=64
16:36:17.613: 64:5d:86:47:9d:34 DHCP successfully bridged packet to DS
*ipv6SocketTask: 16:36:17.643: 64:5d:86:47:9d:34 DHCP intf:byod dhcp proxy mode global
*ipv6SocketTask: 16:36:18.643: 64:5d:86:47:9d:34 DHCP intf:byod dhcp proxy mode global
*apfOrphanSocketTask: 16:36:19.091: 64:5d:86:47:9d:34 In apfMsDhcpStateClear for station 64:5d:86:47:9d:34 to clear dhcp flag
*apfOrphanSocketTask: 16:36:19.091: 64:5d:86:47:9d:34 In apfRegisterIpAddrOnMscb_debug: regType=2 Invalid src IP address, 169.254.140.175 is part of reserved ip address range (caller apf_broff.c:232)
*apfOrphanSocketTask: 16:36:19.091: 64:5d:86:47:9d:34 IPv4 Addr: 169:254:140:175

*ipv6SocketTask: 16:36:20.659: 64:5d:86:47:9d:34 DHCP intf:byod dhcp proxy mode global
16:36:21.307: 64:5d:86:47:9d:34 DHCP received op BOOTREQUEST (1) (len 308,vlan 0, port 8, encap 0xec03, xid 0x37387e05)
16:36:21.307: 64:5d:86:47:9d:34 DHCP option len (including the magic cookie) 72
16:36:21.307: 64:5d:86:47:9d:34 DHCP option: message type = DHCP DISCOVER
16:36:21.307: 64:5d:86:47:9d:34 DHCP option: 61 (len 7) - skipping
16:36:21.307: 64:5d:86:47:9d:34 DHCP option: hostname = DESKTOP-A4G18T7 (len 15)
16:36:21.307: 64:5d:86:47:9d:34 DHCP option: vendor class id = MSFT 5.0 (len
16:36:21.307: 64:5d:86:47:9d:34 DHCP option: 55 (len 14) - skipping
16:36:21.307: 64:5d:86:47:9d:34 DHCP options end, len 72, actual 64
16:36:21.307: 64:5d:86:47:9d:34 DHCP (encap type 0xec03) mstype 0ff:ff:ff:ff:ff:ff
16:36:21.307: 64:5d:86:47:9d:34 DHCP intf:byod dhcp proxy mode global
16:36:21.307: 64:5d:86:47:9d:34 DHCP intf:byod dhcp proxy mode global
16:36:21.307: 64:5d:86:47:9d:34 DHCP processing DHCP DISCOVER (1)
16:36:21.307: 64:5d:86:47:9d:34 DHCP op: BOOTREQUEST, htype: Ethernet, hlen: 6, hops: 0
16:36:21.307: 64:5d:86:47:9d:34 DHCP xid: 0x57e3837 (92158007), secs: 0, flags: 0
16:36:21.307: 64:5d:86:47:9d:34 DHCP chaddr: 64:5d:86:47:9d:34
16:36:21.307: 64:5d:86:47:9d:34 DHCP ciaddr: 0.0.0.0, yiaddr: 0.0.0.0
16:36:21.307: 64:5d:86:47:9d:34 DHCP siaddr: 0.0.0.0, giaddr: 0.0.0.0
16:36:21.307: 64:5d:86:47:9d:34 DHCP Opt82 bridge mode insertion enabled, inserts opt82 if opt82 is enabled vlan=2509, datalen =18, optlen=64
16:36:21.307: 64:5d:86:47:9d:34 DHCP successfully bridged packet to DS
*ipv6SocketTask: 16:36:24.669: 64:5d:86:47:9d:34 DHCP intf:byod dhcp proxy mode global
d16:36:25.636: 64:5d:86:47:9d:34 DHCP received op BOOTREQUEST (1) (len 308,vlan 0, port 8, encap 0xec03, xid 0x37387e05)
16:36:25.636: 64:5d:86:47:9d:34 DHCP option len (including the magic cookie) 72
16:36:25.636: 64:5d:86:47:9d:34 DHCP option: message type = DHCP DISCOVER
16:36:25.636: 64:5d:86:47:9d:34 DHCP option: 61 (len 7) - skipping
16:36:25.636: 64:5d:86:47:9d:34 DHCP option: hostname = DESKTOP-A4G18T7 (len 15)
16:36:25.636: 64:5d:86:47:9d:34 DHCP option: vendor class id = MSFT 5.0 (len
16:36:25.636: 64:5d:86:47:9d:34 DHCP option: 55 (len 14) - skipping
16:36:25.636: 64:5d:86:47:9d:34 DHCP options end, len 72, actual 64
16:36:25.636: 64:5d:86:47:9d:34 DHCP (encap type 0xec03) mstype 0ff:ff:ff:ff:ff:ff
16:36:25.636: 64:5d:86:47:9d:34 DHCP intf:byod dhcp proxy mode global
16:36:25.636: 64:5d:86:47:9d:34 DHCP intf:byod dhcp proxy mode global
16:36:25.636: 64:5d:86:47:9d:34 DHCP processing DHCP DISCOVER (1)
16:36:25.637: 64:5d:86:47:9d:34 DHCP op: BOOTREQUEST, htype: Ethernet, hlen: 6, hops: 0
16:36:25.637: 64:5d:86:47:9d:34 DHCP xid: 0x57e3837 (92158007), secs: 4, flags: 0
16:36:25.637: 64:5d:86:47:9d:34 DHCP chaddr: 64:5d:86:47:9d:34
16:36:25.637: 64:5d:86:47:9d:34 DHCP ciaddr: 0.0.0.0, yiaddr: 0.0.0.0
16:36:25.637: 64:5d:86:47:9d:34 DHCP siaddr: 0.0.0.0, giaddr: 0.0.0.0
16:36:25.637: 64:5d:86:47:9d:34 DHCP Opt82 bridge mode insertion enabled, inserts opt82 if opt82 is enabled vlan=2509, datalen =18, optlen=64
ebug disable-all 16:36:25.637: 64:5d:86:47:9d:34 DHCP successfully bridged packet to DS
*ipv6SocketTask: 16:36:32.681: 64:5d:86:47:9d:34 DHCP intf:byod dhcp proxy mode global
16:36:33.396: 64:5d:86:47:9d:34 DHCP received op BOOTREQUEST (1) (len 308,vlan 0, port 8, encap 0xec03, xid 0x37387e05)
16:36:33.397: 64:5d:86:47:9d:34 DHCP option len (including the magic cookie) 72
16:36:33.397: 64:5d:86:47:9d:34 DHCP option: message type = DHCP DISCOVER
16:36:33.397: 64:5d:86:47:9d:34 DHCP option: 61 (len 7) - skipping
16:36:33.397: 64:5d:86:47:9d:34 DHCP option: hostname = DESKTOP-A4G18T7 (len 15)
16:36:33.397: 64:5d:86:47:9d:34 DHCP option: vendor class id = MSFT 5.0 (len
16:36:33.397: 64:5d:86:47:9d:34 DHCP option: 55 (len 14) - skipping
16:36:33.397: 64:5d:86:47:9d:34 DHCP options end, len 72, actual 64
16:36:33.397: 64:5d:86:47:9d:34 DHCP (encap type 0xec03) mstype 0ff:ff:ff:ff:ff:ff
16:36:33.397: 64:5d:86:47:9d:34 DHCP intf:byod dhcp proxy mode global
16:36:33.397: 64:5d:86:47:9d:34 DHCP intf:byod dhcp proxy mode global
16:36:33.397: 64:5d:86:47:9d:34 DHCP processing DHCP DISCOVER (1)
16:36:33.397: 64:5d:86:47:9d:34 DHCP op: BOOTREQUEST, htype: Ethernet, hlen: 6, hops: 0
16:36:33.397: 64:5d:86:47:9d:34 DHCP xid: 0x57e3837 (92158007), secs: 12, flags: 0
16:36:33.397: 64:5d:86:47:9d:34 DHCP chaddr: 64:5d:86:47:9d:34
16:36:33.397: 64:5d:86:47:9d:34 DHCP ciaddr: 0.0.0.0, yiaddr: 0.0.0.0
16:36:33.397: 64:5d:86:47:9d:34 DHCP siaddr: 0.0.0.0, giaddr: 0.0.0.0
16:36:33.397: 64:5d:86:47:9d:34 DHCP Opt82 bridge mode insertion enabled, inserts opt82 if opt82 is enabled vlan=2509, datalen =18, optlen=64
16:36:33.397: 64:5d:86:47:9d:34 DHCP successfully bridged packet to DS

[balaji.bandi]

here is the good reference document, can you tell us what is VLAN 2509 ?

https://www.cisco.com/c/en/us/support/docs/wireless/4400-series-wireless-lan-controllers/110865-dhcp-wlc.html

[Madura Malwatte]

vlan 2509 is tied to the dynamic interface I created on the WLC called "byod". Its central switching so everything gets tunnelled from AP to WLC and comes out on the byod interface subnet. User dhcp scope is from the same vlan/subnet as the byod interface.

I did have a quick glance over that document earlier. Looks like the debugs saying its in bridged mode - "DHCP successfully bridged packet to DS" ? But the interface config on WLC I have proxy mode global.

Have I misconfigured something?

[balaji.bandi]

Since wqe do not have the configuration posted it is hard to tell what was the issue. if you think as per document you missing some config, please change and test it. (hopefully this is test environment).

[patoberli]

Can your WLC management interface reach the DHCP server (the one you configured on the dynamic interface) with ports udp/67 and udp/68?

[Madura Malwatte]

I was able to resolve this issue, the WLC interface was set to proxy mode global and I believe global was defined as bridging, hence why the debugs were saying "DHCP successfully bridged packet to DS". I changed the mode to proxy and DHCP worked fine.

[Scott Fella]

Proxy is used if the wlc is performing dhcp services or if you want to have the wlc proxy dhcp request. However, typically folks will have dhcp proxy disabled and have up helper address on the L3 interface. The difference is when a user runs an ipconfig /all, you will see the wlc as the dhcp in proxy enabled or you will see the external dhcp server with proxy disabled.

[patoberli]

Hi Scott

Thanks for this information.

In my installation is DHCP proxy since, like ever (WiSM 1), enabled, but I also have wired clients in the same VLANs and all L3 interfaces have DHCP helper configured.

If I understand you correctly, this is not (anymore) needed and I could safely disable the global DHCP Proxy function?

Thanks

Patrick

[Scott Fella]

It is not needed as long as you have the ip helpers which you would since wired and wireless are in the same subnet. Again, it’s a preference also. I know that when I use to have this enabled, some customers didn’t like that the controller was showing up as the dhcp server and thought that support would have a hard time troubleshooting.