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
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.
L3 Port Channel
Catalyst 6500 Sup1/
MSFC (Hybrid Software)
Catalyst 6500 Sup2/MSFC
II (Native Software)
Internet Connection 1 Internet Connection 2
Cisco MDS SAN
Ser 4/0/0 Ser 4/0/0