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Identifying the Features of Multilayer Switches

This topic identifies the features of multilayer switches.

Multilayer Switching
			Cisco.com
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* Combines functionality of: - Layer 2 switching - Layer 3 switching				e
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	1	Transport		4
- Layer 4 switching	3	Nñtwirk		3
* High-speed scalability				2
• Low latency	\	□ata Link
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© 2004, Cisco Systems, Inc. All rights reserved.			BCMS	N v2.1—1-36

Multilayer switching is hardware-based switching and routing integrated into a single platform. In some cases, the frame and packet forwarding operation is handled by the same specialized hardware ASICs and other specialized circuitry. A multilayer switch does everything to a frame and packet that a traditional switch and router does, such as the following:

Micro-segments collision domains

■ Provides multiple simultaneous switching paths Segments broadcast and failure domains

■ Provides destination specific frame forwarding based on Layer 2 information

■ Determines the forwarding path based on Layer 3 information

■ Validates the integrity of the Layer 2 frame and Layer 3 packet via checksums and other methods

■ Verifies packet expiration and updates accordingly Processes and responds to any option information

■ Updates forwarding statistics in the Management Information Base (MIB)

■ Applies security controls, if required Provides optimal path determination

The primary differences between the packet-forwarding operation of a router and multilayer switching operation of a multilayer switch are the physical implementation and the OSI layer of operations. The technologies of Layer 2 switching and Layer 3 forwarding are applied in a single platform.

Because it is designed to handle high-performance LAN traffic, a multilayer switch can be placed anywhere within the network, cost-effectively replacing the traditional switches and routers. Generally, however, a multilayer switch is more than is required in the Building Access submodule.

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