1 / 18

Foundations of Networking Part 2

Explore the fundamentals of networking, including communication pathways, networks, internetworks, routers and gateways. Learn about multiplexing and different strategies for packet switching. Discover the implementation of logical and statistical multiplexing in networks.

radams
Download Presentation

Foundations of Networking Part 2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Foundations of NetworkingPart 2 Networking CS 3470, Section 1 Sarah Diesburg

  2. The Big Picture • A communication pathway is a link between two or more nodes • A network is a collection of path-connected communication pathways • Book's definition: A network is a construction of nesting networks, where at the bottom level, the network is implemented by some physical medium. A bit awkward, but motivates “the cloud.”

  3. The Network • Nodes on the inside implement the network [switches, routers, and gateways] • Nodes on the outside use the network [hosts]

  4. The Internetwork • “Clouds helping clouds” would form an internetwork, or—you guessed it—an Internet.

  5. Network Glue • A node that is connected to two or more networks and conveying packets from one to another is referred to as a router or a gateway • Also does packet switching, but different than a switch

  6. Where’s Waldo • Where are the routers/gateways?

  7. Where’s Waldo • Where are the switches?

  8. Where’s Waldo • Where are the end hosts?

  9. Network Glue • Just because there are links doesn't mean that there's a network. Routing requires destination recognition, which requires addressing. • Unicast (me send to you) requires addressing, whereas broadcast (me send to all) doesn't. • How about multicast? (me send to group)

  10. Multicast • Multicast occurs when a node wants to send a message to some subnet of the other nodes • Streaming media and Internet TV • In actual practice, doesn’t scale well

  11. Multiplexing • Much like timesharing of a CPU, data links can be multiplexed over the physical links of a network. • Recall the difference between circuit switching and packet switching?

  12. Circuit Switching • In circuit switching, there are only so many dedicated links

  13. Circuit Switched Networks • All resources (e.g. communication links) needed by a call dedicated to that call for its duration • Example: telephone network

  14. Packet Switching • Can handle multiple “streams” at once • Sharing system resources among multiple users is called multiplexing. • Multiplex onto switch 1 vsdemultiplex off switch 2

  15. Multiplexing • Synchronous Time-Division Multiplexing (STDM) is when you get the whole link, but only for specific time quantum. • If there are 4 sending hosts, the switch cycles through 4 quantums (even if some of the hosts are quiet)! • Frequency-Division Multiplexing (FDM) is when you get an always-available stream, but it's only a portion of the entire spectrum (like TV channels) • But how do you add a new stream once all the portions are used?

  16. Multiplexing • Statistical multiplexing overcomes those challenges • Link is shared over time • Flow is on-demand, not by necessarily by “reservation”

  17. Multiplexing Scheduling Strategies • How do we choose which packet to send next? • First In, First Out (FIFO) • Priority • Need to worry about starvation • Round Robin • How would this be implemented in STDM vs statistical multiplexing?

  18. Multiplexing • A lot of multiplexing is logical, statistical or aggregate. • For example, in ATM networks, you might get a guaranteed 10% peak rate by earmarking one out of every 10 frames to your channel. The 10% rate is a logical rate (like FDM), but the implementation is through STDM.

More Related