IPv6 over xDSL: The DIODOS Proposal

1. IPv6 over xDSL: TheDIODOS Proposal Athanassios Liakopoulos aliako@grnet.gr Greek Research & Technology Network International IPv6 Workshop, Kopaonik, March 6th,2005

2. Outline • Introduction to DSL technology • IPv6 services over DSL • The DIODOS project • IPv6 services in DIODOS International IPv6 Workshop - Kopaonik, March '05

3. Entities involved in an xDSL environment • Subscriber (xDSL User) • Network Access Provider (NAP) • Responsible for the management of the copper local loop. • Network Service Provider • Responsible for providing interconnection with the Internet. • May offer other added-value services. International IPv6 Workshop - Kopaonik, March '05

4. Basic Network Elements • Subscriber (DSL User) • PC, modem, CPE router • Network Access Provider (NAP) • DSLAM, BBRAS, radius server (?) • Network Service Provider • Edge router, radius server (?) International IPv6 Workshop - Kopaonik, March '05

5. Implementation details • xDSL modem • Encapsulates Subscribers’ traffic to ATM cells, signal (de)modulation • DSL Access Multiplexer (DSLAM) • Signal (de)modulation, aggregates traffic over ATM links • Broad Band Remote Access Concentrator BBRAS • Terminates the Subscribers’ ATM connections, forwards traffic tothe NSP edge router. • Radius Server • Contains configuration templates • NSP edge router International IPv6 Workshop - Kopaonik, March '05

6. Ethernet bridging over ATM • The CPE forwards IP packets using multi-protocol encapsulation over ATM adaptation layer 5 (AAL5). • Minimum functionality is required for CPE, aka xDSL modem (L3 unaware device). • A single ATM PVC is used for IPv4/6 interconnection • Subscriber’s PCs are configured with static IPv6 address, or via DHCPv6 or via auto-configuration • This method does not support authentication and authorization functionality! International IPv6 Workshop - Kopaonik, March '05

7. PPP over AAL5 (PPPoA) • The CPE supports IPv6/4 packet forwarding and interconnects multiple systems in the Subscriber’s local network. • A single PPPoA session is established over a ATM PVC allowing the CPE router to establish two PPP sessions; an IPv6 (IPCPv6) and an IPv4 (IPv4) • IPv6 addresses are assigned automatically over the PPP sessions using attributes stored in a centralised radius server or a local database. • The CPE can be authenticated using one of the multiple protocols, such as PAP, CHAP, MS-CHAP, EAP, etc. International IPv6 Workshop - Kopaonik, March '05

8. PPP over AAL5 (PPPoA) • In case the NAP and the NSP are different, the PPP sessions do not terminate at the BBRAS but at the edge router. • BBRAS = L2TP Access Concentrator (LAC) • Edge router = L2TP Network Server (LNS) • Two PPP sessions are established from the CPE router, which terminate at the LNS. • Address assignment and authentications methods are performed in the same was as previously but now the radius server is managed by the NSP. International IPv6 Workshop - Kopaonik, March '05

9. PPP over Ethernet (PPPoE) • Separate PPP sessions are established between the CPE and the BBRAS for IPv6 and IPv4 traffic. • Sessions terminate in the LNS in the NSP network (not shown). • PPP sessions may terminate in the Subscriber’s system. This allows the CPE to be L3 unaware and, thus, cheap(!) but requires specific software to be installed in the Subscribers’ systems. International IPv6 Workshop - Kopaonik, March '05

10. The DIODOS project • In Greek, the word “diodos” means “passage”. • Established under the authority of the Ministry of Development, the Ministry of National Education & Religious Affairs and the Ministry of Transport and Communications • Realised by the General Secretariat for Research and Technology with the support of Greek Research & Technology Network. • http://www.diodos.net.gr/ (in greek) International IPv6 Workshop - Kopaonik, March '05

11. DIODOS objectives (?) • Improve the quality of training in Greece • Enabling tele-teaching, collaboration, videoconferencing, etc • Easy access to available content, such as digital libraries, multimedia content, virtual labs, etc. • Increase the penetration of broadband technology in Greece • Give motives to ISPs to improve their infrastructure • Create future potential Users International IPv6 Workshop - Kopaonik, March '05

12. DIODOS Entities • Network Access Provider (NAP) • Network Service Provider • GRNET • Provide the Internet interconnection services • Accounting – Management • ISPs • Maintaining the radius servers • Accounting and billing of Subscribers International IPv6 Workshop - Kopaonik, March '05

13. Obstacles • Greece-wide service • Centralised architecture, high availability • Limited amount of time for implementation and deployment • Management complexity • Three different entities involved • Information System had to be implemented • Lack of management tools • Open to all competitive ISPs International IPv6 Workshop - Kopaonik, March '05

14. Why IPv6 support is important? • “Always-on” xDSL connections require a routable IP address per subscriber • Thousands of new IPv4 addresses have to be allocated for DIODOS connections. • In the hypothetical case that all the students on Aristotle University of Thessaloniki take advantage of DIODOS programme, more than 150 class C networks has to be allocated! • A /9 IPv4 address has to be allocated to all Greek Universities! International IPv6 Workshop - Kopaonik, March '05

15. Why IPv6 support is important? (2) • Take advantage of the experience gained from other IPv6 deployments in Greece. • GRNET provides IPv6 interconnection services since the end of 2003. • The Greek School Network (GSN) introduced IPv6 interconnection services over xDSL on a pilot basis. If DIODOS will support only IPv4 services, it may affect the impact of the other IPv6-enalbed networks. International IPv6 Workshop - Kopaonik, March '05

16. Why IPv6 support is important? (3) • Exposing students to new technologies is one of the major objectives of any educational system. • New advanced services and applications may take advantage of the unique IPv6 features, • Large portion of Greek student still has not access to IPv6 technology DIODOS could become a “vehicle” to improve the educational process and further stimulate innovation. International IPv6 Workshop - Kopaonik, March '05

17. Possible IPv6-enabled implementations • Use Global Unicast IPv6 and Private IPv4 addresses • Overcome the IPv4 depletion problem • Static NAT is used for IPv4 connectivity • Possible scalability problems. • Problems with application protocols caring IP addresses in their payload • Application-Level Gateways (ALG) are needed • Affected protocols: ICMP, FTP, H.323, SNMP, DNS, NetBIOS over TCP/IP (NBT) etc. • Difficulties with IPSec. International IPv6 Workshop - Kopaonik, March '05

18. Possible IPv6-enabled implementations • Use open replay 6to4 servers • No solution to IPv4 depletion problem • Security configuration • Tunnel Broker • More complex solution than 6to4 tunneling • No solution to IPv4 depletion problem • Open VPN solutions International IPv6 Workshop - Kopaonik, March '05

19. Thank you! International IPv6 Workshop - Kopaonik, March '05