CURRENT_MEETING_REPORT_ Reported by Claudio Topolcic/ BBN The CO-IP Working Group met at the May 1-4 IETF Meeting at Carnegie-Mellon University. During the Tuesday sessions we tried to pick up where we had left off in Florida State. We heard updates on DARTNet and the TWBNet. Tony Mazraani gave a progress report on the COIP kernel and a presentation on Washington University's work on Resource Management in Broadcast Lans. Work toward defining experiments for the DARTNet was hindered since not all the key people were present. We spent the balance of the sessions discussing the current draft of the ST-2 protocol specification. Charlie Lynn had previously edited and distributed the current draft of the ST-2 protocol specification. He had also written up a number of issues that needed more thinking. The group discussed these issues and a few others that came up during the meetings. A number of editorial comments to the draft were discussed. These included some minor restructuring to minimize repetition and increase clarity. More forward and backward pointers were suggested, as well as more examples. Numerous editing changes were suggested. We discussed the relation between ST and IP. We decided to allow two forms of the ST header. The short form is as had previously been specified. A long form is structured like an IP header so that it can be processed by IP-only agents, and takes the place of the concept of IP encapsulation. The long form may also be used when IP security is required or to reduce either deliberate or accidental denial of service problems. The issue of use of multicast lead to a lot of discussion. Ideally, we would like to be able for an ST agent to request that the local network dynamically create a multicast group for use by a stream, as its use could reduce the network bandwidth required to support the stream. Unfortunately, there does not seem to be much support for dynamic management of multicast addresses (how does a ``user'' dynamically request a multicast address at a given protocol layer, what agent(s) on a network robustly assign multicast addresses, how are the assigned addresses mapped into addresses for use above the network layer, e.g., IP multicast addresses, how are the assigned addresses reliably released/garbage collected, etc.). It was felt that trying to create such a service was a challenging problem tangential to the work of the Working Group and should be delegated to some other group. The result was to either to use replication instead of multicast, or to use static multicast groups. The problem with the former is wasted bandwidth, that with the latter is scaling -- what were formerly seperable problems (solvable by each stream independantly) now become problems which must be solved in common by all streams on a network. HID negotiation is one example. 1 We discussed mechanisms by which changes could be made to established streams. For example, it may be desirable to allow a request to change a stream's bandwidth to allow a range of possible bandwidths. Also, when a new target is added to a stream, it would be desirable to decrease the stream's bandwidth, if that is allowed by the stream, if the new target can only be added with that decreased bandwidth. These features causes some difficulties in coordinating the changes among the ST agents, as well as the applications, while maintaining the uninterrupted flow of data packets. Other specific issues discussed included the following: 1. A Target cannot be an IP multicast group. 2. The ACCEPT message should be delayed until the HID negotiation has been completed. 3. We are not addressing the issues of spoofing (beyond the security features to be provided for IP by SDNS), intentional denial of service, or unintentional denial of service resulting from broken routes. 4. The structure of the ``Group of Streams'' specification. 5. Whether source routes would be strict, loose, strict in ST and loose in IP, or something else. This issue was not resolved. ATTENDEES Fred Bohle fab@saturn.acc.com Terry Braun tob@kinetics.com Stephen Casner casner@isi.edu Danny Cohen cohen@isi.edu Richard Fox sytek!rfox@sun.com Jonathan Goldick goldick@b.psc.edv Jack Hahn hahn@umd5.umd.edu Charles Lynn clynn@bbn.com Tony Mazraani tonym@flora.wustl.edu Zaw-Sing Su zsu@sri.com Ian Thomas ian@chipcom.com Claudio Topolcic topolcic@bbn.com Dave Wood wood@gateway.mitre.org 2