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6   Implementation of IPv6 in the CESNET2 network

In 2003 we saw a relatively massive penetration of the IPv6 protocol into the research and education networks. The pan-European GÉANT network started a production IPv6 service in the dual-stack mode and most connected NRENs have also activated IPv6 on their access links to GÉANT.

As far as the CESNET2 backbone is concerned, we implemented a new technology instead of the previously used tunnelling, namely IPv6 transport over MPLS (Multiprotocol Label Switching).

In the new setup, IPv6 is in a position that is theoretically almost equivalent to IPv4. I reality, though, the situation is considerably worse since

• IPv6 support in routers and other devices is still weak compared to IPv4 in terms of performance, features and stability,
• global IPv6 routing is far from being optimal, especially due to a huge number of tunnels that distort the view of the global topology that is used for BGP routing decisions,
• attractive servers and services, which definitely represent the most important aspect for end users, still rather rarely support IPv6.

In order reach the critical mass of users and through it the ultimate worldwide expansion, IPv6 surely needs a certain degree of a "political" support, primarily from the side of institutions that finance research and development projects. Recently, however, we have been witnessing an unfortunate shift where IPv6 is no more a pragmatic solution to the objective problems of the Internet but rather as a totem or trump card in the technological competition (especially) between Europe and North America. This trend is behind the attempts to accelerate the deployment of IPv6 in end-user networks or even notions like "migration" to IPv6. However, such an approach may potentially lead to adverse effects. Users accustomed to the comfort of IPv4 cannot be expected to take into account "higher interests" and will reject IPv6, unless it provides a comparable quality.

In our view, the best strategy of IPv6 development is its gradual and (as much as possible) non-invasive deployment, starting from backbone networks through campus and local networks down to the end users. In the ideal case the distinction between IPv4 and IPv6 will be completely blurred and either of the two protocols will be used as needed without any intervention or perhaps even knowledge on the side of the user. Therefore, CESNET recognises its role namely in

• an improved support for IPv6 in the backbone network,
• gradual deployment of production IPv6 in the nodes,
• providing the services and applications on top of IPv6 (along with IPv4),
• dissemination of know-how to both users and network administrators.

6.1   Building the IPv6 backbone network

In 2003 we realised the transition from tunnelling IPv6 in IPv4 to the MPLS technology that is used for IPv4 transport as well. It means that IPv6 is now handled almost identically as IPv4. This fact resulted in an improved stability of the IPv6 backbone. As 6PE routers we currently use the Cisco 7500 routers that are still available in most backbone PoPs. So far we were not able to install IPv6 directly on the Cisco 7600 routers that serve as PE devices for IPv4. The reason was a seriously delayed delivery of crucial hardware and software components (in particular the Supervisor 720 engine). Previously used PC/Unix routers are not suitable for this backbone architecture since they lack support for MPLS.

In the course of 2003 IPv6 has been enabled in all gigabit nodes of the CESNET2 network: Praha, Ústí nad Labem, Hradec Králové, Pardubice, Ostrava, Zlín, Olomouc, Brno, Plzeň and České Budějovice. Two smaller nodes (Karviná and Opava) have also been connected to the IPv6 backbone. The configuration of the entire backbone (including international lines) is shown in Figure.

For IPv6 routing we use the internal BGP protocol configured with two route reflectors. The choice of iBGP was essentially mandated by MPLS. For testing purposes we also use OSPFv3 among the nodes Ostrava, Karviná and Opava. The consolidation of the router platform enabled us to phase out the RIPng routing protocol that was still in use in 2002.

The connectivity and basic services of IPv6 are being monitored using the standard monitoring system saint.cesnet.cz. We use either the modules available for the Nagios program, or modules developed by ourselves. The monitoring system has a L2 connection to the IPv6 network. We monitor the following areas:

• reachability of backbone routers,
• reachability of border routers of our peering neighbours,
• status of the important IPv6 services,
• BGP routing data.

The migration to MPLS has had an unpleasant consequence for network statistics: we are not able to distinguish IPv6 from IPv4 any more. For this reason we have temporarily suppressed the specific measurements of IPv6 traffic volumes on backbone links and thus have only aggregate volumes for both protocols.

6.2   IPv6 in the networks of CESNET member institutions

Table gives an overview of institutions that have IPv6 deployed in at least one network. It is subdivided according to the individual backbone nodes and also the type of connection.

The PASNET network in Prague has so far no support for IPv6 and so the schools and institutes of the Czech Academy of Sciences outside of the Dejvice campus can connect only via tunnels. Nevertheless, CESNET NIC has already included PASNET in the addressing scheme and the address allocations follow common scheme so that after migrating to a native connection all addresses should remain valid.

The addressing scheme is still the same as described in the technical report 3/2001. The fact that our original prefix 2001:718::/35 was shortened to /32 has not been projected into the allocation policy yet and we leave the extra address space open for future purposes.

6.3   IPv6 peering in the Czech Republic

Other autonomous systems in the Czech Republic can peer with the CESNET2 network only through the national exchange point NIX.CZ. On the CESNET side, the border router towards NIX.CZ is R1.

By the end of 2003 CESNET has the peering agreements with the following subjects:

• GTS CZECH (AS 2819)
• Tiscali (AS 3257)
• IPEX/GIN (AS 9080)
• Pragonet (AS 12767)
• Casablanca (AS 15685)

Peering with the XS26 network (AS 25336) is currently implemented using an IPv6-over-IPV4 tunnel terminated at the R62 router.

6.4   Foreign connectivity

In 2003 we realised native IPv6 interconnections with the pan-European research network GÉANT and with the experimental network of the 6NET project. The same access line to GÉANT in now used for both IPv4 and IPv6 protocols. The router on the CESNET side (R21, Cisco GSR 12008) operates in the dual-stack mode. In contrast, the 6NET access link carries only IPv6 since the 6NET network is IPv6-only.

Transit IPv6 connectivity is provided to CESNET by Telia International Carrier (AS 1299).

National and international external IPv6 connectivity is summarised in Figure.

6.5   Project presentations and publications

6.5.1   Seminars

An important event aimed both at a general IPv6 technology dissemination and presentation of our results in this area was the seminar IPv6 - development and implementation on October 22nd, 2003. We presented four lectures:

• Recent status of IPv6 standards by Pavel Satrapa
• Current worldwide IPv6 infrastructure by Ladislav Lhotka
• Experiences with IPv6 service in the CESNET2 network by Martin Pustka
• Liberouter project by Jiří Novotný

The seminar was received very positively and the page with the presentations and video recordings of the lectures, accessible from www.cesnet.cz, has already had many visitors.

Apart from this event we have been regularly reporting about our work at the meetings of EU projects TF-NGN and 6NET and recently we also took part in the preparation of new projects for the 6th Framework Programme of the EU.

6.5.2   Web

We have been continually updating the WWW pages of the IPv6 project on www.cesnet.cz, which contains diverse information about the current topology and status of our network, addressing and so on.

Another server administered by the project group is www.ipv6.cz that is intended as a source of general information about IPv6. Apart from texts describing various aspect of the IPv6 technology and implementations, this portal offers a number of IPv6-related mailing lists. There have been no substantial changes in 2003, only the existing contents were updated.

Finally, the www.liberouter.org server is devoted to the presentation of the Liberouter project. The contents are entirely in English, as this project also has foreign participants. During 2003 the server was renamed (from the original name www.openrouter.org), its structure and design was significantly improved and a lot of new information added.

6.5.3   Other publications

In 2003 we also published six contributions in the on-line magazine Lupa dealing with diverse IPv6-related topics like deployment, evolution of standards and technological trends.

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