Chapter 08
Upcoming SlideShare
Loading in...5
×
 

Chapter 08

on

  • 3,320 views

 

Statistics

Views

Total Views
3,320
Views on SlideShare
3,314
Embed Views
6

Actions

Likes
2
Downloads
79
Comments
0

1 Embed 6

http://www.slideshare.net 6

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    Chapter 08 Chapter 08 Presentation Transcript

    • CHAPTER EIGHT Routing Protocols
    • Objectives
      • Differentiate between nonroutable, routed and routing protocols
      • Define Interior Gateway Protocols, Exterior Gateway Protocols, distance-vector routing protocols, and link-state routing protocols
      • Explain the concepts of count-to-infinity, split horizon, split horizon with poison reverse, and hold-down timers
      • Describe, configure, and monitor interior routing protocols RIP and IGRP
      • Explain static routing and administrative distance
      • Configure static routing and default routes
    • Nonroutable Protocols Figure 8-1: Early network model using coaxial cable
    • Nonroutable Protocols
      • Peer-to-peer networks
        • Small networks in which each computer can give and receive network services
      • Nonroutable protocols
        • Protocols that do not contain Network layer addressing and therefore can pass between multiple networks
    • Routed Protocols
      • Have packet headers that can contain Network layer addresses
      • Figure 8-2 shows a typical internetwork within which routed protocols are used
      Figure 8-2: Common internetwork
    • Routed Protocols
      • Transmission Control Protocol/Internet Protocol (TCP/IP)
        • Routed protocol stack developed in late 1960s for use on precursor to the Internet
      • Internetwork Packet Exchange/Sequence Packet Exchange (IPX/SPX)
        • Routed protocol stack developed by Novell for use with the Netware network operating system
      • Logical addresses
        • Layer 3 addresses that allow routed protocols to determine which network a particular host is on
    • Routed Protocols Figure 8-3: Common internetwork with IP addresses
    • Routing Protocols
      • Protocols used by routers to make path determination choices and to share those choices with other routers
      Table 8-1: Conceptual route table
    • Routing Protocols
      • Hop count
        • Number of routers a packet must pass through to reach a particular network
      • A metric is a value used to define the suitability of a particular route
      • An autonomous system (AS) is a group of routers under the control of a single administration
    • Routing Protocols Figure 8-4: Big Tin Inc.’s AS
    • Routing Protocols
      • Routing protocols come in two major categories:
        • Interior Gateway Protocols (IGPs)
          • Routing Information Protocol (RIP), Interior Gateway Routing Protocol (IGRP), Enhanced Interior Gateway Routing Protocol (EIGRP), and Open Shortest Path First (OSPF) are examples of IGPs
        • Exterior Gateway Protocols (EGPs)
          • Border Gateway Protocol (BGP) and Exterior Gateway Protocol are examples of EGPs
    • Types of IGP Routing Protocols: Distance-Vector Routing Protocols
      • Broadcast their entire routing table to each neighbor router at predetermined intervals
      Figure 8-5: Distance-vector routing protocol process
    • Types of IGP Routing Protocols: Distance-Vector Routing Protocols
      • Routing by rumor
        • The learning of routes through second-hand information, and not directly from the router experiencing the change
        • One of the main problems with distance-vector routing protocols
      • Convergence
        • A state where all routers on the internetwork share a common view of the internetwork routes
    • Types of IGP Routing Protocols: Distance-Vector Routing Protocols Figure 8-6: Distance-vector convergence example
    • Types of IGP Routing Protocols: Distance-Vector Routing Protocols
      • Problems, such as routing loops, can occur with distance-vector protocols if control measures are not put in place
      • Routing loops
        • Often referred to as count-to-infinity problems
        • Network state in which packets are continually forwarded from one router to another in an attempt to find the destination network
    • Types of IGP Routing Protocols: Distance-Vector Routing Protocols Figure 8-7: Distance-vector convergence problems
    • Types of IGP Routing Protocols: Distance-Vector Routing Protocols
      • Defining a maximum
        • One of the easiest ways to limit count-to-infinity problems
        • Technique used with distance-vector routing protocols to prevent packets from bouncing infinitely throughout an internetwork
          • If you assign a packet a maximum hop count, it cannot bounce infinitely around the internetwork
    • Types of IGP Routing Protocols: Distance-Vector Routing Protocols
      • Two other common ways to prevent routing loops with distance-vector routing protocols:
        • Split horizon
          • A router will not send an update for a route via an interface from which it originally received knowledge of that route
        • Split horizon with poison reverse
          • A split horizon in which the router responds to attempts to updated a route with an update that marks the route in contention as unreachable
    • Types of IGP Routing Protocols: Distance-Vector Routing Protocols
      • Hold-down timer
        • Common technique used to stop routing loops
        • Allows a router to place a route in a state where it will not accept any changes to that route
        • Configurable by the network administrator
        • Can prevent improper route information from being propagated throughout the network
    • Types of IGP Routing Protocols: Link-State Routing Protocols
      • Routers configured with a link-state routing protocol use link-state advertisements (LSAs) to inform neighbor routers on the internetwork
        • Instead of sending entire routing tables, LSAs contain only local links for the advertised router
        • The Shortest Path First (SPF) algorithm uses the link information to compute the routes
        • CPU resources are used instead of bandwidth
    • Types of IGP Routing Protocols: Link-State Routing Protocols
      • Link-state packets (LSPs)
        • Allow every router in the internetwork to share a common view of the internetwork’s topology
      • Flood
        • Process of broadcasting packets onto a network
      • Triggered updates
        • Occur due to network topology changes
    • Types of IGP Routing Protocols: Link-State Routing Protocols Figure 8-8: Link-state advertisements
    • Types of IGP Routing Protocols: Link-State Routing Protocols Table 8-2: Major characteristics of distance-vector and link-state routing protocols
    • Routing Information Protocol
      • A distance-vector routing protocol
      • Has a maximum hop count of 15
      • Hop count is the only metric available for path selection
      • Broadcasts entire routing table to neighbors every 30 seconds
      • Capable of load balancing
      • Easy to configure
    • Routing Information Protocol
      • To install RIP on a Cisco router using TCP/IP, you must perform the following two tasks:
        • Enable RIP
        • Configure RIP for each major network you wish to advertise
      • You need only to configure major network numbers with RIP
        • RIP does not maintain subnet mask information within routing tables it produces
    • Enable RIP Routing Figure 8-9: Sample IP network
    • Configuring RIP Routing for Each Major Network Figure 8-10: Global configuration mode
    • Configuring RIP Routing for Each Major Network
      • Administrative distance
        • Value used to determine reliability of a particular route
      Figure 8-11: Configuring RIP
    • Configuring RIP Routing for Each Major Network Figure 8-12: Output from the show ip route command
    • Configuring RIP Routing for Each Major Network Table 8-3: Administrative distances
    • Show IP Protocol and debug IP Rip Commands Figure 8-13: Output from the show ip protocol command
    • Show Ip Protocol and Debug Ip Rip Commands
      • Flush interval
        • The time at which a route will be totally removed from the routing table if no updates are received
      • The debug ip rip command—like all debug commands—should only be used when troubleshooting RIP
    • Show Ip Protocol and Debug Ip Rip Commands Figure 8-14: Output from the debug ip rip command
    • Show Ip Protocol and Debug Ip Rip Commands Figure 8-15: Output from the show ip route command
    • Show Ip Protocol and Debug Ip Rip Commands Figure 8-16: New output from the show ip route command
    • Show Ip Protocol and Debug Ip Rip Commands Figure 8-17: RIP problems caused by hop count reliance
    • Interior Gateway Routing Protocol (IGRP)
      • Proprietary distance-vector routing protocol created by Cisco
      • Solves some of the problems associated with RIP
      • A larger hop count allows IGRP to be used in larger networks
      • IGRP does not use hops as a metric by default
    • Interior Gateway Routing Protocol (IGRP)
      • Metrics that can be configured for IGRP:
        • Hops
        • Load
        • Bandwidth
        • Reliability
        • Delay
        • MTU
    • Interior Gateway Routing Protocol (IGRP) Figure 8-18: Commands used to configure IGRP
    • Interior Gateway Routing Protocol (IGRP) Figure 8-19: The show ip route command with IGRP
    • Interior Gateway Routing Protocol (IGRP) Figure 8-20: The show ip protocol command with IGRP
    • Interior Gateway Routing Protocol (IGRP) Figure 8-21: Output from the debug ip igrp command
    • Static Routing
      • Stub router
        • Router with only one route
      • Stub network
        • Network with one route to the Internet
      • Static route
        • Route manually added by a network administrator to the routing table of a router
    • Adding Static Routes Figure 8-22: Routing table for RouterC
    • Changing Administrative Distance
      • IP route command also allows you to configure an administrative distance
      • Static routes have a much lower default metric than routes learned by dynamic routing protocols
        • A static route is considered to be a preferred rout since someone took the trouble to enter it
      • If you want the static route to be a back up route to one learned via a dynamic routing protocol, set the administrative distance of the static route higher than that of the default dynamic routing protocol
    • Configuring a Default Route
      • Default route
        • Static route that directs all traffic not specified anywhere else in the routing table to a particular route
        • Configured by the administrator
        • Sometimes called a quad zero route
    • Configuring a Default Route Figure 8-23: Default route example
    • Chapter Summary
      • Protocols vary in their functions
      • Nonroutable protocols are designed to be used in small networks without the need for Network layer addressing
      • Routed protocols were designed with the ability to move between multiple networks via Network layer addressing
      • Routing protocols are classed in two major groups:
        • Interior Gateway Protocols
        • Exterior Gateway Protocols
    • Chapter Summary
      • Interior routing protocols are divided into distance-vector routing protocols and link-state routing protocols
      • Distance-vector protocols periodically broadcast entire routing tables to neighbor routers
      • Link-state protocols broadcast link updates to neighbor routers on the internetwork upon startup and when network topology changes
      • Two common distance-vector IGPs are RIP and IGRP
    • Chapter Summary
      • RIP is an easy-to-configure routing protocol that uses hop count as its sole metric
      • IGRP is not limited to using hop counts as its sole metric
      • Static routes are used to conserve bandwidth and lower memory and CPU load on a router while still allowing for correct routing table creation
      • Static routes give administrators control and flexibility in path selection in a network