XMSF Network Group Status

1. XMSF Network Group Status • Working assumptions: • The simulation will not be confined to individual networks • either private networks individual ISPs • Application should not be media-aware • Must be able to run over the public Internet • without this, can’t achieve the benefits of XMSF to commercial industry • so defense can’t enjoy them either! • Scalability and resilience are essential in XMSF

2. Precondition for Success • Leaders and workers from the three major technical areas (Web, Internet, M&S) must work as a coordinated team • with effective (human) interfaces among all elements • we have learned that it does not work to “throw it over the wall” ! • solutions need to work end-to-end

3. Network QoS: meets a specified or negotiated standard for: • capacity, latency, jitter, loss in a statistical sense • can be done today in general terms within individual ISP networks • also Internet-wide by proactive path selection • a workable approach to defining consistency needs of applications * • e.g. does the application need to know order of sending • this requires translation from application requirements to network capabilities • must define acceptable tradeoff between reliability and latency in a parameterized form * • if a negotiated solution, mechanism(s) for negotiation needed • could be different for global and local negotiation • we don’t know how to do Internet-wide QoS negotiation * early work project

4. M&S needs to be able to characterize network requirements • and the impact if the requirements are not met • this implies they must be measured and understood * • cannot assume any-to-any communication • firewalls and network address translation (NAT) get in the way • application or middleware should be able to adapt to take advantage of changing network capacity* • implies higher layer must be aware of available capacity • must define security requirements: • authentication • denial of service protection • confidentiality • auditing • integrity

5. Many-to-many multicast • trend is away from providing this as a network layer capability • no good business model • one-to-many may become available • must define requirements for reliability* • e.g. selectively reliable/real-time, fully reliable/non-real-time • it is impossible to have fully reliable/real-time multicast • identifying and responding to congestion is a requirement • it will be necessary to support M&S needs for networked group communication over non-multicast network layer*

6. In general the simulation network could be an overlay network* • for example, virtual private network (VPN) • allows an ISP or the Internet to meet specialized requirements of M&S • Need a capability for end-to-end network status & performance monitoring* • this also can be done in an overlay network • Standardize on over-the-net protocols • riding over standard Internet protocols • proven basis for enabling interoperability

7. Need capabilities to deal with multi-sensor systems: • streaming with low buffering latency • coordinating groups of sources • Need a mechanism for dealing with policy-based filtering technology • firewalls and Network Address Translation (NAT) • routing policy filters • possibly a well-known port that can be approved by management

8. Missing/problematic critical middleware • real-time object request broker • authentication/authorization services • real-time directory services • group coordination/synchronization • session coordination likely is not a problem • Session Initiation Protocol does signaling • automated setup/teardown still needs attention • XML needs a mechanism for network transfer • e.g., Simple Object Access Protocol (SOAP)

9. Implementation Questions • NTP and/or GPS will be needed to provide synchronized network time for XMSF • GPS is more accurate and can be used to synchronize a local NTP master • We believe that Grid and Cluster style network computing will accommodate XMSF without modifications • as long as network capacity is sufficient • A dedicated and monitorable test environment would accelerate development of an XMSF community • use Next Generation Internet networks (Abilene, DREN, etc.) • must be adequately funded for operation • don’t try to take it “out of hide”

10. What We Believe is Available • QoS and multicast can be provided on a private-network basis (probably in NGI) • Performance available off-the-shelf: • individual flows to ~100 Mbps • latency under 100 ms one-way in North America • jitter manageable by buffering, increases latency ~10% • packet loss <1% • High performance end-to-end with instant startup is practical as long as reliable delivery is not needed • TCP does not scale well to wide-area flows above 100 Mbps • Good global synchronization via NTP/GPS • secure NTP may be required in some cases

11. What We Believe is Achievable • QoS on a multi-network basis (but not Internet wide) • the problem is the business case, not the technology • Multicast through overlay networks • VPN • middleware providing application-transparent multicast • Enhanced performance for digital libraries through caching • individual flows ~1 Gbps by localizing access • does not apply to dynamic data exchanged by simulations • Reliable multicast for bulk data transfer

12. Questions for the Symposium at GMU • Who owns the problem of taking up the XMSF challenge? • What sort of forum is best for communication among Web, Net, M&S? • how do you get the right mix of people to participate? • How can distributed learning environments be exploited to help? • What industry and academic activities are ongoing in XMSF? • What sort of DoD programs are likely to engage the XMSF opportunity?

13. Models for Cooperation Among Web, Net, and M&S • Organization model: • A new organization that incorporates all of them • Government program model: • A major DoD program that funds them to work together to create solutions • Conference model: • A forum for cooperation and exchange of information • Focus on solving real problems in XMSF

14. A “Hello World” Exemplar for XMSF • Distribute a Java-based HLA simulation over the Web • Web group provides interface technology and setup/scenario coordination • Net group provides connectivity • despite firewalls • M&S group provides the simulation • Demonstrate at a highly visible event • Make the pieces available for the community experimentation