ccna routing protocol

Upload: mora-joram

Post on 02-Apr-2018

251 views

Category:

Documents


2 download

TRANSCRIPT

  • 7/27/2019 CCNA routing protocol

    1/20

    2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    ITE PC v4.0

    Chapter 1 1

    Link-State Routing

    Protocols

    Routing Protocols andConcepts Chapter 10

  • 7/27/2019 CCNA routing protocol

    2/20

    ITE PC v4.0

    Chapter 1 2 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Objectives Describe the basic features & concepts of link-state

    routing protocols.

    List the benefits and requirements of link-state routingprotocols.

    Key Terms

    Link-state Routing Protocol

    Shortest Path First

    Link-state Packet

    Link-state Database

  • 7/27/2019 CCNA routing protocol

    3/20

    ITE PC v4.0

    Chapter 1 3 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Whos Responsible for Link-State Protocols?

    Dijkstra's algorithm, solves the single-source shortestpath problem for a directed graph with nonnegativeedge weights.

    Wikipidia

    Edsger Dijkstra

  • 7/27/2019 CCNA routing protocol

    4/20

    ITE PC v4.0

    Chapter 1 4 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Link-State Routing Protocols

    Also known as shortest path first algorithms

    These protocols built around Dijkstras SPF

  • 7/27/2019 CCNA routing protocol

    5/20

    ITE PC v4.0

    Chapter 1 5 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Difference Between LS and DV Protocols

    Distance Vector protocols understand distant networksbased on direction (example: signs)

    Link State protocols create a topology (example: map)

  • 7/27/2019 CCNA routing protocol

    6/20

    ITE PC v4.0

    Chapter 1 6 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Step 1: Determine Connected Networks

    Router identifies directlyconnected networks

    Includes:

    Link - Router Interface

    State - Information aboutthe condition of the links

  • 7/27/2019 CCNA routing protocol

    7/20ITE PC v4.0

    Chapter 1 7 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Step 2: Establish Neighbor Adjacencies

    Hello packets are exchangedbetween routers with connectedinterfaces

    Once routers learn it has neighbors

    they form an adjacency

    - Two adjacent neighbors willexchange hello packets

    -These packets will also serve as

    keep alives Verify that neighbor and stateshave not changed

  • 7/27/2019 CCNA routing protocol

    8/20ITE PC v4.0

    Chapter 1 8 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Step 3: Builds the Link-State Packet

    Each router builds its ownLink State Packet (LSP)

    Contents of LSP:

    - State of each directlyconnected link

    - Includes informationabout neighbors such as

    neighbor ID, link type, &bandwidth.

  • 7/27/2019 CCNA routing protocol

    9/20ITE PC v4.0

    Chapter 1 9 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Step 4: Flooding LSPs to Neighbors

    Once LSP are created they are forwarded out toneighbors

    Neighbors store the LSPs in a database

    After receiving the LSPs, the neighbor continues toforward it throughout routing area

  • 7/27/2019 CCNA routing protocol

    10/20ITE PC v4.0

    Chapter 1 10 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Flooding LSPs to Neighbors (2)

    LSPs are sent out under the following conditions

    -Initial router start up or routing process

    -When there is a change in topology

  • 7/27/2019 CCNA routing protocol

    11/20ITE PC v4.0

    Chapter 1 11 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Step 5: Constructing a Link State Topology

    Routers use a database to construct a topology map ofthe network

    Best path selected from topologyand placed in routing table

  • 7/27/2019 CCNA routing protocol

    12/20ITE PC v4.0

    Chapter 1 12 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Sample Exchange of LSPs

  • 7/27/2019 CCNA routing protocol

    13/20

    ITE PC v4.0

    Chapter 1 13 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Shortest Path First (SPF) Tree

    Building a portion of the SPF treeProcess begins by examining R2s LSP information

    -R1 ignores 1st LSP

    Reason: R1 already knows its connected to R2

  • 7/27/2019 CCNA routing protocol

    14/20

    ITE PC v4.0

    Chapter 1 14 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Shortest Path First (SPF) Tree

    Building a portion of the SPF tree-R1 uses 2nd LSP

    Reason: R1 can create a link from R2 to R5.This information is added to R1s SPF tree

  • 7/27/2019 CCNA routing protocol

    15/20

    ITE PC v4.0

    Chapter 1 15 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Shortest Path First (SPF) Tree

    Building a portion of the SPF tree-R1 uses 3rd LSP

    Reason: R1 learns that R2 is connected to10.5.0.0/16.

    This link is added to R1s SPF tree.

  • 7/27/2019 CCNA routing protocol

    16/20

    ITE PC v4.0

    Chapter 1 16 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Link-State Routing Path Determination

    Determining the shortest path

    The shortest path to a destination determined by adding thecosts & finding the lowest cost

  • 7/27/2019 CCNA routing protocol

    17/20

    ITE PC v4.0

    Chapter 1 17 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Link-State Routing Table

    Once the SPF algorithm has determined the shortestpath routes, these routes are placed in the routingtable.

  • 7/27/2019 CCNA routing protocol

    18/20

    ITE PC v4.0

    Chapter 1 18 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Routing Protocols Comparison Table

    Routing

    protocol

    Builds

    Topologicalmap

    Router can

    independentlydetermine the

    shortest path to

    every network.

    Convergence

    A periodic/

    event drivenrouting updates

    Use

    ofLSP

    Distance

    vector

    No No Slow Generally No No

    Link State Yes Yes Fast Generally Yes Yes

    Advantages of a Link-State Routing Protocol

  • 7/27/2019 CCNA routing protocol

    19/20

    ITE PC v4.0

    Chapter 1 19 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

    Link-State Hardware Requirements

    Memory requirements

    Typically link state routing protocols use morememory

    Processing Requirements

    More CPU processing is required of link staterouting protocols

    Bandwidth Requirements

    Initial startup of link state routing protocols canconsume lots of bandwidth

  • 7/27/2019 CCNA routing protocol

    20/20

    ITE PC v4.0

    Link State Routing Protocols

    Two link state routing protocols used for routing IP

    -Open Shortest Path First (OSPF)

    -Intermediate System-Intermediate System (IS-IS)