Subject: [eap] why authenticator is not on the access node?

From: "Alper Yegin" <[email-masked]>
Date: Tue, 8 Nov 2005 00:32:03 +0200

Hi Sam,
 
Continuing the discussion we had during the EAP WG...
 
Various mobile and wireless architectures place the authenticator (NAS)
on a centralized node instead of on each access node (e.g., IEEE 802.11
access point (AP), IEEE 802.16 base station(BS)).
 
This is mostly driven by practical deployment considerations.
Architectures like WiFi and WiMAX that need to support hundreds of AP/BS
and seamless mobility across them tend to include a centralized element
that manages the network access sessions of each mobile terminal.
Various services such as mobility management (L2 and L3), network
access, radio resources are controlled in that element.
 
Technically the NAS can be placed on the AP/BS, but given the high
number of these elements, and the need to coordinate sessions as mobile
stations move from one to other, a hierarchical model where all such
management functionalities are aggregated in a centralized server is
preferred.
 
I hope this clarifies the motivation behind the separation of NAS from
the access nodes.
 
Regards,
 
Alper

---

From: Matt Holdrege <[email-masked]>
Date: Tue, 08 Nov 2005 08:23:17 +0100

Perhaps in some architectures, but not all. In large mesh networks it is 
(or so far empirical evidence suggests) that it is better to have the NAS 
at each radio. So please keep that in mind.

-Matt

At 11:32 PM 11/7/2005, Alper Yegin wrote:
>Hi Sam,
>
>Continuing the discussion we had during the EAP WG…..
>
>Various mobile and wireless architectures place the authenticator (NAS) on 
>a centralized node instead of on each access node (e.g., IEEE 802.11 
>that manages the network access sessions of each mobile terminal. Various 
>services such as mobility management (L2 and L3), network access, radio 
>resources are controlled in that element.
>
>Technically the NAS can be placed on the AP/BS, but given the high number 
>of these elements, and the need to coordinate sessions as mobile stations 
>move from one to other, a hierarchical model where all such management 
>functionalities are aggregated in a centralized server is preferred.
>
>I hope this clarifies the motivation behind the separation of NAS from the 
>access nodes.
>
>Regards,
>
>Alper
>