Introduction | p. xvi |
Understanding, Configuring, and Troubleshooting CEF | p. 3 |
Introduction to Packet-Switching Architectures | p. 5 |
Routing and Switching | p. 5 |
Understanding Broadcast and Collision Domains | p. 5 |
Broadcast and Collision Domains | p. 6 |
Broadcast and Collision Domains in Routing | p. 7 |
Layer 3 Switching | p. 8 |
Understanding Router Pieces and Parts | p. 9 |
Interface Processors | p. 10 |
Central Processing Unit | p. 11 |
Memory | p. 11 |
Backplanes and Switching Fabrics | p. 11 |
Shared Memory | p. 11 |
Crossbar Switching Fabric | p. 13 |
Bus Backplanes | p. 14 |
Cisco IOS Software: The Brains | p. 17 |
Memory Management | p. 17 |
Memory Pools | p. 17 |
Memory Regions | p. 18 |
Packet Buffers | p. 20 |
Interaction with Interface Processors | p. 28 |
Processes and Scheduling | p. 28 |
Process Memory | p. 28 |
Process Scheduling | p. 29 |
Understanding the Scheduler | p. 29 |
Process Life Cycle | p. 29 |
Process Priorities | p. 32 |
Scheduling Processes | p. 32 |
Process Watchdog | p. 34 |
Special Processes | p. 35 |
Putting the Pieces Together: Switching a Packet | p. 35 |
Getting the Packet off the Network Media | p. 35 |
Inbound Packets on Shared Media Platforms | p. 36 |
Inbound Packets on Centralized Switching Routers with Line Cards | p. 37 |
Inbound Packet Handling on Distributed Switching Platforms | p. 38 |
Switching the Packet | p. 39 |
Switching the Packet Quickly During the Receive Interrupt | p. 39 |
Process-Switching the Packet | p. 41 |
Transmitting the Packet | p. 44 |
Hardware and Software show Commands | p. 45 |
Summary | p. 48 |
Understanding Cisco Express Forwarding | p. 51 |
Evolving Packet-Switching Methods | p. 51 |
Process Switching | p. 51 |
Fast Switching | p. 52 |
What Is CEF? | p. 53 |
CEF Tables | p. 54 |
Forwarding Information Base (FIB) | p. 54 |
The Adjacency Table | p. 60 |
Relating the CEF Tables | p. 61 |
CEF Table Entries | p. 62 |
FIB Entries | p. 62 |
Attached FIB Entry | p. 63 |
Connected FIB Entry | p. 63 |
Rcceive FIB Entry | p. 63 |
Recursive FIB Entry | p. 64 |
Default Route Handler FIB Entry | p. 66 |
ADJFIB FIB Entry | p. 66 |
Learned from IGPs | p. 67 |
Generic FIB Entries | p. 67 |
Interface-Specific FIB Entries | p. 68 |
FIB Entries Built for a Multiaccess Network Interface | p. 68 |
FIB Entries Built on a Point-to-Point Network Interface | p. 69 |
FIB Entries Built on a 31-Bit Prefix Network Interface | p. 69 |
Special Adjacencies | p. 69 |
Auto Adjacencies | p. 70 |
Punt Adjacency | p. 70 |
Glean Adjacency | p. 71 |
Drop Adjacency | p. 72 |
Discard Adjacency | p. 73 |
Null Adjacency | p. 73 |
No Route Adjacencies | p. 74 |
Cached and Uncached Adjacencies | p. 74 |
Unresolved Adjacency | p. 75 |
Switching a Packet with CEF | p. 75 |
The CEF Epoch | p. 77 |
Configuring CEF/dCEF | p. 77 |
Summary | p. 78 |
References | p. 79 |
CEF Enhanced Scalability | p. 81 |
Fundamental Changes to CEF for CSSR | p. 82 |
Data Structures | p. 82 |
Switching Path Changes | p. 84 |
Changes to show Commands | p. 86 |
Show ip cef | p. 86 |
Show ip cef interface | p. 86 |
Show ip cef summary | p. 87 |
Show cef state capabilities | p. 88 |
New show ip cef Commands | p. 89 |
Show ip cef tree | p. 89 |
Show ip cef internal | p. 90 |
Show ip cef switching statistics | p. 91 |
New show cef Commands | p. 91 |
CEF Event Logger | p. 94 |
CEF Consistency Checker | p. 97 |
Passive Checkers | p. 97 |
Active Checkers | p. 97 |
Consistency-Checking Process | p. 98 |
New CEF Processes | p. 100 |
FIB Manager | p. 100 |
Adjacency Manager | p. 100 |
Update Manager | p. 100 |
Summary | p. 101 |
Basic IP Connectivity and CEF Troubleshooting | p. 103 |
Troubleshooting IP Connectivity | p. 103 |
Accurately Describe the Problem | p. 104 |
Scoping the Network Topology | p. 105 |
Reviewing the OSI Model for Troubleshooting | p. 106 |
Troubleshooting Physical Connectivity | p. 106 |
Troubleshooting Layer 2 Issues | p. 107 |
Verifying the ARP Table | p. 108 |
Verifying the Routing Table | p. 111 |
Using IOS Ping with the Record Option to Rule Out CEF | p. 115 |
Troubleshooting the CEF FIB Table | p. 116 |
Verifying the CEF Configuration | p. 117 |
Confirming the IP CEF Switching Path | p. 119 |
Using CEF Accounting Counters to Confirm the Switching Path | p. 123 |
Verifying the CEF Switching Details | p. 123 |
Verifying the Adjacency Table | p. 126 |
Hardware-Specific Troubleshooting | p. 128 |
Troubleshooting Punt Adjacencies | p. 129 |
Understanding CEF Error Messages | p. 131 |
Troubleshooting Commands Reference | p. 131 |
Summary | p. 133 |
References | p. 133 |
CEF Case Studies | p. 135 |
Understanding Packet Switching on the Cisco Catalyst 6500 Supervisor 720 | p. 137 |
CEF Switching Architecture on the Cisco Catalyst 6500 | p. 137 |
Understanding Software-Based CEF and Hardware-Based CEF | p. 137 |
Centralized and Distributed Switching | p. 138 |
Troubleshooting CEF on the Catalyst 6500 SUP720 Platforms | p. 139 |
Simple Checking of Connectivity | p. 139 |
Systematic Checking of Connectivity | p. 141 |
Troubleshooting Load Sharing | p. 148 |
Summary | p. 149 |
References | p. 149 |
Load Sharing with CEF | p. 153 |
Benefits of Load Sharing | p. 153 |
Load Sharing with Process Switching and Fast Switching | p. 154 |
Comparing CEF Per-Packet and CEF Per-Destination Load Sharing | p. 158 |
Understanding Per-Destination Load Sharing | p. 158 |
Understanding Per-Packet Load Sharing | p. 159 |
Minimizing Out-of-Order Packets | p. 159 |
Configuring CEF Per-Packet Load Sharing | p. 160 |
CEF Architecture and Load Sharing | p. 161 |
CEF Load Sharing Across Parallel Paths | p. 163 |
CEF Per-Destination Example | p. 163 |
CEF Per-Packet Example | p. 170 |
Per-Packet Load Sharing on Hardware-Based Platforms | p. 174 |
CEF Per-Packet Load Sharing on the Cisco GSR Platform | p. 175 |
CEF Load-Sharing Troubleshooting Examples | p. 176 |
CEF Per-Destination Load Sharing Overloading One Link | p. 176 |
CEF Per-Packet Load Sharing Causing Performance Issues | p. 188 |
Troubleshooting a Single-Path Failure with CEF Load Sharing | p. 190 |
CEF Traffic-Share Allocation | p. 192 |
CEF Polarization and Load-Sharing Algorithms | p. 200 |
Original Algorithm | p. 202 |
Universal Algorithm | p. 202 |
Tunnel Algorithm | p. 203 |
Hardware Platform Implementations | p. 203 |
Summary | p. 204 |
References | p. 205 |
Understanding CEF in an MPLS VPN Environment | p. 207 |
An Internet Service Provider's Simple MPLS VPN Design | p. 207 |
Understanding the CEF and MPLS VPN Relationship | p. 209 |
Label Disposition | p. 211 |
Label Imposition | p. 212 |
Label Swapping | p. 214 |
Troubleshooting an MPLS VPN | p. 214 |
CEF Considerations When Troubleshooting MPLS VPN Across Various Platforms | p. 215 |
Cisco 7200 Router with an NPE-G2 | p. 216 |
Cisco 7500 Router | p. 216 |
Cisco Catalyst 6500 with a Supervisor 2 | p. 217 |
Catalyst 6500 with a Supervisor 720 3BXL | p. 218 |
Cisco 12000 Series Router | p. 221 |
Cisco 10000 Series Router | p. 226 |
CEF and MPLS VPN Load-Sharing Considerations | p. 227 |
PE-CE Load Sharing: CE Multihomed to Same PE | p. 227 |
PE-CE Load Sharing: Site Multihomed to Different PEs | p. 233 |
Load Sharing Between P and P Devices | p. 242 |
CEF and MPLS VPN Load-Sharing Platform Dependencies | p. 243 |
Summary | p. 243 |
References | p. 244 |
Appendix | p. 247 |
Scalability | p. 249 |
Index | p. 255 |
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