# Presentation: 158486

## Networking 1 A crash course in networking (Because Networking 101 requires more time)

## Network Design Triangle

- © 2004 Syzygy Engineering  – Will Ivancic

## Protocol Stack

- TCP, UDP, SCTP, etc...

- Wire, Fiber, RF, etc...

**OSI Model**

- Application

- Transport

- Data Link

- Physical

**TCP/IP  Model**

- IPv4, IPv6

- IEEE 802, SONET
- Frame Relay (HDLC), etc...

- E-Mail, FTP,
- Web Browsing, etc...

## CCSDS relationship with the OSI Layers

## Slide 5

## Network Layers

- Why Layering?
- Flexibility
- Extensibility
- Divide and conquer
- Transport Layer
- Protocols to move data between end systems
- Network Layer
- End-to-End addressing
- Routing and Forwarding
- Data Link Layer
- Point-to-Point addressing
- Maps Network to physical layers
- Provides media access (CDMA, TDMA, FDMA, Collision Sense Multiple Access, Aloha)

## Why all the confusion with TCP?

- TCP/IP (Transmission Control Protocol/Internet Protocol Suite)
- A suite of protocols
- Over 4000 Request for Comments (RFCs)
- NOTE! Often times the term TCP is used as short hand for the TCP/IP protocol Suite.  Lately, an attempt has been made to use IP for identify the TCP/IP protocols suite to alleviate the confusion between the TCP/IP suite and TCP the transport protocol.
- TCP (Transmission Control Protocol)
- A Reliable Transport Protocol
- Designed for fairness
- Optimized for shared links
- Congestion Control (Multiplicative Decrease / Additive Increase)
- Self-Probing to discover link capacity
- Delay and bandwidth sensitive (bandwidth/delay product)
- UDP (User Datagram Protocol)
- An Unreliable Transport Protocol
- No Congestion Control
- Insensitive to delay
- IPv4 and IPv6 (Internet Protocol version 4 and Internet Protocol version 6)
- Internet Protocols used to identify and route packets
- Source and Destination Addresses
- Quality of Service Bits
- Hop Count (Used to keep packets from propagating continuously
- IP is insensitive to delay

## Routing

- Dynamic Routing is a service (application)
- Types/Terms
- Default (Route of last resort)
- Static (Predetermined)
- Dynamic
- Interior Gateway Protocols
- RIP (Routing Information Protocol)
- Small Networks
- Open Shortest Path First (OSPF)
- Many additional metrics available
- Widely used in large networks (e.g. DoD, Businesses, Universities)
- Exterior Gateway Protocols
- BGP (Boarder Gateway Protocol)
- Used in the Big Internet such as between ISPs (Internet Service Providers)
- MANETs (Mobile Ad hoc NETworks)
- Self-configuring and self-organizing network of mobile nodes usually connected via wireless links
- Proactive routing protocols Optimized Link State Routing (OLSR), Open Shortest Path First (OSPF) extension
- Applicable for relatively stable  networks
- Suitable for large and dense networks
- Reactive routing protocol Ad Hoc On-Demand Distance Vector (AODV), Dynamic Source Routing protocol (DSR), Dynamic MANET On-demand (DYMO)
- Applicable to highly dynamic networks

## Delay/Disruption Tolerant Networking (DTN)

- DTN
-   Opportunistic
- Low delay
*Possibly* no need to schedule assets

- DTN
-   Long delays
-   Need to schedule assets

- DTN is really an application overlay that has
- aspects of scheduling, data transport and routing.

## Network Security

- Where
-  Data/Application
- End-to-End
- Transport
- Transport Layer Security (TLS)
- End-to-End
- Network
- IPsec (IP Security)
- End-to-End
- Data-Link Layer (Bulk Encryption)
- Point-to-Point

- Key Types
- Symmetric
- Pre-placed Keys
- Insensitive to delay
- Asymmetric
- Public Key Infrastructure (PKI)
- Generally sensitive to delay
- Issues
- Key Management
- Policy Management
- ITAR

## Network – Rules of Thumb

**Metcalfe's law**:  The value of a telecommunications network is proportional to the square of the number of users of the system (N2).   Actually N(N-1)/2
- Internet,World Wide Web Operating systems, Applications, Social networking
**Andrew Odlyzko’s and Benjamin Tilly’s law**:   The value of a network with N members is not n squared, but rather  N x log(N)
-  Reason: Not all potential connections in a network are equally valuable.
**Reed's law:** the utility of large networks, particularly social networks, can scale exponentially with the size of the network.
- The number of possible sub-groups of network participants is 2N-N-1 , where N is the number of participants. This grows much more rapidly than either
- the number of participants, N,
- or the number of possible pair connections, N(N-1)/2
- Even if the utility of groups available to be joined is very small on a per-group basis, eventually the network effect of potential group membership can dominate the overall economics of the system

## Summary and Important Information

- Network design entails Policy, Protocols and Architecture
- Protocols are tools
- Be sure to apply the proper tool relative to the environment being used.
- TCP/IP is a suite of international commercial-off-the-shelf protocols
- Protocols that require handshaking or a response/replay do not work over long delays and intermittently connected networks
- Protocols that require infrastructure may not necessarily be applicable to space unless caching of information is used.
- Many TCP/IP protocols are delay insensitive and can be utilized in a variety of environments.
- Default routes and Static routes can get one in trouble – be careful
- One of the great powers of COTS products is the debugging tools
- There was an excellent tutorial on the distinctions between routing, switching, and bridging at the following URL:
- http://www3.ietf.org/proceedings/06mar/slides/rbst-0.pdf