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Chapter 1

The Campus Network

Distribution Layer Switches

As discussed earlier, the primary function of the distribution layer is to pro-
vide routing, filtering, and WAN access and to determine how packets can
access the core, if needed.

Distribution layer switches are the aggregation point for multiple access

switches and must be capable of handling large amounts of traffic from these
access layer devices. The distribution layer switches must also be able to
participate in multi-layer switching (MLS) and be able to handle a route
processor.

The Cisco switches that provide these functions are as follows:

2926G A robust switch that uses an external router processor like a
4000 or 7000 series router.

5000/5500 The most effective distribution layer switch, it can support
a large amount of connections and also an internal route processor mod-
ule called a Route Switch Module (RSM). It can switch process up to
176KBps.

6000 The Catalyst 6000 can provide up to 384 10/100 Ethernet connec-
tions, 192 100FX FastEthernet connections, and 130 Gigabit Ethernet ports.

Core Layer Switches

The core layer must be efficient and do nothing to slow down packets as they
traverse the backbone. The following switches are recommended for use in
the core:

5000/5500 The 5000 is a great distribution layer switch, and the 5500
is a great core layer switch. The Catalyst 5000 series of switches includes
the 5000, 5002, 5500, 5505, and 5509. All of the 5000 series switches use
the same cards and modules, which makes them cost effective and pro-
vides protection for your investment.

6500 The Catalyst 6500 series switches are designed to address the need
for gigabit port density, high availability, and multi-layer switching for
the core layer backbone and server-aggregation environments. These
switches use the Cisco IOS to utilize the high speeds of the ASICs, which
allows the delivery of wire-speed traffic management services end to end.

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