Chapter 2: LAN Segmentation


CCDA Exam Topics Covered in This Chapter:

  • Given a network design or a set of requirements evaluate a solution to incorporate equipment and technology within a Campus design.

Layer 2 (L2) switching is the process of using the hardware address of devices on a LAN to segment a network. When Cisco discusses switching, they’re talking about Layer 2 switching unless they say otherwise. However, Cisco also performs Layer 3 (L3) switching, which really means routing, but through a device with more options than a basic router can perform.

Switches truly have changed the way networks are designed and implemented. If a pure switched design is properly implemented, the result is a clean, cost-effective, and resilient internetwork. Routing protocols have processes for stopping network loops from occurring at the Network layer. However, if you have redundant physical links between your switches, routing protocols won’t do a thing to stop loops from occurring at the Data Link layer. That’s exactly the reason the Spanning-Tree Protocol (STP) was developed—to put a stop to loops in a Layer 2 switched internetwork.

In contrast to the networks of yesterday that were based on collapsed backbones, today’s network design is characterized by a flatter architecture— thanks to switches. So now what? How do you break up broadcast domains in a pure switched internetwork? By creating virtual LANs (VLANs), that’s how!

This chapter delves into the nitty-gritty of both Layer 2 and Layer 3 switching; it surveys and compares network design before and after switching technologies were introduced. It also discusses the essentials of the Spanning- Tree Protocol and explores how it works within a switched network. The remaining topics in this chapter are VLANs, frame tagging, and Ethernet networking. But first, let’s discuss the advantages and disadvantages of using a bridge, router, or LAN switch to segment a network.




CCDA. Cisco Certified Design Associate Study Guide
CCDA: Cisco Certified Design Associate Study Guide, 2nd Edition (640-861)
ISBN: 0782142001
EAN: 2147483647
Year: 2002
Pages: 201

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