Which of the following capabilities does a multilayer switch possess that an Access layer switch does not? (Choose all that apply.)
- the ability to make forwarding decisions based on MAC addresses
- the ability to make forwarding decisions based on host names
- the ability to make forwarding decisions based on IP addresses
- the ability to make forwarding decisions based on UDP/TCP port numbers
- the ability to make forwarding decisions based on NetBIOS names
Multilayer switches are capable of making forwarding decisions based on IP addresses and UDP/TCP port numbers, while Access layer switches are not. The term multilayer describes the ability of the multilayer switch to utilize information that exists on more than one layer of the TCP model for forwarding decisions. This device combines the functionality of a switch and a router. Additionally, it possesses the ability to do something that neither a switch or router alone: perform Fast Switching, a process whereby the device can route the first packet in a traffic flow and then use hardware switching for the remaining packets in the flow. This process of routing once, switching many, results in less routing (a slower process) and more switching (a faster process), with a net result of speeding traffic flow.
Multilayer switches usually operate in the Distribution and Core layers of the Cisco Enterprise Composite model. There are important considerations for each layer:
- Access layer – This is the layer where end-user stations should connect. It consists of Access layer or Layer 2 switches. VLANs, QoS, and protocol filtering operate at this layer.
- Distribution layer – This is the layer where routing is performed and where access lists are enforced. Devices in this layer operate in Layer 3 of the OSI model.
- Core layer – High-speed backbone switches exist on this layer. It should be designed with a low number of Layer 3 peers, switches that can efficiently forward traffic even when every uplink is at 100% capacity and the switches should have many high-speed ports.
When migrating to the Cisco Enterprise Composite model from earlier models, keep the following practices in mind:
- Add redundancy between the hierarchical layers
- Identify groups of end users as switch blocks
- Group common resources into switch blocks
Multilayer switches are also capable of making forwarding decisions based on MAC addresses, but access layer switches can do this as well.
Neither multilayer switches nor Access layer switches can make forwarding decisions based on host names or NetBIOS names. This function is performed by Domain Name Servers (DNS) and Windows Internet Naming (WINS), servers respectively.
Layer 2 Technologies
Configure and verify switch administration