Moving Real-time Data Across Complex Networks. Using an established protocol versus a DIY approach

Transcription

1 Moving Real-time Data Across Complex Networks Using an established protocol versus a DIY approach

2 Moving Real-time Data Across Complex Networks 1 Choosing an approach TCP and UDP are the Most Common Transport Protocols on IP Networks TCP UDP When transporting critical real-time and latency sensitive data across complex networks, both TCP and UDP may be bad choices Slow, reliable transfer - - Web browsing Fast, non-reliable transfer - VOIP - Streaming Music If you need both fast and reliable, what are your choices?

3 Moving Real-time Data Across Complex Networks 2 Choosing an approach I ve heard that Internet Engineering Task Force (IETF) has RFCs that can address the limitations of TCP and UDP. What are they and what do they give you?

4 Moving Real-time Data Across Complex Networks 3 Choosing an approach What is the IETF? The Internet Engineering Task Force (IETF) is a community of network designers, operators, vendors, and researchers concerned with the Internet architecture and its smooth operation. Its mission is to make the Internet work better. What is an RFC? A Request for Comments (RFC) is a formal document from the IETF that is the result of committee drafting. Some RFCs are informational in nature, others are intended to become Internet standards.

5 Moving Real-time Data Across Complex Networks 4 Choosing an approach For our purposes, there are two types of RFCs Advice and Protocols Learn Build Iterate Integrate Test Advice: best practices for developers that are creating protocols Protocol: a complete end-to-end solution (for a specific problem)

6 A Quick Look At 3 RFCs Advice RFCs cover specific issues for building a protocol. The full design, coding, integration, and testing is still left to the user. How hard is creating a complete protocol?

7 Protocol design What is a Protocol? Moving Real-time Data Across Complex Networks 6 A protocol is a set of rules and conventions that assures successful communication It includes: Mechanisms for devices to identify and connect with each other Formatting rules for packaging data into messages that are sent and received Preexisting agreement for information structure, and ways to send and receive it

8 Moving Real-time Data Across Complex Networks 7 Protocol design Key Elements of a Protocol Syntax Format or structure of the data. Example: first 8 bits represent the sender address, next 8 bits represent the receiver address, the rest is data. Meaning of each section. How a particular pattern is to be interpreted, actions to take based on the interpretation. Semantic Timing When should data be sent? How fast can it be set?

9 Moving Real-time Data Across Complex Networks 8 Look at the complexity of an example protocol. Connection is just one function of a protocol: Typical Protocol Functions Addressing TCP: Connection State Complexity 12 Unique Connection States 17 Transition Events Connection Reliability Flow Control Security

10 Moving Real-time Data Across Complex Networks 9 Look at the complexity of an example protocol. Flow Control is another function of a protocol: Typical Protocol Functions Addressing TCP: Flow Control Complexity Includes: Slow start, Congestion Avoidance, Fast Recovery There are at least 19 Congestion Avoidance algorithms TCP Cubic One of 19 Congestion Avoidance Algorithms listed on Wikipedia Connection Reliability Flow Control Security

11 Moving Real-time Data Across Complex Networks 10 Protocol design Protocol Layer Interactions Protocols are constructed in layers. A thorough understanding of each layer, and the interactions between layers is a requirement for a successful protocol. How are frame boundaries presented to the application? Will UDP checksums guarantee data integrity? What DSCP/TOS flags are appropriate? How will IP Fragmentation affect performance? How will ether frame CRCs impact upper layers? Does 8b/10b encoding provide error checking?

12 Moving Real-time Data Across Complex Networks 11 OK, designing a protocol is complicated What about implementing a proven protocol?

13 Moving Real-time Data Across Complex Networks 12 Protocol implementation Reliability Every line of code is a potential point of failure. Requirements Lack of user input or even knowing the users. Users don't know what they want until they see it. React Its has to interact with unknown, low quality software. All software is affected by external factors. Reckoning Estimating scope, effort, cost is an art not a science. Software is Hard

14 Moving Real-time Data Across Complex Networks 13 Protocol implementation Validating and Testing Protocol Implementation Types of Protocol Testing: Bandwidth: Rate of packets transmitted Correctness: Receive expected packets Latency: Time to receive a packet Performance Testing: Stress, load, reliability testing Functional Testing: Behavioral testing Negative testing Conformance testing Interoperability testing Network testing

15 Moving Real-time Data Across Complex Networks 14 Protocol implementation What does it cost to implement a new protocol? An estimate to build a messaging protocol is about 400 development man hours Coding is only 5% of the total lifecycle cost, Total lifecycle cost: 8,000 man hours Development costs between $75/hr and $150/hr The project cost to develop a new protocol is $600,000 to $1,200,000.

16 Moving Real-time Data Across Complex Networks 15 Protocol implementation Most people are best served by choosing a proven implementation

17 Moving Real-time Data Across Complex Networks 16 Choosing a Protocol Protocol Requirements When choosing a protocol for strategic applications with demanding data transport, look at these 6 criteria: Reliable Delivers the correct data in the correct order High throughput High bandwidth data is delivered over long-haul links Latency sensitive Data is transported in a timely fashion Performant Delivers benefits on networks with packet loss, reordering, duplication, jitter, and drop outs Flexibility Latency, overhead, and error correction can be traded to fit mission requirements Visibility Insight into network impairments and impacts are reported

18 Moving Real-time Data Across Complex Networks 17 Choosing a Protocol TCP Variants TCP-Cubic TCP-Illinois SCPS-TP SCTP Emphasize TCP goals like congestion avoidance and reliability, while improving performance Protocols to Consider Reliable UDP RUDP UDT ENET NORM SMPTE Add some reliability to inherently unreliable UDP Commercial DataDefender FASP MPT SpeedyPackets Optimize transport for target applications

19 Moving Real-time Data Across Complex Networks 18 Choosing a Protocol Applications with critical real-time or streaming data are poorly served by TCP and UDP. The best alternative is an optimized protocol with a quality implementation. Look for the next piece in the series: Choosing a Transport Protocol for Real-time Data from

20 For more information, visit: Kratos RT Logic Moving Real-time Data Across Complex Networks 19