Cisco Catalyst QoS: Quality of Service in Campus Networks

378 Chapter 10: End-to-End QoS Case Studies

Chapter Prerequisites and Material Presentation

This chapter assumes the reader has read through all the material in the previous chapters

and grasps the basic understanding of all the QoS fundamentals presented in earlier

chapters. This chapter presents material from an overview perspective. The chapter does not

discuss command-line parameters or configuration specifics. Instead, this chapter presents

a sample configuration and then discusses it. The reader should know how to relate the QoS

configuration discussions to the sample configurations. The end goal of the chapter is to

give the reader an understanding and overview of an end-to-end QoS design and topology.

Furthermore, this chapter refers to applications such as file sharing and databases. In many

examples, access-control lists (ACLs) define these applications using TCP and UDP port

assignments. The ACLs in the examples are not true representations of the necessary ACLs

to profile the applications. Instead, the examples include the ACLs for completeness of the

command-line interface (CLI) syntax.

The material presented in this chapter begins with the access layer and moves to the core.

Because the classification begins in the access layer, the explanations begin there as well.

To facilitate an easier understanding of the sample configuration presented, the configura-

tions do not illustrate repeated identical interface configurations or infrastructure-related

materials, such as spanning-tree parameters, IP routing protocols, and VLAN databases.

Multiplatform Campus Network Design and Topology

Figure 10-1 shows the campus network topology this chapter uses for sample configura-

tions. The principle of the campus network design is to apply QoS features to support

multiple classes of service among different classes of users and applications. To illustrate a

sample campus network topology, the campus network design mimics a university campus

consisting of multiple buildings. Each building uses two distribution layer switches to

aggregate access layer switches that connect individual workstations and IP Phones in

multiple wiring closets per floor of each building. The core aggregates each building by

interconnecting the distribution layer switches. In addition to providing aggregation, the

core also offers redundant Internet connectivity with firewall filtering, virtual private

networking (VPN) services, and IP connectivity to iSCSI routers that interconnect a Cisco

Multilayer Director and Fabric Switches (MDS) Fibre Channel storage-area network

(SAN). A core server farm supplies global enterprise services such as e-mail, file storage,

web services, and applications.

In the core, one of the Catalyst 6500 switches uses Native IOS Software; the other Catalyst

6500 switch uses Hybrid Software. Chapter 8, “QoS Support on the Catalyst 6500,”

discusses the differences between Native and Hybrid Software. The topology uses different

software for illustration purposes; most campus designs keep the software versions

consistent.

Multiplatform Campus Network Design and Topology 379

Figure 10-1 Sample Multiplatform Campus Network Topology

Catalyst 4507R and 3550-12G switches create the distribution layer. The distribution layer

aggregates access layer switches in buildings throughout the campus network. These

switches also connect regional server farms for the purpose of providing services on a per-

building basis. Such services include web caching, authentication, and file services. The

distribution layer uses Layer 3 connections to the core with Layer 2 connections to the

access layer. As a result, the distribution layer switches route between local IP subnets. The

core switches advertise default routes to the distribution layer so that the distribution layer

can route to other IP subnets residing in other buildings. It is not necessary for the distri-

bution layer to contain all the campus routes in its routing table.

L2

L2

ManagementEngineering

Workstations

Cisco IP

Phones

Faculty Students

Workstations

Cisco IP

Phones

L3

L3

L2

L3

L2

L3 Port Channel

L2

Catalyst 6500 Sup1/

MSFC (Hybrid Software)

Catalyst 4507R

with Supervisor

IV

Catalyst 4508

Catalyst 6500 Sup2/MSFC

II (Native Software)

Catalyst 3550-12G

Catalyst 2950G-24

Gig 1/1

Gig 1/2

Gig 5/1

Gig 5/2

Regional

Server

Farm

Regional

Server

Farm

Internet Connection 1 Internet Connection 2

Cisco MDS SAN

Storage Area

Server

Farm

Ser 4/0/0 Ser 4/0/0

Gig 3/4

Gig 3/3

Gig 3/1

Gig 3/2

Gig 7/2

Gig 7/1

Gig 3/3

Gig 3/4

Gig 3/1

Gig 3/2

Gig 7/1

Gig 7/2