PANA in DSL networks draft-morand-pana-panaoverdsl-01.txt

1
PANA in DSL networksdraft-morand-pana-panaoverds
l-01.txt

• Lionel Morand France Telecom
• Alper Yegin Samsung
• Yoshihiro Ohba Toshiba
• John Kaippallimalil Huawei

IETF-71, Philadelphia
2
Draft History

• IETF 66
• PANA use case for DSL removed from PANA Framework
• IETF 67
• First presentation of the "PANA over DSL" draft
  (v00)
• IETF 67 and IETF 71
• Draft frozen during finalization of PANA protocol
• DSL Liaison on access authentication requirements
• IETF 71
• Update version of the "PANA over DSL" draft (v01)
• Based on final version of the PANA base protocol
  and comments received and outputs of DSLF liaison
  discussions

3
Context

• Evolution of DSL architecture in two steps
• Moving from ATM-based aggregation to Gigabit
  Ethernet
• Moving from PPP-based environment to IP-based
  model
• "IP Sessions" model ongoing work in DSL Forum
• Basically, an IP session represents the
  subscriber IP traffic associated with an IP
  address
• Need for a subscriber access authentication
  mechanism
• DSL Forum working around DHCP evolution for
  supporting EAP
• DSL Liaison discussion during IETF70 in the
  Internet Area meeting session
• PANA should also be considered a natural
  candidate
• Fulfill DSL Forum security requirements provided
  in the Liaison

4
Summary

• Provides guidelines for PANA deployment over DSL
  access networks
• Focus on DSL networks migrating from
• a traditional PPP access model
• Where PPP is used to carry authentication
  parameters (PAP/CHAP or EAP methods)
• to a pure IP-based access environment
• No built-in explicit per-subscriber access
  authentication
• Use of DHCP option 82 for implicit line-based
  authentication
• PANA provides such a mechanism in this environment

5
From v00 to v01

• Alignment with PANA final specification
• Clarification on the possible PAA-EP interface
• Removal of reference to SNMP or ANCP
• Description of DHCP snooping/triggering mechanism
• Reorganization of the draft
• New section on the use of the MAC address as
  authorized device ID
• Added section on specific implementation example
• With the use of Link-local IPv4 address
• More details in message flow descriptions

6
PAA/EP Location
PAA/EP
ISP
DSL Modem/RG
DSLAM
API or DHCP Snooping
PAA
EP
ISP
DSL Modem/RG
DSLAM
7
PaC Location
PaC
PAA/EP
ISP
DSL Modem/RG
DSLAM
PaC
Bridge
1/ Bridged Mode in IPv4/IPv6
PAA/EP
PaC
ISP
DSL Modem/RG
DSLAM
NAT/Router
2a/ Routed Mode in IPv4
PaC
PAA/EP
PaC
ISP
DSL Modem/RG
DSLAM
PaC
Router
2b/ Routed Mode in IPv6
8
Use of PRPA/POPA

• Mainly useful in IPv4 context
• to prevent waste of scarce IP resources
• In IPv4 context, PRPA may be
• Link-local IP address
• Private IP address
• Temporary allocated IP address
• with short-lease and/or limited use
• After a successful authentication, POPA is
  configured using DHCP

9
Generic Message Flows
DSL Model/RG or host (PaC)
DSLAM (EP)
BRAS (PAA)
AAA Server
1. PRPA Configuration
2. PAA Discovery
3. PANA Authentication
RADIUS/Diameter Authentication
4. POPA Configuration
5. EP filter setup
6. IP Session/data traffic
Only needed if the IP address needs to be
reallocated
10
Specific example

• Deployment scenario in which
• DSL Network configuration with
• PaC in the DSL modem/RG
• BRAS hosting PAA, DHCP Server/Relay, and AAA
  client
• DSLAM acting as EP
• Link-local IPv4 address as PRPA
• DHCP-based PAA discovery
• EAP-MD5 Authentication method
• POPA configured using DHCPv4
• EP is triggered by DHCPACK whose 'yiaddr' field
  is filled

11
Specific Message flows
DSL Model/RG or host (PaC)
DSLAM (EP)
BRAS (PAA)
EP Filter allowing only DHCP and PANA
AAA Server
No IP Address Allocation
1. Link local PRPA Configuration
2. DHCP Inform (req PAA option)
3. DHCP Ack (PAA option)
4. PANA client initiation
Authentication
5. PANA Auth Req (EAP-MD5 Challenge)
6. PANA Auth Ans (EAP-MD5 resp)
7. RADIUS Access Req (EAP)
8. RADIUS Access Accept (EAP)
9. PANA Auth Req (EAP Success)
10. PANA Auth Ans (Ack)
11. DHCP Discover
12. DHCP Offer
IP Address Allocation
13. DHCP Request (with IP address in 'yiaddr')
14. DHCP Ack
15. IP Session/data traffic
EP Filter update based on DHCP snooping
12
Next Step

• Provide more details on
• The use of link-local IP_at_
• Mechanism to avoid/resolve possible address
  conflict/collision
• PANA impacts on DSL network
• Host, DSL Modem, DSLAM, BRAS, DHCP server
• DSLAM acting as EP
• And the use of DHCP as EP triggering mechanism
• IP_at_/Identity binding management
• Tight/loose coupling between DHCP/PANA/AAA
• Investigate/clarify the case of hosts behind a
  NAT/Router in IPv4
• Does PANA support NAT traversal?
• Consider Unspecified IP address?
• As an alternative to link-local IP address as PRPA

13
Thank You