[c-nsp] WLC with DHCP relay not working on in VRF

[Nasir Shaikh]

Hi,

I encountered a problem whereby I have a  Guest-LAN placed in the VRF and a
guest tries to connect via a WLC which is configured as a dhcp-relay. The
guest does not get any IP address assigned by DHCP.

 

Apparently the DHCP server functionality does not work properly in the VRF
when a DHCP-relay is used, see below debug.

 

First I thought it might be a bug in 12.4(20)T3 on the 2851 and 3845 on
which I encountered the issue but had the same result on a 3945E running
15.1 so it seems on all IOS's

Problem does not occur when using autonomous APs.

 

WITH THE VRF we see the following debug info:

Dec  6 13:42:16.829 CET: DHCPD: Sending notification of DISCOVER:

Dec  6 13:42:16.829 CET:   DHCPD: htype 1 chaddr f87b.7a04.db2d

Dec  6 13:42:16.829 CET:   DHCPD: remote id 020a0000c0a80a02000300c0

Dec  6 13:42:16.829 CET:   DHCPD: circuit id 00000000

Dec  6 13:42:16.829 CET:   DHCPD: table id 1 = vrf VRF_Guest

Dec  6 13:42:16.829 CET: DHCPD: DHCPDISCOVER received from client
f87b.7a04.db2d through relay 192.168.9.193.

Dec  6 13:42:16.829 CET: DHCPD: Seeing if there is an internally specified
pool class:

Dec  6 13:42:16.829 CET:   DHCPD: htype 1 chaddr f87b.7a04.db2d

Dec  6 13:42:16.829 CET:   DHCPD: remote id 020a0000c0a80a02000300c0

Dec  6 13:42:16.829 CET:   DHCPD: circuit id 00000000

Dec  6 13:42:16.829 CET:   DHCPD: table id 1 = vrf VRF_Guest

Dec  6 13:42:16.829 CET: DHCPD: there is no address pool for 192.168.9.193.

 

WITHOUT THE VRF we see the following debug info:

Dec  6 14:46:05.413 CET: DHCPD: Sending notification of DISCOVER:

Dec  6 14:46:05.417 CET:   DHCPD: htype 1 chaddr f87b.7a04.db2d

Dec  6 14:46:05.417 CET:   DHCPD: remote id 020a0000c0a80a02000300c0

Dec  6 14:46:05.417 CET:   DHCPD: circuit id 00000000

Dec  6 14:46:05.417 CET: DHCPD: DHCPDISCOVER received from client
f87b.7a04.db2d through relay 192.168.9.193.

Dec  6 14:46:05.417 CET: DHCPD: Seeing if there is an internally specified
pool class:

Dec  6 14:46:05.417 CET:   DHCPD: htype 1 chaddr f87b.7a04.db2d

Dec  6 14:46:05.417 CET:   DHCPD: remote id 020a0000c0a80a02000300c0

Dec  6 14:46:05.417 CET:   DHCPD: circuit id 00000000

Dec  6 14:46:05.417 CET: DHCPD: Allocate an address without class
information (192.168.8.0)

Dec  6 14:46:07.417 CET: DHCPD: Adding binding to radix tree (192.168.8.3)

Dec  6 14:46:07.417 CET: DHCPD: Adding binding to hash tree

Dec  6 14:46:07.417 CET: DHCPD: assigned IP address 192.168.8.3 to client
f87b.7a04.db2d.

Dec  6 14:46:07.417 CET: DHCPD: Sending DHCPOFFER to client f87b.7a04.db2d
(192.168.8.3).

 

Config is straightforward.

ip dhcp pool Guests

vrf Guests

import all

network 192.168.8.0 255.255.252.0

default-router 192.168.10.1 

 dns-server 8.8.8.8 8.8.4.4

 lease 0 4

!

interface Vlan192

description Guest access Internet (ISP Speed = 120M)

ip forwarding vrf Guests

ip address 192.168.10.2 255.255.252.0

ip access-group 192 in

 

 

Any ideas?

 

Regards

 

Nasir