High Availability Networking
with Cisco
Vincent C. Jones
Table of Contents (Detailed)
Front Matter
Acknowledgments
Preface
1. Reliability Theory.
Defining Network Availability
Determining Availability Requirements
Availability Measurement and Reporting
Mathematics of Reliability and Availability.
MTBF and MTTR
Improving Availability through Higher Reliability
Improving Availability through Redundancy
Need for Testing
Functional Availability
Network Vulnerabilities.
Classical Hardware Considerations
Software Considerations
Site Infrastructure
Communications Links
Security
Designing for Improved Network Availability.
WAN Communications Diversity
Internal Diversity
2. Bridging and Routing.
Connectivity in the OSI Reference Model
Network Topologies
Multiple Connections versus Single Connections
Detecting Failure
Bridging for Higher Availability.
Classic Bridging
Token Ring Source Route Bridging
Transparent Spanning-Tree Bridging
Switched LAN Design
Routing for Higher Availability.
Routing Fundamentals
Static Routing
RIP Routing
OSPF Routing
EIGRP Routing
Integrated IS-IS Routing
BGP Routing
Routed Network Design
3. Multihomed Hosts.
Impact of Network Connection Failure
Application Recovery Requirements
Two Network Interfaces with One IP Address.
Smart Network Interface Cards
Anatomy of a Novell Server
Configuration Example: Generic UNIX using routed
Configuration Example: Practical Linux Server using GateD
Two Systems with One IP Address.
Server Clusters
Server Cluster Considerations
Server Farms
Intelligent Clients
4. Dial Backup for Permanent Links.
Getting Adequate Bandwidth on Demand
Coping with Backup Bandwidth Limitations
The Need for Constant Testing
Dial Backup Approaches.
Dialing Driven by Interface Status Down (Cisco Backup Interface)
Dialing Driven by Routing Table Entry Missing (Cisco Dialer Watch)
Dialing Driven by Best Route to Destination (Dial-on-Demand)
Choosing a Dial Backup Approach
Basic ISDN Dial Backup.
Configuration Example: Dial Backup Using Cisco Backup Interface
Configuration Example: Cisco Backup Interface Options
Configuration Example: Dial Backup Using Dialer Watch
Configuration Example: Dial Backup Using Dial-on-Demand
5. Advanced Dial Backup.
General Difference Between POTS and ISDN
Cisco Implementation Considerations
Configuration Example: External Modem on the AUX Port to a PRI with Digital Modems
Combining Channel for Higher Bandwidth.
Multilink PPP
Configuration Example: Multilink PPP with Asynchronous Modems
Configuration Example: BRI to BRI Multilink PPP
Load Sharing of Equal Cost Links
Configuration Example: 2.5 Mbps ISDN Dial Backup
Supporting IPX along with IP.
Configuration Example: IPX Dial Backup with IPXRIP
Configuration Example: Dial Backup with OSPF for IP and IPXRIP for IPX
BGP-Driven Dial Backup.
Configuration Example: Dial Backup for Dial Backup (IP and IPX)
Configuration Example: Dial Backup for Multiple Primary Links
6. Multiple Routers at a Single Site.
Passive RIP
Configuration Example: Passive RIP
Proxy ARP
IRDP, BootP, and DHCP
VRRP and Cisco HSRP
Configuration Example: Simple HSRP
Configuration Example: Load Balancing with HSRP
Configuration Example: Meeting Special Needs with HSRP
Dial Backup by One Router for a Line on Another.
Configuration Example: Using Dialer Watch
Configuration Example: Using Dial-on-Demand
Configuration Example: Using BGP-Driven Dial-on-Demand
Protecting against LAN Segmentation.
A Workaround for IP Networks
Configuration Example: Single LAN with Two WAN Routers
Configuration Example: Putting It All Together
7. Hub and Spokes Topology.
Routing Requirements for Hub Routers versus Spoke Routers
Configuration Example: EIGRP Everywhere
Configuration Example: OSPF Hub with RIPv2 Spokes
Configuration Example: Dual Connections to Every Spoke
Dial Backup with Multiple Dial Access Servers.
Eliminating Dial Access Server Dependency
Configuration Example: Single Spoke, Two Core Targets, IP Only
Configuration Example: Single Spoke, Two Core Targets, IP and IPX
Configuration Example: Multiple ISDN and Async Targets
Using More than One Hub.
Dealing with Loss of Hub Network Connectivity
Configuration Example: Hub Dialing Around Loss of Hub Internal Connectivity
8. Connecting to Service Providers.
Configuration Example: Redundant Static Routes
Configuration Example: Static Routes Driven by an IGP
Configuration Example: Primary Path with Dial Backup
Configuration Example: Using NAT to Route Return Traffic
Connecting to an Internet Service Provider.
Challenges for Higher Internet Availability
Configuration Example: Static Routing with Two Internet Links
Routing with BGP
Configuration Example: Using BGP for Link Fault Detection
Configuration Example: BGP to ISP with Dynamic Internal Routing
Configuration Example: Detecting ISP Failures with BGP
Connecting through Multiple Internet Service Providers.
Configuration Example: Using NAT for an Alternate ISP Path
Interdomain Routing with BGP
Configuration Example: Multihomed Organization Speaking BGP
Configuration Example: Multihomed BGP with Redundant Routers
9. Connecting through Firewalls.
How Firewalls Are Used
State Sensitive versus Stateless Firewalls
Router Mode versus End-System Mode Firewalls
Firewalls in a Fully Redundant Network.
Configuration Example: Redundant Network with Firewalls
Automating Failover in Redundant Firewall Networks.
Router Controlled Failover Using Mirrored Router Mode Firewalls
Configuration Example: Automatic Failover with Router Mode Firewalls
Router Controlled Failover of Alternate End-System Mode Firewalls
Configuration Example: Automatic Failover with End-System Mode Firewalls
10. IBM Mainframe Connections.
How DLSw Works
Configuration Example: Redundant DLSw between Token Rings
DLSw for Ethernet Attached Devices.
Redundant DLSw versus Transparent Bridging
Redundant DLSw without Source Route Bridging
Configuration Example: Redundant Ethernet Peers using Backup Peers
Configuration Example: Backup Peers on a Segmentable LAN
Configuration Example: Redundant Peers using DLSw+ Ethernet Redundancy
DLSw through Firewalls.
DLSw Backup Peers for Firewall Redundancy
Configuration Example: Token Ring DLSw through Dual NAT Firewalls
Configuration Example: Ethernet DLSw through Dual NAT Firewalls
11. Disaster Recovery Considerations.
Disaster Recovery Planning
Disaster Recovery Approaches
Traditional Approaches.
Hot Backup Facility Approaches.
One IP Address for Two Sites
Configuration Example: Backup Server and Network Address Translation
Configuration Example: Backup Server using NAT and Host Routing
Domain Name System Operation
Domain Name System Redirection
Load Sharing Approaches.
Load Sharing Using Domain Name System Redirection
HTTP Redirection
12. Management Considerations.
Network Management with SNMP
Monitoring Functions that Do Not Report Status
Security
Routine Testing of Backup Facilities
Configuration Management.
Configuration Documentation Matches Reality
Configuration is Understood
Managing Configuration Changes
Recovering from Emergency Repair Efforts
Total Quality Control.
Design Verification
Error Analysis
Glossary
Index
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