pana in dsl networks draft-morand-pana-panaoverdsl-01.txt

IETF-71, Philadelphia

PANA in DSL networksdraft-morand-pana-panaoverdsl-01.txt

Lionel Morand France TelecomAlper Yegin Samsung

Yoshihiro Ohba ToshibaJohn Kaippallimalil Huawei



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


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


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


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


PAA/EP Location

LaptopDSL Modem/RG DSLAM

BRAS

ISP

PAA/EP


BRAS

ISP

PAAEP

API or DHCP Snooping


PaC LocationLaptop

DSL Modem/RG DSLAM

BRAS

ISP

PAA/EPPaC

PaC


BRAS

ISP

PAA/EP

PaC


BRAS

ISP

PAA/EPPaC

PaC

PaC

Bridge

NAT/Router

Router

1/ Bridged Mode in IPv4/IPv6

2a/ Routed Mode in IPv4

2b/ Routed Mode in IPv6


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


Generic Message FlowsDSL 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


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


Specific Message flowsDSL Model/RG

or host(PaC)

DSLAM (EP)

BRAS(PAA)

AAA Server

1. Link local PRPA Configuration

15. IP Session/data traffic

2. DHCP Inform *(req PAA option)

3. DHCP Ack (PAA option)

4. PANA client initiation

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 Discover12. DHCP Offer

13. DHCP Request (with IP address in 'yiaddr')

14. DHCP Ack

No IP Address

Allocation

EP Filter allowing

only DHCP and PANA

IP Address Allocation

EP Filter update based on DHCP

snooping

Authenticatio

n


Next Step• Provide more details on:

– The use of link-local IP@• 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@/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


Thank You

pana in dsl networks draft-morand-pana-panaoverdsl-01.txt

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