1 / 13

Network Architecture (R02) - L2

Network Architecture (R02) - L2. Jon Crowcroft, http://www.cl.cam.ac.uk/~jac22 http://www.cl.cam.ac.uk/teaching/1213/R02/. Polyglot Networking. There was a time before the Internet A long, long, long time ago… … … There were other protocol architectures too (gasp!) ISO, CCITT

damian
Download Presentation

Network Architecture (R02) - L2

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. Network Architecture (R02) - L2 Jon Crowcroft, http://www.cl.cam.ac.uk/~jac22 http://www.cl.cam.ac.uk/teaching/1213/R02/

  2. Polyglot Networking • There was a time before the Internet • A long, long, long time ago… … … • There were other protocol architectures too (gasp!) • ISO, CCITT • DECNET, XNS, SNA • CR82, Color Book • How to Interconnect?

  3. Interworking different arch • Application Layer Relay • Transport Service Relay • Protocol Translator • Other? • Future Nets • Internet of Things (e.g. sensors) • Space Networks

  4. Delay Tolerant Networking • Interplanetary Networking • Delays (hours!) • Disruption (solar flares!) • Disconnections (eclipse!) • What would “network” look like?

  5. DTN • Store, Carry, Forward • Like an Email Net • Also like UUCP (Usenet) • Custodians • Routing • Predictable/Schedule (bus, train, spaceship, satellite) • Random? • Errors? FEC, Redundency?

  6. For next week oct 22 • You talk about • ipmc (Ghao Gao) • pgm (Natacha Crooks) • All of you start to read/write about one of • I3, IPNL, ROFL or ILNP • See http://www.cl.cam.ac.uk/teaching/1213/R02/papers/ http://www.cl.cam.ac.uk/teaching/1213/R02/essays/essay0.txt

  7. Multicast - Classic • Make the Internet one big Ethernet • Steve Deering (w/ Dave Cheriton) 1988 • New address (“Class D”) = Host Group, G • Forwarding Scheme = away from S • Prune/Graft per interface “towards” G • Need (S,G) state, Per Router… • State Management…

  8. Group State Management • Implicit • Traffic Driven • Explicit • IGMP Driven • More Overheads! • So not only state overhead is S*G • But also control overhead O(G) messages • Aggregation probably doesn’t do much • Any Source v. Source Specific v. Single

  9. Single Source • Can use reverse path fwd only • Can auth/check source • (exactly same as Best Practice RPF check) • Not much use for many-to-many apps? • N.b. looking at main early use of multicast (“mbone”) - • was many-to-many video conf • main use now? IPTV, Radio, S/W

  10. Reliable Multicast • Seems to be no “one size fits all” • Nack, Ack Aggr & Code based schemes • Need various ordering semantics (if n-m) • Interesting e.g. of new style WG in standards • Did “building blocks” • Then composed RM protocols from these • One v. interesting idea - GRA • minimal router processing engine needed for e2e protocol support • Precursor of other middle box ideas…

  11. RM - Congestion Control & Failures • Two things hard to define • How should multicast flow “compete” with TCP? • What are the “late join”, “early leave” and “fail” semantics for some members? • Again, no “one size fits all” answer…

  12. The “Truth” about Multicast • In fact, in a conference in 2006 • Berkeley Sys Admins reported that • Turning on IP multicast broke Unicast! • Classic deployment dilemma • Specially Bad Case • Multicast has to be in “fast path” • Multicast routing depends closely on Unicast (viz PIM) • It also depended on monitoring data to drive routing update • So new control plane interface to fast path :-(

  13. For next week - oct 22 • 2 of you talk about • Deployment Issues for IP Multicast & • Pragmatic Generalized Multicast • All of you read the two papers • See http://www.cl.cam.ac.uk/teaching/1213/R02/papers/ Don’t forget…for nov 2 http://www.cl.cam.ac.uk/teaching/1213/R02/essays/essay0.txt

More Related