Foundation Summary


The "Foundation Summary" section of each chapter lists the most important facts from the chapter. Although this section does not list every fact from the chapter that will be on your exam, a well-prepared candidate should, at a minimum, know all the details in each "Foundation Summary" before going to take the exam.

The three layers of a hierarchy are as follows :

  • The access layer

  • The distribution layer

  • The core layer

Queuing techniques that are manually configured with access lists are as follows:

  • Priority queuing

  • Custom queuing

  • Class-based weighted fair queuing (CBWFQ)

  • Low-latency queuing (LLQ)

Table 3-4 outlines the IP address ranges reserved for private addressing, as specified in RFC 1918.

Table 3-4. Private Address Ranges

Address Range

Prefix Mask

Number of Classful Addresses Provided to


1 Class A to


16 Class Bs to


256 Class Cs

To translate one network address into another, the process must differentiate between the functionality of the addresses being translated. Table 3-5 lists the categories of functions.

Table 3-5. Categories of Functions



Inside Global

These are the addresses that connect your organization indirectly to the Internet. Typically, these are the addresses provided by the ISP. These addresses are propagated outside the organization. They are globally unique and are the addresses used by the outside world to connect to inside the organization. Simply explained, they are the addresses that define how the inside addresses are seen globally by the outside.

Inside Local

These are the addresses that allow every end device in the organization to communicate. Although these addresses are unique within the organization, they are probably not globally unique. They may well be private addresses that conform to RFC 1918. They are the inside addresses as seen locally within the organization.

Outside Global

These are the Internet addresses (all the addresses outside the domain of the organization). They are the outside addresses as they appear to the global Internet.

Outside Local

These addresses are external to the organization. This is the destination address used by a host inside the organization connecting to the outside world. This will be the destination address of the packet propagated by the internal host. This is how the outside world is seen locally from inside the organization.

Figure 3-8 illustrates the use of NAT terms.

Figure 3-8. Using the NAT Terms


IPv6 provides the following features to allow IP networks to scale in a way that IPv4 could not:

  • 128-bit address The increased address space is a fundamental feature of IPv6. The address has been increased from 32 bits in IPv4 to 128 bits in IPv6.

  • The new header The new format increases efficiency in routing. The 64-bit alignment of the fields means the packets are processed at higher speeds. Unnecessary fields have been removed, further streamlining the routing process. A new extension header has been added for optional fields.

  • Autoconfiguration This eliminates the need for DHCP servers and manual IP addressing, thus easing network administration and reducing the volume of network errors due to misconfiguration. Not only is end system address acquisition automated, but it also allows for the network to be renumbered or readdressed without visiting each end system for reconfiguration.

  • Security and mobility These are built into the protocol specification, as opposed to being configurable options. Both security and mobility are enhanced by the ability to have end-to-end connectivity because of the greater address space available.

  • Transitioning from an IPv4 network Transitioning an organization is still complex, requiring much consideration. However, transitioning schemes have been carefully thought through and integrated into the protocol functionality. Two of the most common methods include:

    - Dual stack

    - 6to4 or manually configured tunneling

IPv6 offers the following benefits and features:

  • Larger address space, allowing for a larger number of systems that can be globally addressed and a more scalable network

  • Increased address space, allowing for a deeper hierarchical structure

  • Simplified header, allowing for greater routing efficiency and thus network performance

  • Policies for network architecture flexibility, allowing evolution and growth of the protocol

  • Support for routing and route aggregation

  • Simple administration through serverless autoconfiguration, the ability to renumber with ease, and multihoming, all of which allow a level of plug-and-play support

  • Security using IP Security (IPSec) support for all IPv6 devices

  • Support for Mobile IP and mobile computing devices (direct- path )

  • Multicast support built into the protocol using a greater number of addresses and efficient mechanisms

CCNP BSCI Exam Certification Guide
CCNP BSCI Exam Certification Guide (CCNP Self-Study, 642-801) (3rd Edition)
ISBN: 1587200856
EAN: 2147483647
Year: 2002
Pages: 194
Authors: Clare Gough © 2008-2017.
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