Chapter4_Fall2011_IK

Chapter4_Fall2011_IK - Chapter 4: Network Layer Chapter...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 4: Network Layer Chapter goals: understand principles behind network layer services: routing (path selection) dealing with scale how a router works instantiation and implementation in the Internet
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
etwork layer transport segment from sending to receiving host on sending side encapsulates segments into datagrams on receiving side, delivers segments to transport layer network layer protocols in every host, router Router examines header fields in all IP datagrams passing through it network data link physical network data link physical network data link physical network data link physical network data link physical network data link physical network data link physical network data link physical application transport network data link physical application transport network data link physical
Background image of page 2
Key Network-Layer Functions forwarding: move packets from router’s input to appropriate router output routing: determine route taken by packets from source to destination Routing algorithms analogy: routing: process of planning trip from source to destination forwarding: process of getting through single interchange
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
1 2 3 0111 value in arriving packet’s header routing algorithm local forwarding table header value output link 0100 0101 0111 1001 3 2 2 1 Interplay between routing and forwarding
Background image of page 4
Connection setup Important function in some network architectures: ATM, frame relay, X.25 Before datagrams flow, two hosts and intervening routers establish virtual connection Routers get involved Network and transport layer connection service: Network: between two hosts Transport: between two processes
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Network layer connection and connection-less service Datagram network provides network-layer connectionless service VC network provides network-layer connection service Analogous to the transport-layer services, but: Service: host-to-host No choice: network provides one or the other Implementation: in the core
Background image of page 6
Virtual circuits call setup, teardown for each call before data can flow each packet carries VC identifier (not destination host address) everyrouter on source-dest path maintains “state” for each passing connection link, router resources (bandwidth, buffers) may be allocated to VC “source-to-dest path behaves much like telephone circuit” performance-wise network actions along source-to-dest path
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Virtual circuits: signaling protocols used to setup, maintain teardown VC used in ATM, frame-relay, X.25 not used in today’s Internet application transport network data link physical application transport network data link physical 1. Initiate call 2. incoming call 3. Accept call 4. Call connected 5. Data flow begins 6. Receive data
Background image of page 8
Forwarding table 12 22 32 1 2 3 VC number interface number Incoming interface Incoming VC # Outgoing interface Outgoing VC # 1 12 3 22 2 63 1 18 3 7 2 17 1 97 3 87 orwarding table in orthwest router: Routers maintain connection state information!
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/09/2012 for the course CS cs464 at Bilkent University.

Page1 / 95

Chapter4_Fall2011_IK - Chapter 4: Network Layer Chapter...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online