Re: Multiple DHCP Scopes associated with VLANs



Hi bck,

~ Hi there,
~ First of all I'm from Switzerland. Therefore I'm pre-sorry for my bad
~ english.

No worries; it's much better than my French, German and Italian all
put together.

Let me explain that the Cisco Aironet APs have the following
configuration restriction: they may have exactly one IP address,
which IP address must be configured on interface BVI1. And, if
you have configured VLANs, BVI1 must be in the native VLAN.

So, to support IP traffic on multiple VLANs through the AP, the
AP's LAN interface must be connected (as an 802.1q trunk) to a
switch/router which is capable of routing (or otherwise talking
IP) on those VLANs.

It is possible to configure the DHCP server in the AP to serve
up addresses in multiple subnets; however, since the AP only has
an IP presence in the native VLAN, only the native VLAN scope will
work, UNLESS you have configured your interVLAN router to forward
the DHCP requests from non-native VLANs to the AP.

This article may help to explain matters:

Using VLANs with Cisco Aironet Wireless Equipment
http://www.cisco.com/en/US/products/hw/wireless/ps4570/products_configuration_example09186a00801d0815.shtml

Regards,

Aaron

---

~ My Problem is the following:
~ I'm trying to set up an Cisco 1231 AP (IOS 12.3). I configured (with
~ the GUI) an SSID 'intern' associated with the VLAN 250.
~ Now I got the two new virtual Interfaces Dot11radio0.250 and
~ FastEthernet0.250.
~ They are both in the 'bridge-group 250'. The physical interface
~ 'Dot11radio0' itself is in the 'Bridge-group 1' as well as the physical
~ interface FastEthernet0.
~
~ Now I configured these DHCP Scopes like that:
~
~ ip dhcp excluded-address 10.1.0.1 10.1.0.2
~ ip dhcp pool INTERN
~ network 10.1.0.0 /28
~ lease 10
~
~ ip dhcp excluded-address 10.0.0.1 10.0.0.3
~ ip dhcp pool DEFAULT
~ network 10.0.0.0 /28
~ lease 10
~
~ The following IP settings are set:
~ Dot11radio0: no ip address
~ Dot11radio0.250 : 10.1.0.1 /28
~ FastEthernet0: no ip address
~ FastEthernet0.250: no ip address
~ BVI 1: 10.0.0.2 /28
~
~ Now when I try to connect to the AP using the SSID 'intern', I get no
~ IP-Address.
~
~ I even tried to configure a BVI 250 interface with the IP-Address
~ 10.1.0.2 /28, it doesn't help. On the AP I turned on all 'debug ip dhcp
~ server' stuff and I don't even see a DHCPDISCOVER.
~ I also tried to abstract the Dot11radio0 interface from the
~ bridge-group 1 which isn't allowed as the AP says.
~
~ Probably I don't understand the Bridge-group thing very well but isn't
~ it inconsistent when the 'root' interface dot11radio0 is in
~ bridge-group 1 and the sub-if dot11radio0.250 itself is in bridge-group
~ 250?
~
~ I tried one more thing:
~ I did exactly the same configuration (in the GUI) without assigning the
~ SSID 'intern' to a VLAN. In that case I get an IP Address out of the
~ DEFAULT Pool.
~
~ ---
~
~ You wanna probably know where i actually want to get:
~ The target is to set up 3 SSIDs.
~ intern: clients that are allowed to communicate with the wired LAN and
~ the WAN
~ extern: clients that are allowed to communicate with the WAN
~ infrastructure: ssid-infrastructure to add a repeater-device later
~
~ To get that I think i need different address pools that i can easily
~ set up the access-lists.
~
~ Well, pre-thanks
~ greets bck

.



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