CCNP(TM) Routing Study Guide (Exam 640-503)

, McGraw-Hill Companies

ISBN:0072125438, Edition: Stg, 2000-11-27

Price: $49.99

Contents

1 IP Routing Fundamentals
Routing Information Protocol
Interior Gateway Routing Protocol
Enhanced Interior Gateway Routing Protocol
Open Shortest Path First Protocol
Border Gateway Protocol
What Is Routing?
Routing Metrics
Default Route
Load Balancing
Administrative Distance
Requirements for IP Routing
Enabling IP Routing
Assigning an IP Address
Making Sure the Destination Network Is Present in the Routing Table
Making IP Routing Work
The Two Major Functions of Routing
Gathering and Disseminating Routing Information
Switching Packets from Inbound Interface to Outbound Interface
Classful vs. Classless Routing
What Is Classful Routing?
The IP CLASSLESS Command
Distance-Vector Routing Protocol Characteristics
Increased Convergence Time
Routing Loops
Unreachable Networks
Increased Broadcasts
Distance-Vector Routing Protocols
Configuring IGRP
Link-State Routing Protocol Characteristics
The Link-State Routing Protocols
Link-State Routing Protocols vs. Older Distance-Vector Protocols
Convergence Issues for IP Routing Protocols
RIP Convergence
IGRP Convergence
EIGRP Convergence
OSPF Convergence

2 IP Addressing Issues

RFC 950: IP Subnet Masking
RFC 1518: Route Summarization
RFCs 1519 and 2050: Classless Interdomain Routing
RFC 1631: Network Address Translation
RFC 1812: Variable-Length Subnet Masks
RFC 1918: Address Allocation for Private Internets
IP Address Classes
The Class A Range
The Class B Range
The Class C Range
The Class D Range
The Class E Range
RFC 1918: Private Address Space
Subnetting Overview
Subnetting and Its Benefits
(S)From the Classroom
Binary Math Troubles
Issues with IP Addressing
Lack of Real Address Space: IP Address Exhaustion
Size of the Routing Table
What Is Hierarchical Addressing?
Benefits of Hierarchical Addressing
IP Addressing Choices
Simple Subnetting
Complex Subnetting
Variable-Length Subnet Masking
Review of Complex Subnetting
Variable-Length Subnet Masking
What Is Route Summarization?
Performing Summarization Within an Autonomous System
Performing Summarization Between Autonomous Systems Using CIDR
Considerations for Summarization
Ensuring the Contiguous Block of Addresses
Ensuring the Same Highest-Order Bits for All Networks
Ensuring the Block of Addresses Falls on a Power of 2, Bit Boundary
Rules for Summarization
How Classful Routing Protocols Affect Network Boundary Summarization
Classless Routing Protocols Perform Prefix-Based Routing
Classless Routing Protocols Use Longest Match for Route Selection
Route Summarization Walkthrough
Walkthrough Using a Binary Example
Classless Interdomain Routing
CIDR Walkthrough
The IP UNNUMBERED Command
The IP HELPER-ADDRESS Command
The IP HELPER-ADDRESS and IP FORWARD-PROTOCOL Command Syntax
Default Broadcasts
Walkthrough of a DHCP Exchange

3 OSPF Operation and Configuration for a Single OSPF Area

Scalability
Flexibility
Summarized Advertisements
VLSM
Incremental Routing Updates
Faster Routing Convergence
OSPF Benefits
Other Benefits
Decision Making
The Complete Picture
OSPF Concepts
Neighbor Relationships
Adjacency
Designated Router and Backup Designated Router
OSPF Tables
OSPF Neighbor Relationships
Building an OSPF Neighbor Relationship
Behavior of Various Media Types
Hello Packet Description and Important Fields
Elements That Must Match for a Neighbor Relationship to Happen
DR and BDR Election
The IP OSPF PRIORITY Command
OSPF States in Building a Neighbor Relationship
The DOWN State
The INIT State
The Two-way/Exstart State
The Two-way/EXCHANGE State
Two-way/LOADING State
The FULL State
OSPF Packet Types
Hello (Type 1) Packets
Database Description (Type 2) Packet
Link-State Request (Type 3) Packets
Link-State Update (Type 4) Packets
Acknowledge (Type 5) Packets
LSA Types
The LSA Header
LSA Type 1: Router LSA
LSA Type 2: Network LSAs
LSA Type 3: Summary LSA and LSA Type 4: Summary LSA
LSA Type 5: Autonomous System External LSA
Shortest Path First Algorithm and Route Selection
What Is the Shortest Path First Algorithm?
Selection of the Best Route
OSPF LSA Propagation
Walk-Through of an LSA Through a Designated Router
The OSPF Decision Tree When Receiving an LSA
The ROUTER OSPF <PROCESS-ID> Command
The NETWORK Command and the Wildcard Mask
OSPF Selection of a Router ID
Trade-offs and the Loopback Address
The OSPF COST INTERFACE Command
The SHOW IP PROTOCOLS Command
The SHOW IP ROUTE Command
The SHOW IP OSPF INTERFACE Command
The SHOW IP OSPF Command
The SHOW IP OSPF NEIGHBOR Command
The SHOW IP OSPF NEIGHBOR DETAIL Command
The DEBUG IP OSPF ADJ Command

5 OSPF Operations in a Multiarea Network

Functional Descriptions of Routers in an OSPF Network
Internal Router
Area Border Router
Backbone Router
Autonomous System Boundary Router
Types of OSPF Link-State Advertisements
LSA Type 1: Router LSA
LSA Type 2: Network LSA
LSA Type 3: Network Summary LSA
LSA Type 5: External LSA
Other LSA Types
Differentiating Between External Type 1 and External Type 2 OSPF LSAs
Output of the SHOW IP OSPF DATABASE Command for LSA Types 1, 2, 3, and 5
Relating the OSPF LSA Types to IP Routing Table Entries
Types of OSPF Areas
Standard Area
Backbone Area
Stub Area
Totally Stubby Area
Requirements for a Stub and a Totally Stubby Area
LSA Propagation Across a Standard Area OSPF Network
LSA Propagation Across a Stub Area and Standard Area OSPF Network
LSA Propagation Across a Totally Stubby Area and Standard Area OSPF Network
Benefits of OSPF Summarization
The Effects of Addressing and Summarization in an OSPF Environment
The OSPF NETWORK Statement
Configuration Example of an Internal Router and an ABR
The OSPF STUB Command
The OSPF STUB Command with a NO-SUMMARY Modifier
The OSPF DEFAULT-COST Command
The OSPF ABR SUMMARIZATION Command
The OSPF ASBR SUMMARY-ADDRESS Command
OSPF Virtual Link
The SHOW IP OSPF DATABASE Command
The SHOW IP OSPF BORDER-ROUTERS Command
The SHOW IP OSPF VIRTUAL-LINKS Command
The SHOW IP OSPF <PROCESS-ID> Command

6 EIGRP Operations and Configuration

EIGRP and Its Major Features
Benefits of EIGRP in Comparison to Other IP Routing Protocols
EIGRP Terminology
Neighbor Table
Topology Table
Successor
Feasible Successor
Building EIGRP Neighbor Relationships
Behavior of Different Media Types
Frequency of EIGRP Neighbor Relationships by Media Type
Declaring a Neighbor Dead
The Default Hold Time
Forming Neighbor Relationships in EIGRP
EIGRP Packet Types
Hello Packets
Update Packets
Query Packets
Reply Packets
ACK Packets
The Neighbor Table
EIGRP Reliability
EIGRP and Packet Acknowledgment
Updating Retransmissions and Timeouts
Initial Exchange of Packets
EIGRP Route Selection and Metric Calculation
EIGRP Metric Calculation Formula
The DUAL Algorithm
Feasible Distance
Advertised Distance
Feasibility Condition
Loop Avoidance
The ROUTER EIGRP Command
The NETWORK Statement
Show IP Protocols Command
Show IP Route Command
SHOW IP EIGRP NEIGHBORS Command
SHOW IP EIGRP TOPOLOGY Command
SHOW IP EIGRP TRAFFIC Command
The SHOW IP EIGRP EVENTS Command
The SHOW IP EIGRP INTERFACE Command
The DEBUG EIGRP PACKET Command
The DEBUG EIGRP NEIGHBOR Command
The DEBUG EIGRP FSM Command

7 Advanced EIGRP Behavior and Configuration

Using the Proper Bandwidth for the WAN Interfaces
Good Addressing
Hierarchical Network Design
Sufficient Memory on the Router
Sufficient Bandwidth on WAN Interfaces to Handle Update Traffic
Limiting the Update and Query Range
Disabling Automatic Summarization
EIGRP Manual Summarization
The EIGRP Interface Command for Summarization
Benefits of the EIGRP Summarization Method
Examination of the IP Routing Table with EIGRP Summarization
Null0 Route Removal
EIGRP Load Balancing
Load Balancing with EIGRP
Maximum Number of Equal-Cost Routes in the Routing Table
Default Number of Equal-Cost Routes Allowed
Unequal-Cost Load Balancing with EIGRP
Considerations for Using VARIANCE
The VARIANCE Command
Using Bandwidth Statement
Default Bandwidth Setting for a Serial interface
NBMA Bandwidth Settings
Limiting the Percentage of Bandwidth EIGRP Uses
The IP BANDWIDTH-PERCENT EIGRP Command
Point-to-Point Subinterfaces with CIR Per Subinterface
Multipoint Circuit with Equal CIR Per Neighbor
Multipoint Circuit with Unequal CIR Per Neighbor (Not Recommended)
Multipoint Circuit with Unequal CIR Per Neighbor (Recommended)
Configuring Frame Relay
The EIGRP Query Process
The “Stuck in Active” State
EIGRP Query Range
Limiting the Scope of Updates and Query Propagation
How Summarization Can Help
How Filters Can Help
A Nonscalable EIGRP Network with Bad Addressing
A Scalable EIGRP Network with Good Addressing

8 BGP Basic Operations and Configuration

When It Is Appropriate to Use BGP
When an Autonomous System Is a Transit AS
When Multiple Exit Points and Traffic Must Be Manipulated
When the Effects of BGP Are Well Understood
When It Is Not Appropriate to Use BGP
A Single Entry/Exit Point to an Autonomous System
Routing Policy or Path Selection Manipulation Is Not Required
Lack of Memory or CPU Resources on BGP Routers
Limited Understanding of Route Filtering and BGP
Low Bandwidth Between Autonomous Systems
Static and Default Routes
Static and Default Route Commands
Redistribution of Default Routes and RIP
Redistribution of Default Routes and OSPF
What Is an Exterior Routing Protocol?
Border Gateway Protocol Version 4 and How It Differs from Its Predecessors
BGP Version 4 Compared With Version 3
Major RFCs for BGP
Packet Manipulation
BGP Uses Attributes to Make Policy decisions
The Hop-by-Hop (AS-by-AS) Routing Paradigm
An Autonomous System in Relation to BGP
How to Get an Official Autonomous System Number
The Internet and Routing
Over 70,000 Summarized Routes
30Megabyte Routing Table
BGP Terminology and Characteristics
Terminology
Characteristics
BGP Peering
What Are BGP Neighbors, BGP Speakers, and BGP Peers?
Internal BGP Neighbors
External BGP Neighbors
What Is a BGP Attribute?
Well Known vs. Optional
Mandatory vs. Discretionary
Transitive vs. Nontransitive
Partial vs. Complete
BGP Attributes
AS_PATH Type Code 2
NEXT_HOP Type Code 3
LOCAL_PREF Type Code 5
MULTI_EXIT_DISC Type Code 4
ORIGIN Type Code 1
COMMUNITY Type Code 8
WEIGHT (Proprietary to Cisco)
BGP Synchronization
What BGP Synchronization Does When It Is Turned On (Default Setting)
What Happens When BGP Synchronization Is Turned Off
When and Why Synchronization Might Be Disabled
BGP Message Types
HEADER
UPDATE
NOTIFICATION
KEEPALIVE
BGP Route Selection Process
The ROUTER BGP AUTONOMOUS-SYSTEM Command
The NETWORK Statement Under Router BGP
The NEIGHBOR Command
Internal or External Neighbors
BGP Basic Configuration
The NEIGHBOR NEXT-HOP-SELF Command
The NO SYNCHRONIZATION Command
The AGGREGATE ADDRESS Command
The CLEAR IP BGP Command
Purpose of CLEAR IP BGP
Why You Should Never Use the * Option
What Is Soft Reconfiguration?
What Is the Difference Between Soft Reconfiguration In and Out
BGP Configuration
The SHOW IP PROTOCOLS Command
The SHOW IP ROUTE Command
The SHOW IP BGP NEIGHBORS Command
The SHOW IP BGP Command
The SHOW IP BGP SUMMARY Command
The DEBUG IP BGP UPDATES Command

9 BGP Scalability Issues

Peering with iBGP Neighbors
Contrasting iBGP Behavior to an IGP Method of Propagating Changes
Scalability Issues with iBGP Neighbors
Route Reflectors as a Scalability Solution
The Purpose of Route Reflectors
The Benefits of Route Reflectors
Route Reflector Terminology
Route Reflector
Route Reflector Client
Route Reflector Cluster
Nonclient Peer
Originator ID
Cluster ID
Cluster List
Route Reflector Design and Migration Tips
Route Reflector Operations
Route Reflector Configuration
The Route-Reflector-Client Configuration Option
The BGP CLUSTER-ID <X> command
Configuration Using Redundant Route Reflectors
Verifying Route Reflectors
Defining Prefix Lists
Benefits of Prefix Lists
Increased Performance
Incremental Updates
A User-Friendly Command-Line Interface
Prefix List Operations
Configuring Prefix Lists
IP PREFIX-LIST
NEIGHBOR X.X.X.X PREFIX-LIST
Prefix List Sequence Numbering
Prefix List Example
Verifying Prefix Lists
The SHOW IP PREFIX-LIST Command
The CLEAR IP PREFIX-LIST Command
Types of Multihoming
Default Routes from All Providers
Benefits of Using Default Routes Alone
Disadvantages of Using Default Routes Alone
Example of Default Routes Alone for Multihoming
Limited BGP Table and Default Route from Each Provider
Benefits of Receiving a Limited BGP Table
Drawbacks of Using Limited BGP Table
Example of Receiving a Limited BGP Table
Full BGP Table from All Providers
Benefits of Receiving the Full BGP Table
Drawbacks of Receiving the Full BGP Table
Example of Receiving the Full BGP Table
BGP Metric Commands
The NEIGHBOR X.X.X.X WEIGHT <VALUE> Command
The BGP DEFAULT LOCAL-PREFERENCE <VALUE> Command
A Multihoming BGP Configuration Example
Notifying BGP of Which Networks to Advertise
The NETWORK Command
Redistribution of Static Routes
Redistribution of Dynamic Routing Protocols
Learned from Another BGP Speaker
Using the NETWORK Command
Redistributing Static Routes into BGP
Redistributing Dynamic Routing Protocols into BGP
Redistribution of BGP into a Local Routing Protocol
ISP Policy on Redistribution
End Autonomous Systems Policy on Redistribution

10 Route Filtering and Redistribution

When to Use Redistribution
Defining Redistribution
Redistribution Considerations
Selecting the Best Routing Protocol
Administrative Distance
Seed Metric
Automatic Redistribution
Hierarchical Routing Protocols
Selecting the Core and Edge Routing Protocols
Defining the Core Routing Protocol
Defining the Edge Routing Protocol
Redistributing the Edge Routing Protocol and Sending a Default Route
Mutually Redistributing the Routing Protocol and Preventing Routing Loops
Mutually Redistributing Protocols and Preventing Routing Loops
Configuring Redistribution into RIP
Configuring Redistribution into OSPF
Configuring Redistribution into EIGRP
EIGRP and OSPF Redistribution Example
Configuring the DEFAULT-METRIC Command
Configuring the PASSIVE-INTERFACE Command
Configuring Static Routes
Static Route Example
Configuring a Default Route and the DEFAULT-NETWORK Command
Configuring a Redistribution Using the IP DEFAULT-NETWORK Command
Resolving Path Selection Problems Resulting from Redistribution
Solutions for Path Selection Problems
Filters
Administrative Distance Control
Using Route Filtering
Configuring Route Filtering
Basic Example of Route Filtering
Using Administrative Distance
Configuring Administrative Distance Control
Complex Example of Administrative Distance Control
The SHOW IP ROUTE Command
The TRACEROUTE Command

11 Policy-Based Routing and Route Maps

Defining Policy-Based Routing
Reasons to Use Policy-Based Routing
Types of Policy-Based Routing
Queuing
Filtering
Path Manipulation
Defining Route Maps
MATCH and SET function
Sequence Number
Comparison Between Route Maps and Access Lists
Creating a Route-Map Command
ROUTE-MAP MAP-TAG {PERMIT|DENY} [SEQUENCE-NUMBER]
MATCH {CONDITION}
SET {ACTION}
Linking a Route Map to an Interface
IP POLICY ROUTE-MAP
IP ROUTE-CACHE POLICY
Conclusion
The SHOW IP POLICY Command
The SHOW ROUTE-MAP Command