Practice Q's - MLS Flashcards
Which characteristics apply to multilayer switching? (Choose three.)
A. Uses CPU-based packet forwarding
B. Performs collision detection
C. Provides isolation of the collision domain
D. Provides Network-layer and Transport-layer access controls
E. Determines the forwarding path based on the Network layer address
Answer: C,D,E
Explanation:
Multilayer switching characteristics include determining the forwarding path based on the Network layer address (Layer 3), providing isolation of the collision domain (Layer 2); and providing Network-layer and Transport-layer access controls (Layers 3 and 4).
Multilayer switching combines the functionalities of Layer 2 switching and Layer 3 switching. Layer 3 switching is routing performed by hardware, specifically by utilizing application-specific integrated circuits (ASICs). The Layer 3 switch can perform all of the basic operations of traditional routers, including the following:
In contrast to Layer 2 switches, which provide the benefits of bridging, Layer 3 switches offer another high-performance packet switching solution.
CPU- based packet forwarding and collision detection are not unique characteristics of multilayer switching. CPU-based packet forwarding is not a concept used by routers or switches. Collision detection is a characteristic of Ethernet, which is not unique to multilayer switching.
Which of the following capabilities does a multilayer switch possess that an Access layer switch does not? (Choose all that apply.)
A. the ability to make forwarding decisions based on MAC addresses
B. the ability to make forwarding decisions based on host names
C. the ability to make forwarding decisions based on IP addresses
D. the ability to make forwarding decisions based on UDP/TCP port numbers
E. the ability to make forwarding decisions based on NetBIOS names
Answer: C,D
Explanation:
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:
When migrating to the Cisco Enterprise Composite model from earlier models, keep the following practices in mind:
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.
