Topology Architecture Quiz

What is a characteristic of spine-and-leaf architecture?

• Each device is separated by the same number of hops

• It provides variable latency

• It provides greater predictability on STP blocked ports

• Each link between leaf switches allows for higher bandwidth

Answer explanation

pine-leaf architecture is typically deployed as two layers: spines (such as an aggregation layer), and leaves (such as an access layer). Spine-leaf topologies provide high-bandwidth, low-latency (-> Answer B is not correct), nonblocking server-to-server connectivity.

With a spine-and-leaf architecture, no matter which leaf switch to which a server is connected, its traffic always has to cross the same number of devices to get to another server (unless the other server is located on the same leaf) (-> Answer A is correct) . This approach keeps latency at a predictable level because a payload only has to hop to a spine switch and another leaf switch to reach its destination.

Reference: https://www.cisco.com/c/en/us/products/collateral/switches/nexus-7000-series-switches/white-paper-c11-737022.html

With Leaf-Spine, the network uses Layer 3 routing so STP is no longer required. (-> Answer C is not correct). Spine-leaf architectures rely on protocols such as Equal-Cost Multipath (ECPM) routing to load balance traffic across all available paths while still preventing network loops. This allows all connections to be utilized at the same time while still remaining stable and avoiding loops within the network.

What are two descriptions of three-tier network topologies? (Choose two)

• The core and distribution layers perform the same functions

• The access layer manages routing between devices in different domains

• The network core is designed to maintain continuous connectivity when devices fail

• The core layer maintains wired connections for each host

• The distribution layer runs Layer 2 and Layer 3 technologies

What benefit does controller-based networking provide versus traditional networking?

• moves from a two-tier to a three-tier network architecture to provide maximum redundancy

• provides an added layer of security to protect from DDoS attacks

• allows configuration and monitoring of the network from one centralized port

• combines control and data plane functionality on a single device to minimize latency

Which purpose does a northbound API serve in a controller-based networking architecture?

• communicates between the controller and the physical network hardware

• reports device errors to a controller

• generates statistics for network hardware and traffic

• facilitates communication between the controller and the applications

What is the name of the layer in the Cisco borderless switched network design that is considered to be the backbone used for high-speed connectivity and fault isolation?

• data link

• access

• core

• network

• network access

Answer explanation

The key layers are access, distribution, and core. The core layer is the network backbone that hierarchically connects several layers of the network design, providing for connectivity between end devices, computing and data storage services located within the data center and other areas, and services within the network.

A company needs to interconnect several branch offices across a metropolitan area. The network engineer is seeking a solution that provides high-speed converged traffic, including voice, video, and data on the same network infrastructure. The company also wants easy integration to their existing LAN infrastructure in their office locations. Which technology should be recommended?

• VSAT

• ISDN

• Frame Relay

• Ethernet WAN

Answer explanation

Ethernet WAN offer the ability of using Ethernet over long-distance links.

Which two WAN architecture options help a business improve scalability and reliability for the network? (Choose two)

• dynamic routing

• static routing

• dual-homed branches

• single-homed branches

• asychronous routing

Answer explanation

Dual-homed branches (branches connects to two ISPs or one ISP with two connections) increases reliability for the network.

Dynamic routing automatically use backup routes in the case of main routes fail which increases reliability. The configuration is remain unchanged or change a little when we expand the network thus increasing the scalability.

Note: A scalable network can expand quickly to support new users and applications without impacting the performance of the service being delivered to existing users

Which WAN access technology is preferred for a small office / home office architecture?

• broadband cable access

• frame-relay packet switching

• dedicated point-to-point leased line

• Integrated Services Digital Network switching

Which two functions are performed by the core layer in a three-tier architecture? (Choose two)

• Provide direct connectivity for end user devices

• Police traffic that is sent to the edge of the network

• Provide uninterrupted forwarding service

• Inspect packets for malicious activity

• Ensure timely data transfer between layers

Answer explanation

Considerations at the core layer include
+ Providing high-speed switching (i.e., fast transport)
+ Providing reliability and fault tolerance
+ Scaling by using faster, and not more, equipment
+ Avoiding CPU-intensive packet manipulation caused by security, inspection, quality of service (QoS) classification, or other processes

Which function is performed by the collapsed core layer in a two-tier architecture?

• applying security policies

• marking interesting traffic for data polices

• enforcing routing policies

• attaching users to the edge of the network

Answer explanation

The three-tier hierarchical design maximizes performance, network availability, and the ability to scale the network design.
However, many small enterprise networks do not grow significantly larger over time. Therefore, a two-tier hierarchical design where the core and distribution layers are collapsed into one layer is often more practical. A “collapsed core” is when the distribution layer and core layer functions are implemented by a single device. The primary motivation for the collapsed core design is reducing network cost, while maintaining most of the benefits of the three-tier hierarchical model.

A collapsed core network is shown below. The collapsed core network may be deployed with redundant core/distribution router, or consolidated core/distribution router.

Deploying a collapsed core network results in the distribution layer and core layer functions being implemented in a single device. The collapsed core/distribution device must provide the following:
+ High speed physical and logical paths connecting to the network
+ Layer-2 aggregation and demarcation point
+ Define routing and network access policies -> Answer C is correct
+ Intelligent network services—QoS, Network virtualization, etc.