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Proposing 802.1x for broadband access / Ethernet access

I don't know whether it is suitable to discuss this topic here. What I strongly suggested is that some BRAS product, like 6400, 7400, BBSM, should better implement the 802.1x function, based on some of my network deployment consideration. 802.1x is not only part of WLAN access.

Today most of the broadband access is "Ethernet to the first meter", which means that the end user interface is mainly Ethernet. As for the middle network, which lies between user terminal and service provisioning point(typically a BRAS/NAS) of SP's HeadendPoP, does act like LAN bridges, through some emulation or encapsulation(like 1483), or natively(optical, structured wiring).

PPPoE is now widely used for AAA in broadband access. Overall, it is ineffcient, costly, complex, and then, easy to cause problem. Serious performance problem arose when lots of 1500-bytes packets coming down from Internet, caused by fragment, and simple IPoE data plane solution is needed.

But despite all the constrains, PPPoE is convenient for accounting, service provisioning/mapping, and easy to integrate with existing AAA infrastructure of dial-up access. RBE and RFC 3046 has addressed some problems on subscriber management solutions based on IPoE and DHCP, it can't replace PPPoE ultimately yet, whose AAA is based on user NAI, not only the physical circuit/port, and service is also mapped based on user NAI.

Then I think EAPOL is a better choice, than just piggybacking complex authentication transactions on DHCP messages as DHC-WG is doing. 802.1x has the same subscriber management AAA capability as PPP, and can be used together with DHCP. The session management is explicit just like PPP, easy to integrate with radius; and it is in a seperate outband signal plane, not like PPP, with the data plane forwarding is IPoE directly.

802.1x authenticator PAE should be implemented in the first "circuit aggregation unit" for security and management. For ADSL, which is 6400/7400; for Cable, which is uBR7200. In these cases, BRAS co-locate with the authenticator PAE.

For LRE or native LAN, PAE is the first low-end access LAN switch(29xx LRE, 1924...) or wirelss AP, and a additional upstream BRAS(maybe BBSM or catalyst 6500) should exist. radius proxy should be implemented in this position, to intercept the AAA transactions between downstream PAE and radius server, for convenient to apply service policy (ACL,QoS,) based on user profiles from AAA result. In these cases, PAE is far "down" from BRAS, then PVLAN may need to be configured in each middle switch, preventing any two downlink ports from communicating, to assure any end nodes must communicate with each other through the BRAS, creating a virtual circuit from user node to BRAS in SP's HeadendPoP, just like PPPoE.

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