47th IETF
Monday, March 27, 2000
Network Access Server Requirements, nasreq (Next Generation) WG
Recorded by: Herbert Lin, hlin@nortelnetworks.com
Chaired by: David Mitton, dmitton@nortelnetworks.com
Agenda:
1. Agenda Bashing
2. Relationship of nasreq documents to AAA WG's
3. Document Status
- NAS Operational Model
- NAS Extended Radius Practice
- Criteria for Evaluating NAS Protocols
- Evaluation of Protocols against NAS Criteria
4. Final Comments on Above
5. Megaco; NAS Package Input?
6. Next Steps
----
1. There were no agenda issues.
2. AAA vs. Nasreq documents
The AAA Network Access Requirements draft now includes Nasreq
documents by reference. The most recent changes to the Criteria
draft was made to harmonize requirement terminology and description
between the two documents, as discussed in the AAA WG Interim
meeting. We need to make sure we stay in sync.
3. Document Status and Mailing List
3.a. Drafts Status:
- NAS Operational Model
draft-ietf-nasreq-nasmodel-01.txt WG Last Call
- NAS Extended Radius Practice
draft-ietf-nasreq-ext-radiuspract-02.txt WG Last Call
- Criteria for Evaluating NAS Protocols
draft-ietf-nasreq-criteria-04.txt WG Last Call
- Evaluation of Protocols against NAS Criteria
incomplete
4. Comments:
4.a. Extended Radius Draft Comments
There were some comments that there were still mentions of vendors and
products in this document, even after the recent edits. These have
been reduced to a simple list at the end of the document. After
some discussion, the group as a whole didn't seem to have a problem
with this.
4.b. The three above documents will be put up for a formal final WG Last Call
and with no substantive comments will be advanced to the IESG for any last
review and RFC considerations.
4.c. Evaluation of Protocols draft or lack thereof
This working group is chartered to product a protocol evaluation draft based
on our NAS Criteria. We have had several presentations at prior meetings, but
no document has been published yet. Should we follow through on this, or
revector our energy into the AAA WG?
Discussion:
What is the purpose of this document: "Evaluating NAS Protocols"?
- IESG: It is not just conflict with AAA; but we also to fill all
the requirements as a whole.
- AAA WG took Nasreq requirement document as reference for
evaluation
- Nasreq document has a lot of more details than AAA requirement
documents
- We need someone familiar with the topic and just produce the
documents for comments
- Do we need to just go ahead and produce this document and
coordinate with AAA group?
- We could either choose to include this effort by reference
(e.g. make the AAA document refer to us, or directly include our text in the
AAA document by participation)
- It was observed that many of the same people would be involved
in either effort, and this may be a redundant.
- There were no volunteers. However various people in the room did
not want to give up.
- A Hum was called and consensus was that we should coordinate with
AAA WG.
5. Megaco (Media Gateway Protocol)
A typical relationship of Media Gateway Controller and NAS is shown below.
SS7--> +----------+
-----------| MGC |
+----------+
^ |
| |
| | Megaco/H.248
v |
+----------+ AAA +-------+
TDM call-->| | ---> | AAA |
-----------|D-channel | +-------+
| NAS | IP Data
| |<----------------->
+----------+
>From signaling point of view, NAS is responsible to setup TDM calls coming
to the D-channel. Do we need to create a new protocol for AAA to
communicate with NAS to set up the calls for VoIP applications and L2TP
Tunneling applications?
NAS and AAA relationship:
- Concerns are: what are the interfaces between MGC and AAA?
- Concerns are: what are the timing issues?
- Concerns are: Are we going to allow thousands of real-time calls'
authorizations flow thru AAA?
- Concerns with picking up the complexity and expericence of NAS services
and AAA in another protocol!
- AAA group is meeting later in this IETF meeting to discuss these Megaco
call set-up issues.
- Call-back profile in AAA:
ss7 call setup ---> MGC --->AAA
|
call-back authorization <----|
- Megaco WG is only looking at L2TP for NAS application today.
- Other issues are policy issues on MGC:
- How do you set up the relationship between MGC and AAA?
a proposal below:
+-----+
| | Call request +----------+
| |----------------->| AAA |
SS7 calls --->| MGC |<---Set up L2TP---| |
| | +----------+
+-----+ ^
^ |
| Megaco w/AAA data |
v |
+-----+ |
| | AAA |
| |----------------------+
PRI calls --->| NAS |
| | IP Data
| |<------------------>
+-----+
- MGC does call control/setup/policy management
- Some NAS devices are very simple and may not support AAA
function, in the future (given this kind of deployment).
- Megaco is meeting on Thursday morning to discuss these issues.
6. Next Steps?
Per discussion and hum consensus, we are NOT going to produce a Nasreq
Protocol Evaluations draft; but the door is always open.
Given no more active documents, the chair does not expect to call for more
meetings unless some particular need arises. The group will stay active on
the mailing list while the AAA effort is ongoing.
<attached presentations from Nov 1999 meeting>