Access Points

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Occasional Contributor II

what is the use to place multiple vlan on a vatural ap

i am puzzled
what is the use to place multiple vlan on a Virtual ap ?
and if a Virtual ap have multiple vlan,which vlan will PC access to ?:confused:
Regular Contributor I

Re: what is the use to place multiple vlan on a vatural ap

If you are using a RADIUS server, you can redirect users to different VLANS based up on their authentication.

VLAN10 = Internet Only Access
VLAN20 = Internal Network Access

Student authenticates via the RADIUS server and is placed on VLAN10
Staff authenticates via the RADIUS server and is placed on VLAN20
Occasional Contributor II

Re: what is the use to place multiple vlan on a vatural ap

thank you for your reply,
but in some respects, I still do not understand

i think my pc should first connet to the virtual ap ,then the raduis can decide which vlan my pc access to . but the first time my pc connets to the virtual ap ,there are multiple vlans aready,at this point,how my pc chooses vlan?
Guru Elite

Multiple VLANs in Virtual APs


thank you for your reply,
but in some respects, I still do not understand

i think my pc should first connet to the virtual ap ,then the raduis can decide which vlan my pc access to . but the first time my pc connets to the virtual ap ,there are multiple vlans aready,at this point,how my pc chooses vlan?




If you put multiple VLANs in the virtual-ap parameter, users will be load-balanced into a number of Vlans instead of putting them into one single large VLAN. For example, if you have about 1000 users and you have 3 non-consecutive (noncontigous) /24 vlans that you want to put them into, you can just add those 3 non-contigous VLANs to the Virtual AP, and it will load balance all of your users into those three VLANs, instead of you having to create a single /22 to put them in.


Colin Joseph
Aruba Customer Engineering

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Occasional Contributor I

Re: what is the use to place multiple vlan on a vatural ap


i am puzzled
what is the use to place multiple vlan on a Virtual ap ?
and if a Virtual ap have multiple vlan,which vlan will PC access to ?:confused:


if you are running out of ip addresses you may apply multiple vlans. You are placed on the vlan based on your mac addresss.

mwblanche@widener.edu
Frequent Contributor II

Re: what is the use to place multiple vlan on a vatural ap


thank you for your reply,
but in some respects, I still do not understand

i think my pc should first connet to the virtual ap ,then the raduis can decide which vlan my pc access to . but the first time my pc connets to the virtual ap ,there are multiple vlans aready,at this point,how my pc chooses vlan?




You are placed on the vlan based on your mac addresss.
As stated by mwblanche, it's done by MAC address. It hashes the MAC then applies it to a VLAN. Unless you change the number of VLANs, that device should always be on the same VLAN. It doesn't "load balance" in the truest sense but this definitely helps spread the clients out.




We use it to make the broadcast domains smaller. With 3200+ clients in a 2-story school, we definitely need more than 1 VLAN!! We actually use 9 VLANs in those schools which (admittedly) might be overkill.

If you aren't in a real dense environment, it might not be needed. At least with Aruba, you have that flexibility (most other solutions are very painful in this area).

Contributor I

Re: what is the use to place multiple vlan on a vatural ap

To make it more clear, assume that you have 1000 users to use same SSID , two legacy method was (a) to create a /22 subnet and place to a single vlan say Vlan 100 , think about the size of broad cast domain size... (b) create multiple AP groups corresponding vlans and subnet .User will be placed to a Vlan and subnet based on the Aps they associates. In this case user roaming is a challenge.

With the arubaba's feature called "Vlan pool" you have the option to configure multiple vlans for a virtual group or a group of AP. Here logically all the client will be in the same subnet, but physically different. you can create small subnet size and can accommodate n number of users with same SSID .The system works by placing users in one of the VLANs in the pool. VLAN placement is done using the
user’s MAC address and running it through a hash algorithm. The output of this algorithm places the
user into one of the VLANs in the pool and ensures that the user is always placed into the same pool
during a roaming event. As the user associates with the next AP, their address is hashed. They are then
placed into the same VLAN on the new AP and can continue to use their existing IP address with no
break in their user sessions.
--
Shafi
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