Guide to tcp ip second edition
This presentation is the property of its rightful owner.
Sponsored Links
1 / 49

Guide To TCP/IP, Second Edition PowerPoint PPT Presentation


  • 67 Views
  • Uploaded on
  • Presentation posted in: General

Guide To TCP/IP, Second Edition. Chapter 10 Routing In The IP Environment. Objectives. Understand how basic routing works, how routing tables help control this behavior, and the various types of routing protocols, including distance vector and link-state protocols

Download Presentation

Guide To TCP/IP, Second Edition

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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Guide to tcp ip second edition

Guide To TCP/IP, Second Edition

Chapter 10

Routing In The IP Environment

Guide to TCP/IP, Second Edition


Objectives

Objectives

  • Understand how basic routing works, how routing tables help control this behavior, and the various types of routing protocols, including distance vector and link-state protocols

  • Describe various routing characteristics, including route convergence, split horizon, poison reverse, TTL, and black holes, and understand why they are necessary

  • Understand the interior gateway protocols, such as RIP, OSPF, and EIGRP

Guide to TCP/IP, Second Edition


Objectives cont

Objectives (cont.)

  • Describe how to manage routing on an internetwork, including policy considerations, load balancing, and maintaining a network map

  • Describe factors involved in choosing a routing protocol for your wide area network

Guide to TCP/IP, Second Edition


Objectives cont1

Objectives (cont.)

  • Describe router connections on internal and external networks, including the Internet

  • Understand the importance of securing routers and routing protocols

  • Explain basic router diagnostic troubleshooting concepts, tools, and techniques

Guide to TCP/IP, Second Edition


Understanding routing

Understanding Routing

  • Routing table

    • Database that lives in the memory of the router

    • Entries in this database are known as “routes”

    • Network addresses

    • “next hop”

    • Metrics

    • Vendor-specific information

    • Compilation of information about all the networks that the router can reach

Guide to TCP/IP, Second Edition


Understanding routing cont

Understanding Routing (cont.)

Guide to TCP/IP, Second Edition


Understanding routing cont1

Understanding Routing (cont.)

  • The routing table is used as follows:

    • Router reads destination address

    • Looks in the Network field of its routing table for a match

    • Finds a match, then it sends the packet to the corresponding next hop

Guide to TCP/IP, Second Edition


How entries are placed in the routing table

How Entries Are Placed in the Routing Table

  • Route entries can be placed in a routing table in three basic ways:

    • Direct connection

    • Manually configured

      • Exact configuration

      • Simple and secure

    • Dynamically with a routing protocol

      • Network Layer Reachability Information (NLRI)

Guide to TCP/IP, Second Edition


Routing protocols and routed protocols

Routing Protocols and Routed Protocols

  • Routing protocols are used to exchange routing information

    • Routing Information Protocol (RIP)

    • Open Shortest Path First (OSPF)

  • Routed protocols are Layer 3 protocols that are used to get packets through an internetwork

    • Internet Protocol (IP)

    • Internetwork Packet Exchange (IPX)

Guide to TCP/IP, Second Edition


Grouping routing protocols

Grouping Routing Protocols

  • Two primary ways to group routing protocols

    • Routing domains or autonomous systems

      • Interior gateway protocols (IGPs)

      • Exterior gateway protocols (EGPs)

    • Functionality of routing protocols

      • Distance vector

      • Link-state

Guide to TCP/IP, Second Edition


Distance vector routing protocols

Distance Vector Routing Protocols

  • Route by rumor

  • Periodically broadcast entire routing table

  • Considered “chatty”

  • Routing decisions are based on network distance

    • Routing Information Protocol (RIP)

    • Interior Gateway Routing Protocol (IGRP)

    • Border Gate Protocol (BGP)

Guide to TCP/IP, Second Edition


Distance vector routing protocols cont

Distance Vector Routing Protocols (cont.)

Guide to TCP/IP, Second Edition


Routing loops

Routing Loops

  • One router believes the best path to a network is via a second router, and at the same time, the second router believes the best path to that network is through the first router

  • TTL

Guide to TCP/IP, Second Edition


Loop avoidance schemes

Loop-Avoidance Schemes

  • Count to infinity

  • Network diameter

  • IP header TTL field

  • Split horizon

  • Poison reverse

Guide to TCP/IP, Second Edition


Link state routing protocols

Link-State Routing Protocols

  • Generates information about directly connected neighbors

  • Flood network (update) with information

    • Update only when a link change is detected

  • All routers have identical view of network topology

    • Convergence time is short

  • Dijkstra algorithm

  • Build adjacencies with neighbor routers

Guide to TCP/IP, Second Edition


Link state routing protocols cont

Link-State Routing Protocols (cont.)

Guide to TCP/IP, Second Edition


Routing characteristics

Routing Characteristics

  • Route convergence

    • Loop-free path to all networks

  • Time to Live (TTL)

    • Defined in the Network layer header

  • Multicast vs broadcast update behavior

Guide to TCP/IP, Second Edition


Routing characteristics cont

Routing Characteristics (cont.)

  • ICMP router advertisements

    • Allow hosts to passively learn about available routes

  • Areas, autonomous systems, and border routers

Guide to TCP/IP, Second Edition


Routing characteristics cont1

Routing Characteristics (cont.)

Guide to TCP/IP, Second Edition


Routing characteristics cont2

Routing Characteristics (cont.)

Guide to TCP/IP, Second Edition


Routing characteristics cont3

Routing Characteristics (cont.)

Guide to TCP/IP, Second Edition


Interior gateway protocols

Interior Gateway Protocols

  • RIP

    • RIPv1, RIPv2

    • Distance vector routing protocol

    • UDP based

    • UDP port 520

  • RIPv2

    • Support for variable-length subnets

Guide to TCP/IP, Second Edition


Ripv1

RIPv1

  • Broadcast routing table every 30 seconds

  • Does not support non-default subnet masks

  • A RIP packet can have up to 25 networks

  • RIPv1 packet format:

    • Command

    • Version

    • Reserved (or Zero)

    • Address Family Identifier

    • IP Address

    • Metric

Guide to TCP/IP, Second Edition


Ripv1 cont

RIPv1 (cont.)

Guide to TCP/IP, Second Edition


Ripv1 cont1

RIPv1 (cont.)

Guide to TCP/IP, Second Edition


Ripv2

RIPv2

  • Support of variable-length subnet masks

  • Basic authentication

  • Multicasts routing updates

  • RIPv2 packet format

    • Command

    • Version

    • Reserved

    • Address Family

    • Authentication Type

Guide to TCP/IP, Second Edition


Ripv2 cont

RIPv2 (cont.)

  • RIPv2 packet format (cont.)

    • Authentication

      • Plain text and encrypted passwords

    • Address Family Identifier

    • Route Tag

      • Internal route entry, external route entry

    • IP Address

    • Subnet Mask

    • Next Hop

    • Metric

Guide to TCP/IP, Second Edition


Ripv2 cont1

RIPv2 (cont.)

Guide to TCP/IP, Second Edition


Open shortest path first

Open Shortest Path First

  • Link-state routing protocol

  • Non-proprietary

  • Configurable metrics

  • Multicast Hello packets

  • Establish adjacencies

Guide to TCP/IP, Second Edition


Open shortest path first cont

Open Shortest Path First (cont.)

  • Dijkstra algorithm

  • Designated router (DR)

  • Backup designated router (BDR)

  • Link State Advertisements (LSA)

  • LSA multicast to DR (224.0.0.6)

Guide to TCP/IP, Second Edition


Open shortest path first cont1

Open Shortest Path First (cont.)

Guide to TCP/IP, Second Edition


Open shortest path first cont2

Open Shortest Path First (cont.)

  • Six types of LSAs

    • Type 1 (Router Links Advertisement)

    • Type 2 (Network Links Advertisement)

    • Type 3 (Network Summary Link Advertisement)

    • Type 4 (AS Boundary Router Summary Link Advertisement)

    • Type 5 (AS External Link Advertisement)

    • Type 7 (Not So Stubby Area Networks Advertisement)

Guide to TCP/IP, Second Edition


Open shortest path first cont3

Open Shortest Path First (cont.)

Guide to TCP/IP, Second Edition


Open shortest path first cont4

Open Shortest Path First (cont.)

  • OSPF header fields

    • Version Number Field

    • Type Field

    • Packet Length Field

    • Router ID Field

    • Area ID Field

    • Checksum Field

    • AuType Field

    • Authentication

Guide to TCP/IP, Second Edition


Open shortest path first cont5

Open Shortest Path First (cont.)

Guide to TCP/IP, Second Edition


Enhanced interior gateway routing protocol eigrp

Enhanced Interior Gateway Routing Protocol (EIGRP)

  • Developed by Cisco in 1980s (IGRP)

  • Updated to EIGRP in early 1990s

  • Hybrid routing protocol

  • Integrates distance vector and link-state functions

Guide to TCP/IP, Second Edition


Enhanced interior gateway routing protocol eigrp cont

Enhanced Interior Gateway Routing Protocol (EIGRP) (cont.)

Guide to TCP/IP, Second Edition


Border gateway protocol

Border Gateway Protocol

  • Exchange routing information between separate autonomous systems

  • BGP offers three types of routing operations

    • Inter-autonomous system routing

    • Intra-autonomous system routing

    • Pass-through autonomous system routing

Guide to TCP/IP, Second Edition


Border gateway protocol1

Border Gateway Protocol

Guide to TCP/IP, Second Edition


Securing routers and routing behavior

Securing Routers And Routing Behavior

  • Turn off unnecessary services, shut down unnecessary listening ports

  • Configure strong access security to prevent tampering, and, of course, secure physical access to the boxes

  • Assign secure encrypted passwords

  • Telnet sends unencrypted login names and passwords

  • Use secure routing protocols

Guide to TCP/IP, Second Edition


Troubleshooting ip routing

Troubleshooting IP Routing

  • Test connectivity with the following tools

    • ROUTE: Used to view the host’s local routing table, and add and remove route entries

    • PING

    • TRACERT

    • PATHPING

Guide to TCP/IP, Second Edition


Chapter summary

Chapter Summary

  • Routing protocols and routers provide a mechanism that can forward traffic from a sender’s subnet to an intended receiver’s subnet

  • Generally, routers depend on access to tables of information that describe known routes and default routers so that traffic can be directed properly within any given internetworked environment, or forwarded outside that environment for delivery elsewhere

Guide to TCP/IP, Second Edition


Chapter summary cont

Chapter Summary (cont.)

  • Routers depend on various routing protocols to manage the packet forwarding process

  • Interior routing protocols are designed for use within autonomous routing domains, such as those that fall under the purview and control of a single company or organization

  • Exterior routing protocols provide a means whereby routers belonging to multiple companies or organizations can safely and securely forward data and manage routing information amongst the parties involved in a common connection

Guide to TCP/IP, Second Edition


Chapter summary cont1

Chapter Summary (cont.)

  • Distance vector routing protocols such as RIP represent the oldest and simplest type of routing protocols, in which the number of router transitions (called hops) provides a crude metric of routing cost, and where no routing loops should occur as part of the routing topology

  • Link-state routing protocols like OSPF provide more sophisticated routing metrics and controls, and not only can deal with multiple routes between a sender and receiver, but can also use more powerful route metrics to balance loads across such links, or failover from less expensive to more expensive routes, as needed

Guide to TCP/IP, Second Edition


Chapter summary cont2

Chapter Summary (cont.)

  • The OSPF protocol supports much more sophisticated routing structures that break up a network into routing areas to help optimize routing tables and behavior

  • In addition, OSPF recognizes special categories of routing areas, such as a backbone area (where all individual areas interconnect) and autonomous systems, which represent individual routing regions that fall under specific administrative and management control

  • In such cases, area border routers may connect separate routing areas to the backbone, or to other routing areas

Guide to TCP/IP, Second Edition


Chapter summary cont3

Chapter Summary (cont.)

  • Routing characteristics, which determine how long it takes route information (and changes) to stabilize within a group of routers that share information, help to determine what kinds of routing protocols to use in specific applications

  • One important characteristic is convergence (how long it takes routing protocols to calculate optimal routes following updates), including techniques such as split horizon, poison reverse, and Time to Live settings

  • Other important characteristics include information update mechanisms, Router Advertisements, and how routing domains may be logically subdivided to help manage complexity and reduce router traffic

Guide to TCP/IP, Second Edition


Chapter summary cont4

Chapter Summary (cont.)

  • Managing routing on a complex network means understanding how and when to use exterior and interior routing protocols, and how to establish the right kinds of connections between multiple routing domains

  • Private WAN links, Internet connections, and Mobile IP users all require special handling where routing is concerned to make sure that systems and services behave as required

  • It’s especially important to understand how and when interior routing protocols, such as OSPF, must interoperate with exterior routing protocols, such as BGP

Guide to TCP/IP, Second Edition


Chapter summary cont5

Chapter Summary (cont.)

  • Because router tables define the topology and behavior of IP networks, it’s essential to manage router security and updates as safely as possible

  • For those reasons, using strong passwords and secure links to access and update routers and their configurations is absolutely essential

Guide to TCP/IP, Second Edition


Chapter summary cont6

Chapter Summary (cont.)

  • Key troubleshooting tools for inspecting and diagnosing routing problems through a Windows 2000 and Windows XP IP host include ROUTE,TRACERT, PING, and PATHPING

  • To become as proficient in managing routes and routers as possible, make yourself completely familiar with these command-line utilities

Guide to TCP/IP, Second Edition


  • Login