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This chapter is from the book

Foundation Summary

This section lists additional details and facts to round out the coverage of the topics in this chapter. Unlike most of the Cisco Press Exam Certification Guides, this “Foundation Summary” does not repeat information presented in the “Foundation Topics” section of the chapter. Please take the time to read and study the details in the “Foundation Topics” section of the chapter, as well as review items noted with a Key Topic icon.

Table 6-6 lists the protocols mentioned in or pertinent to this chapter and their respective standards documents.

Table 6-6 Protocols and Standards for Chapter 6


Standardized In

Address Resolution Protocol (ARP)

RFC 826

IPv6 Neighbor Discovery

RFC 4861, RFC 5942

Differentiated Services Code Point (DSCP)

RFC 2474

Table 6-7 lists some of the key IOS commands related to the topics in this chapter. (The command syntax for switch commands was taken from the Catalyst 3560 Multilayer Switch Command Reference, 15.0(2)SE. Router-specific commands were taken from the IOS Release 15 mainline Command Reference.)

Table 6-7 Command Reference for Chapter 6



show ip arp

EXEC command that displays the contents of the IP ARP cache.

show ipv6 neighbors

EXEC command that displays the contents of the IPv6 neighbor cache.

[no] switchport

Switch interface subcommand that toggles an interface between a Layer 2 switched function (switchport) and a routed port (no switchport).

[no] ip route-cache cef

Interface subcommand that enables or disables CEF switching on an interface.

[no] ip cef

Global configuration command to enable (or disable) CEF on all interfaces.

[no] ipv6 cef

Global configuration command to enable (or disable) CEF for IPv6 on all interfaces. For IPv6 CEF to be activated, ip cef must also be present.

[no] ip routing

Enables IP routing; defaults to no ip routing and no ipv6 unicast-routing on a multilayer switch.

[no] ipv6 unicast-routing

ip policy route-map map-tag

Router interface subcommand that enables policy routing for the packets entering the interface.

ipv6 policy route-map map-tag

Refer to Table 6-4 for the list of set commands related to policy routing.

Memory Builders

The CCIE Routing and Switching written exam, like all Cisco CCIE written exams, covers a fairly broad set of topics. This section provides some basic tools to help you exercise your memory about some of the broader topics covered in this chapter.

Fill In Key Tables from Memory

Appendix E, “Key Tables for CCIE Study,” on the CD in the back of this book, contains empty sets of some of the key summary tables in each chapter. Print Appendix E, refer to this chapter’s tables in it, and fill in the tables from memory. Refer to Appendix F, “Solutions for Key Tables for CCIE Study,” on the CD to check your answers.


Next, take a few moments to write down the definitions for the following terms:

  • policy routing
  • process switching
  • CEF
  • polarization
  • MLS
  • ARP
  • Proxy ARP
  • routed interface
  • fast switching
  • TTL
  • RIB
  • FIB
  • adjacency table
  • control plane
  • switched interface
  • data plane
  • IP routing
  • IP forwarding

Refer to the glossary to check your answers.

Further Reading

For a great overview of router switching paths, refer to www.cisco.com/en/US/tech/tk827/tk831/technologies_white_paper09186a00800a62d9.shtml.

For a good reference on load balancing with CEF, refer to http://cisco.com/en/US/tech/tk827/tk831/technologies_tech_note09186a0080094806.shtml.

Details on implementing and troubleshooting static routing can be found in numerous documents on the Cisco website. Recommended documents include “Specifying a Next Hop IP Address for Static Routes” (Document ID 27082), “Route Selection in Cisco Routers” (Document ID 8651), and “IOS Configuration Guide,” in particular, the “IP Routing: Protocol-Independent Configuration Guide” section.

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