Vol 2 Part 4: Network Architecture

Question 1

What is a Campus LAN and explain how a Campus LAN is designed.

Answer 1

A Campus LAN refers to the LAN created to support devices in a building or in multiple buildings close together. Switches in each building are interconnected from floor to floor, and switches are used to interconnect multiple buildings.

Question 2

A switch that forwards frame from itself to the user is known as what kind of switch in a Campus LAN?

Answer 2

Access Switch

Question 3

What are the two types of switches that are connected to other switches in a campus LAN? Explain the differences between the two.

Answer 3

Distribution switches provide a path through which the access switches can forward traffic to each other, with each access switch needed to connect to at least one distribution switch.

A Core switch is utilized in a three tier campus design, and are expensive. A core layer is added, aggregating distribution switches in a very large Campus LAN. These core switches, while expensive, are extremely useful due to their high forwarding rates to handle larger volumes of traffic.

Question 4

Within a two-tier Campus LAN, what are the 4 commonly seen network topologies? Explain each topology as well.

Answer 4

1. Star- design with one central device connecting to several others. Not ideal, as the central device is a single point of failure.
2. Full mesh- all network nodes are connected to each other.
3. Partial Mesh- some network nodes are connected to each other.
4. Combined topology design concepts into larger more complex design. A two-tier campus LAN is typically a hybrid design, as it has a star and partial mesh.

Question 5

In a SOHO, the wireless device placed at the demarc is typically fulfilling what 3 roles all at once?

Answer 5

Firewall, switch, WAP

Question 6

What is Metro Ethernet (MetroE)?

Answer 6

Ethernet from customer to service provider (SP). Metro Ethernet includes a variety of WAN services, and operates at layer 2. Typically, Metro Ethernet is fiber optic ethernet, with a set of switches used to connect an enterprise network to the SP. Customers typically connect to via a router or layer 3 switch.

Question 7

What must be built throughout an area in a MetroE design in order to provide connectivity to the customer?

Answer 7

A point of presence

Question 8

The physical link between the customer and SP in a MetroE design is called a BLANK.

Answer 8

An access link

Question 9

In MetroE, everything that happens on an access link is called the BLANK.

Answer 9

user network interface

Question 10

Ethernet Line Service (E-Line) is a MetroE topology where two sites are connected via an access link. It is the simplest of MetroE topologies. What is required in order for an E-Line topology to work with respect to where the routers are located?

Answer 10

The routers must be in the same subnet as each other. This allows them to use routing protocols to become neighbors and exchange routes, creating a point-to-point ethernet virtual circuit (EVC).

Question 11

Ethernet Tree Service (E-Tree/Hub and Spoke) is a MetroE topology. Explain how this topology functions with respect to how the routers communicate?

Answer 11

A central site server, also known as the ROOT of the tree, is able to reach each remote LEAF site. These leaf sites can only send to the root. All leaf sites and root must be on the same subnet.

Question 12

What is Multiprotocol Label Switching (MPLS)?

Answer 12

MPLS is a WAN service used to route packets between customer sites. MPLS VPNs are sued to route private network traffic from various customer sites to remote sites.

Question 13

When using MPLS, edge routers are needed to add and remove the MPLS headers. What are the two types of edge routers used with MPLS, and explain the difference between the two.

Answer 13

Customer Edge (CE)- typically a router sitting at a customer site

Provider Edge (PE)- edge of the SPs network on the other end of the access link

Question 14

MPLS operates on what layer?

Answer 14

Layer 3

Question 15

Multiprotocol BGP (MPBGP) can be utilized in conjunction with MPLS. Why would we want to use MPBGP?

Answer 15

When you need to inject from one routing protocol to another (redistribution), MPBGP is extremely helpful, as you are able to, for example, take OSPF and inject the routes in MPBGP. This allows the Provider Edge (PE) router to become the next-hop router when needing to go across the WAN.

Question 16

What does DSL use as the access link for services?

Answer 16

The telephone links supplied by the telephone company (telco)

Question 17

What does the telco use with a Digital Subscriber Line (DSL) in order to differentiate between voice and data traffic on the same line?

Answer 17

a DSL access multiplexer (DSLAM)

Question 18

What is meant by the term asymmetric speeds with respect to your upload and download speeds?

Answer 18

Your download speed is faster than your upload speed

Question 19

What does cable internet use as the access link for services?

Answer 19

The cable tv cabling installed by your cable company

Question 20

Wireless Internet is a general term for internet services delivered how?

Answer 20

Via radio waves. Services from a mobile phone or any device that uses wireless technology with an integrated wireless network interface card.

Question 21

What are the different categories of wireless internet?

Answer 21

3G, 4G, LTE (part of 4G), 5G

Question 22

Virtual Private Networks (VPN) establish a private tunnel on a public network. Explain each of the 4 primary security features of VPNs.

Answer 22

Confidentiality- prevents man in the middle attacks by preventing 3rd parties from reading data

Authentication- verification that the sender is legitimate and not an attacking device

Data integrity- verification that the packet has not been changed

Anti-Replay- prevents MITM from copying and later replaying packets sent by a legitimate user in order to pose as a legitimate user

Question 23

VPN tunnels modify the original packet in order to add information to the packet so that the traffic is secure. Where in the packet does the VPN tunnel add this information?

Answer 23

In the packet’s header

Question 24

Rather than creating a VPN tunnel everytime a user wants to access a private network, networks can be configured with what protocol? What does this protocol give us that a normal VPN client does not? Where is this protocol configured?

Answer 24

IPSEC. This allows a 24/7 private connection, with an ability to be added to and changed over time in order to improve security functions. IPSEC can be configured in a router or a firewall.

Question 25

IPSEC encryption used two algorithms and uses a key as well. What are the two algorithms designed to do, and what is this key known as?

Answer 25

IPSEC uses an algorithm to encrypt the original data and one to decrypt the original data. A session key is needed, and is also referred to as a shared key, shared session key, or encryption key.

Question 26

Site to site VPN tunnels with IPSEC are created using what?

Answer 26

Generic routing encapsulation (GRE). Without IPSEC, the GRE tunnel would be unencrypted.

Question 27

Remote access VPNs often use what for session security? What port is this used on?

Answer 27

Transport Layer Security (TLS) on TCP port 443 (HTTPS).

Question 28

Which of the following are supported by MPLS?

a. OSPF
b. EIGRP
c. RIP
d. T1
e. All of the above

Answer 28

e. All of the above

Question 29

What does MPLS use in order to identify the various companies that a service provider services?

Answer 29

Labels

Question 30

In today’s day and age, servers are purchased or leased. Instead of a single OS for multiple applications, what can we use as a special OS to run the server hardware AND create independent virtual machines (VMs)?

Answer 30

A hypervisor

Question 31

When virtualizing a server, the CPU becomes split into cores. What are these cores referred to in this configuration, and what do these cores do?

Answer 31

The cores are known as vCPUs, with each core acting as a separate processor for each VM. In some cases, VMs with higher requirements can be assigned multiple cores or vCPUs.

Question 32

Not only can we virtualize servers, we can virtualize switches too! What methods can be used to supply the virtual switch, and what does the Cisco virtual switch’s configuration look like in comparison to a regular Cisco switch?

Answer 32

We can use the hypervisor to supply the virtual switch, or we can use the Nexus 1000VE from Cisco. The Nexus 1000VE has the same configuration as a normal switch!

Question 33

Could computing refers to products offered AND BLANK.

Answer 33

HOW they are offered

Question 34

The National Institute of Standards Technology (NIST) has 5 requirements for Cloud Computing. What are they?

Answer 34

1. on demand self service- the IT consumer can choose when to start and stop using the service without any direct interaction from the provider of the service
2. broad network access- the service must be available from many types of devices and over many types of networks, including the internet
3. resource pooling- the provider creates a pool of resources rather than dedicating specific servers for use only by certain customers. This pool of resources is dynamically allocated for each new request from a consumer
4. rapid elasticity- to the consumer, the resource pool appears to be unlimited and the requests for new services are filled quickly. In reality, the pool is NOT limited, but it expands quickly, known as “elastic”
5. measured service- the provider can measure the usage and report that usage to the consumer, both for transparency and for billing

Question 35

Clouds come in both a private and public form. What is the difference between the two?

Answer 35

Private clouds (on-premise) is a service created inside of a company, and the internal users are the customers. A cloud service catalogue exists for users, and everything is done in-house with engineers.

A public cloud are services offered to consumers in multiple companies, with consumers in different networks than the one which the public cloud resides in. The broad network access requirement (from NIST) means that a consumer’s access to services must come from nearly any connection.

Question 36

The Cloud’s “as a service model” consists of three categories. What are they?

Answer 36

Infrastructure as a service (IaaS)
Software as a service (SaaS)
(Development) Platform as a service (PaaS)

Question 37

Explain how IaaS works

Answer 37

The hardware specs are given to the cloud provider, an OS is chosen, and a VM is created and given to the customer, with any additional software needed left up to the responsibility of the customer.

Question 38

Explain how SaaS works

Answer 38

The consumer receives a service with already working software, with multiple VMs enabled for use. The consumer does not have control, and cannot see the VMs.

Question 39

PaaS is very similar to IaaS. Explain the key differences between the two.

Answer 39

PaaS comes with additional development tools as part of the service, as well as an integrated development environment (IDE) to code and test.

Question 40

When moving company services to the cloud, what is the biggest consideration you must account for?

Answer 40

Bandwidth to the internet