Foundation Summary


The Foundation Summary is a collection of tables and figures that provides a convenient review of many key concepts in this chapter. If you are already comfortable with the topics in this chapter, this summary might help you recall a few details. If you just read this chapter, this review should help solidify some key facts. If you are doing your final preparation before the exam, the following tables and figures are a convenient way to review the day before the exam.

Table 1-4. Layers of Data Communications

OSI Layer

Protocol Data Unit

Mechanism to Process PDU

7 (application)

  

6 (presentation)

  

5 (session)

  

4 (transport)

TCP segment

TCP port

3 (network)

Packet

Router

2 (data link)

Frame

Switch/bridge

1 (physical)

  


Table 1-5. Types of Network Services

Service Type

Location of Service

Extent of Traffic Flow

Local

Same segment/VLAN as user

Access layer only

Remote

Different segment/VLAN as user

Access to distribution layers

Enterprise

Central to all campus users

Access to distribution to core layers


Table 1-6. Comparison of Hierarchical Layers

Layer

Attributes

Access

High port density to connect to end users, low cost, uplinks to higher layers of the campus network, and Layer 2 services (traffic filtering, VLAN membership, and basic QoS)

Distribution

Aggregation of access-layer devices, high Layer 3 throughput, QoS features, security- and policy-based functions, and scalable and resilient high-speed links into the core and access layers

Core

Fast data transport, no "expensive" Layer 3 processing, redundancy and resiliency for high availability, and advanced QoS




CCNP Self-Study(c) CCNP BCMSN Exam Certification Guide
Red Hat Fedora 5 Unleashed
ISBN: N/A
EAN: 2147483647
Year: 2003
Pages: 177

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