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CCNA > Chapter 43 - WAN Architecture > Flashcards

Chapter 43 - WAN Architecture Flashcards

1
Q

What is MetroE?

A
  • A subset of various layer 2 WAN services
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2
Q

What is an Access/Ethernet Access link?

A
  • The physical link between a customer and an SP (Service Provider)
  • Also known as a UNI (User Network Interface)
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3
Q

What are some of the Ethernet standards that access links may use to connect from SPs to customers?

A
  • 100BASE-LX10 - 100mbps - 10km
  • 1000BASE-LX - 1Gbps - 5km
  • 1000BASE-LX10 - 1Gbps - 10Km
  • 1000BASE-ZX - 1Gbps - 100Km
  • 10GBASE-LR - 10Gbps - 10Km
  • 10GBASE-ER - 10Gbps - 40Km
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4
Q

What is Ethernet Line Service?

A
  • Also known as E-Line or VPWS (Virtual Private Wire Service)
  • Point to point topology
  • Two sites can exchange Ethernet frames.
  • Similar to a Leased Line
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5
Q

What is an Ethernet LAN Service?

A
  • Also known as E-LAN or VPLS (Virtual Private LAN Service)
  • Full mesh topology
  • WAN service that acts like a LAN in that all devices can send frames to all other devices
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6
Q

What is an Ethernet Tree Service?

A
  • Also known as E-Tree
  • Hub and spoke/Partial mesh/Point to multipoint topology
  • A central site (root) can communicate to a set of remote sites (leaf) but the remote sites cannot communicate directly
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7
Q

True or False. Routers involved in a Metro Ethernet service must have an interface that has an IP in the same subnet as the other routers.

A

True.

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8
Q

What is MPLS?

A
  • Multiprotocol Label Switching
  • MPLS labels are applied to packets upon entering the MPLS network and are removed upon leaving
  • These allow the devices in the MPLS topology to create separate MPLS VPNs for different customers to ensure that different customers’ traffic does not mix
  • Technically a Layer 3 protocol, however, as the MPLS header is applied between the layer 2 and layer 3 header, it is sometimes called a layer 2.5 protocol
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9
Q

What are MPLS VPNs?

A
  • Make it possible to stop packets from leaking between customers and also means that routes learned from one customer can be separate to routes learned from another in an MPLS network
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10
Q

How does an MPLS WAN service interact with a customer?

A
  • Uses a routing protocol to build neighbor relationships and share/learn routes with customer routers
  • Advertises a customer’s routes to other routers utilising the same MPLS VPN
  • Makes decisions about MPLS forwarding, including what labels to add, based on the customer’s address space
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11
Q

What is MPLS P, CE and PE?

A
  • P - Provider Core Router
  • CE - Customer Edge - Typically a router located at the customer’s site
  • PE - Provider Edge - Sits at the edge of the SPs network
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12
Q

Benefits of MPLS and Metro Ethernet

A
  • MPLS can use any layer 2 protocol as the edge device will generally be a router that only needs access to the packet to function so can discard any layer 2 header. Metro Ethernet has to use Ethernet as SP devices for the service are layer 2 and will not discard the header so all devices along the service need to be able to read the same header.
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13
Q

What happens between CE and PE routers over an MPLS VPN in relation to routing protocols?

A
  • CE routers become neighbors with PEs but not with other CEs
  • The MPLS network advertises CE routes between other PEs so that CEs can route to other CEs
  • The above is true unless it is a layer 2 MPLS VPN
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14
Q

True or False. Route redistribution is required by PEs when using an MPLS VPN and the CE-PE routing protocol is not BGP.

A

True. A variation of BGP is used called MPBGP (Multi Protocol Border Gateway Protocol)

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15
Q

What is a benefit of using MPBGP at PE equipment instead of another router protocol?

A
  • It can advertise routes from multiple customers connected to the PE while keeping the routes logically separated so they are only advertising the correct routes to the correct customers.
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16
Q

What is a DSLAM?

A
  • DSL Access Multiplexer
  • Used in DSL internet connectivity to split the voice and digital signal out from each other
17
Q

What is LTE?

A
  • Long-Term Evolution
  • A newer and faster mobile data technology that is considered to be part of 4G
18
Q

What are some of the features offered by Internet VPNs?

A
  • Confidentiality/Privacy - Preventing anyone in the middle of the connection from accessing the data
  • Authentication - Verifying that the sender of the packet is a legitimate device
  • Data Integrity - Verifying that the packet was not changed in transit
  • Anti-Replay - Preventing a man in the middle from copying and later replaying data sent by a legitimate user in an attempt to appear as that legitimate user
19
Q

What is IPSec?

A
  • A framework that defines how two devices can achieve, confidentiality, authentication, data integrity, and anti-replay when sending data between each other
  • Uses two formulas. One to encrypt data and another to decrypt this data.
  • Encapsulates the data and original IP header in a VPN header and new IP header.
20
Q

What is an Encryption Key?

A
  • Also known as Session Key, Shared Key, or Shared Session Key
  • Cipher that is used to encrypt and decrypt IPSec packets
21
Q

Benefits of using GRE over IPSec instead of just GRE or IPSEC alone.

A
  • IPSec allows unicast packets to traverse its tunnel. If for example you wanted to allow routing protocols to communicate, you would need to use GRE over IPSec as GRE allows multicast and broadcast.
  • GRE does not encrypt traffic so it is better to use GRE over IPSec for added security.
22
Q

What is GRE?

A
  • Generic Routing Encapsulation
  • VPN tunnel protocol that allows unicast, multicast, and broadcast traffic as well as many Layer 3 protocols
23
Q

What are differences between a site-to-site VPN and a remote access VPN?

A
  • Site-to-site VPNs are generally permanent whereas remote access VPNs on demand
  • Remote access VPNs will normally also support a single user per connection but a site to site VPN could have multiple users at each site communicating over the tunnel
  • Protocols such as IPSec can be used for site-to-site
  • Protocols such as TLS can be used for remote access
24
Q

What is a WAN?

A
  • A network that spans over a large geographical area. E.g. The Internet
  • Used to connect geographically separate LANs
25
Q

What does T1, T2, and T3 refer to?

A
  • Leased Line tiers used in America. The European versions are E1, E2, and E3.
  • The higher the tier, the higher the bandwidth
26
Q

True or False. MPLS networks use the destination IP to decide how to forward traffic.

A

False. They use the MPLS label when routing within the MPLS network.

27
Q

What is the difference between Layer 2 MPLS VPNs and Layer 3 MPLS VPNs?

A
  • On layer 2, the MPLS network is essentially transparent. Both CE connected by the MPLS network will peer with each other via routing protocols and must have IPs in the same subnet to communicate.
  • On layer 3 the CE equipment peers with the PE equipment via routing protocols and the connected interfaces on the CE and PE equipment are in the same subnet.
28
Q

List forms of internet connectivity

A
  • CATV (Cable) - Using TV infrastructure to connect to the internet
  • DSL (Digital Subscriber Line) - Using telephone infrastructure to connect to the internet
  • Leased Line
  • Ethernet WAN
  • 4G/5G/LTE
  • Internet VPN
29
Q

Define Single Homed

A
  • Single internet connection to 1 ISP
  • No resilience
30
Q

Define Dual Homed

A
  • Two internet connections to 1 ISP
  • Some resilience
31
Q

Define Multi Homed

A
  • One internet connection to 2 ISPs (one per ISP)
  • Very resilient
32
Q

Define Dual Multi Homed

A
  • Two internet connections to 2 ISPs (two connections to both ISPs)
  • Most resilient
33
Q

Why should VPNs be used when establishing WANs over the internet?

A
  • There is no inherent security as opposed to using MPLS (which separates customer traffic using labels) or a leased line (which is a dedicated connection between two LANs)
34
Q

What is DMVPN

A
  • Dynamic Multipoint VPN
  • Cisco made
  • Dynamically creates a full mesh of IPSec tunnels between sites based on information used when creating IPSec tunnels between each site and a ‘hub site’.
35
Q

Differences between IPSec Transport mode and Tunnel mode

A
  • Transport mode does not encrypt the IP header. Only the payload. Tunnel encrypts both
  • Tunnel mode is better for NAT-T
  • Tunnel mode requires additional headers

CCNA (50 decks)

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