Network Selection

1
Network Selection

• IETF-59
• Jari Arkko

2
Outline

• Problem Definition
• IEEE and 3GPP Responses
• Solution Space
• 3GPP network selection (Farid)
• Draft-Adrangi (Farid)
• Next Steps

3
Problem DefinitionDraft-ietf-eap-netsel-problem-0
0.txt

• Jari Arkko
• Bernard Aboba

4
We need network selection.
but what is it?
5
Theres actually multiple problems

• Access Network Discovery
• Which access point to attach to?
• Identifier Selection
• Which identity and credentials to use in this AP?
• Selection of roaming intermediaries
• How to route the AAA conversation to the home
  network?
• Payload Routing
• How to route payload traffic in the right way
• Filters and mandatory tunnels

6
An alternative decomposition

• Discovery
• Access networks and access points
• Home networks available through these
• Mediating networks
• Decision
• Manual or automatic
• Automatic is preferred
• Most likely needs some pre-provisioned preference
  information
• Indicating the selected network
• Attach to the chosen network and access point
• Provide the chosen identity and home domain
• Possibly provide some hints about mediating
  networks

7
Recommendations

• All four problems are relevant.
• Potential need for new solutions, at least for
  the three first problems.
• The problems are very hard if you consider them
  with large number of networks, fast handoffs,
  security, and automatic decisions.
• The proliferation of multiple network selection
  technologies within IEEE 802, IETF, and 3GPP
  would be bad.
• Solving all problems with current link layers and
  existing network access devices may not be
  possible. Phasing?

8
Responses from 3GPP and IEEE

• Jari Arkko

9
Feedback from 3GPP SA2 WLAN group

• Are the contents of the draft technically
  correct?
• A complete answer to this question takes
  involvement of more groups than SA2 (e.g. CN1 and
  CN4 who are responsible for protocol details).
• Are all aspects of the problem covered?
• After a quick look, the relevant parts from SA2
  seem to be covered.
• What part of the problem 3GPP wants to solve?
• Problem 1 (Access Network Discovery) and 3 (AAA
  routing) are relevant to 3GPP.
• Problem 4 (Payload Routing) is considered a
  separate problem within SA2 scope and is still
  under discussion.
• Problem 2 (Identifier Selection) is considered at
  this stage out of scope.

10
IETF/IEEE 802.11 Meeting - Summary

• ...
• EAP Network Discovery
• Q Is This being Addressed in 802.11?
• A Network Discovery alternatives are in scope
  for proposed Wireless Interworking SG
• ...

11
Observations

• 3GPP uses existing L2 mechanisms for problem 1,
  expects an IETF solution for problem 3
• Needed for 3GPP Release 6
• Is IEEE interested in more than problem 1?
• Decision whether this is in scope in 6 months
• Other IEEE groups than 802.11 are also working on
  this area, for instance 802.21 is planning to
  provide a long-term solution for different link
  layers (1..3 years)

12
Solution Space

• Jari Arkko

13
Proposed Priorities and Possible SDOs

• There is current interest in problem 1 (access
  network selection)
• There is current interest in problem 3 (roaming
  intermediary selection)
• Ignore the rest for now...
• Problem 1 belongs to layer 2
• Problem 3 needs at least partial IETF work,
  though intermediary discovery could also be done
  at layer 2
• Long-term, discovery is most efficient at layer 2
• gt Any IETF intermediary discovery solution would
  necessarily be short-term

14
Accommodating Multiple Discovery Mechanisms

• It makes sense to separate discovery from
  selection
• It is likely that both configured databases and
  dynamic discovery is employed must be able to
  switch to another source
• Example
• Using the bang syntax from RFC 2486 to route via
  an intermediary
• Using a phone book, L2 discovery, or EAP
  discovery to find the intermediaries
• Draft-arkko-roamops-rfc2486bis-00.txt adds, among
  other things, some rules restrictions on the
  use of the bang syntax

15
Next Steps

• Jari Arkko

16
Next Steps

• Need to ask IEEE 802 whether the discovery part
  of problem 3 is being considered, and when
  results would be available
• Need to send the problem definition as input for
  the groups working on the long-term L2 solutions
• Need to decide how to accommodate for the
  selection of roaming intermediaries bang syntax?
• NAIbis next steps being discussed with ADs
• Not in EAP WG
• Need to decide how roaming discovery is performed
• Wait for the final L2 solution ( multiple years)
• Short-term solution now until L2 solution arrives
• EAP WG is one potential place for the short-term
  solution

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What Does the WG Want to Do for Roaming Discovery?

• 1) Send the problem to L2?
• 2) Adopt something like Farids draft?
• To be published later as an Informational RFC
• Perceived as a short term solution (some years)
• 3) Vendor-specific IdReq contents or methods
• Also short term
• 4) Nothing
• Requirement input we have gotten speaks against
  this

18
Some tradeoffs

• Send the problem to L2
• May take longer than other alternatives
• Passing information between EAP and L2
• Needs at least a firmware upgrade
• Probably the most efficient scheme in the long
  run
• Adopt something like Farids Draft
• No access point upgrades if done from RADIUS
  proxy
• Fast to specify
• Not very clean way to do it, but the only
  short-term solution?
• Vendor-specific
• Might get many, even from SDOs (PP, PP2, )
• Lack of review, IETF doesnt get to put in
  restrictions etc.