1-2 - VPN Fundamentals

Question 1

Advantages of VPNs

Answer 1

• cost savings
• scalability
• improved security
• better performance
• flexibility and reliability
• greater access to mobile users

Question 2

provider network

Answer 2

common infrastructure owned by service providers that are used to offer VPN services to customers

Question 3

customer network

Answer 3

• exclusively under customer control
• consists of routers at various customer sites
• routers that connect the sites of individual customers to the service provider network are called customer edge routers

Question 4

customer sites

Answer 4

sites that are contiguous parts of the customer network

Question 5

P device

Answer 5

device on the provider network with no customer connectivity

Question 6

PE device

Answer 6

device on provider network to which customer devices are connected

Question 7

PE-CE link

Answer 7

the link between a PE router and a CE router

Question 8

CE device

Answer 8

device in the customer network that links to the provider network (a.k.a. CPE)

Question 9

VPN models

Answer 9

overlay: SP provided VCs between customer sites as a replacement for dedicated P2P links
peer-to-peer: SP actively participates in customer routing

Question 10

Examples of Overlay VPNs (L2 and L3)

Answer 10

L2:
X.25
Frame Relay
ATM

L3:
GRE
DMVPN
IPsec
L2TPv3
SSL VPN

Question 11

Peer-to-peer VPN examples

Answer 11

• ACLs (shared router)
• split routing (dedicated router)
• GET VPN
• MPLS VPN

Question 12

Describe MPLS L2VPNs

Answer 12

• Enable the SP to offer P2P or MP2MP L2 connections between distant customer sites
• consolidate L2 traffic such as Ethernet, Frame Relay, ATM, HDLC, and PPP over an IP or MPLS network
• no IP signaling is needed between the customer and provider

Question 13

Describe MPLS L3VPNs

Answer 13

• customer peers with the service provider at the IP Layer 3 level
• uses private, IP-based service offering from service provider
• they must establish IP routing (static or dynamic) to exchange routing info between customer sites that belong to the same VPN
• VRF instances isolate customer routing information
• MPLS seamlessly provides any-to-any connectivity between sites that belong to the same VPN

Question 14

Intra-AS VPN

Answer 14

single ASN provides connectivity between sites that belong to a single company

Question 15

Inter-AS VPN

Answer 15

• allows service providers that run separate networks to jointly offer MPLS VPN services to the same end customer
• can begin at one customer site and traverse multiple service provider backbones before it arrives at another customer site

Question 16

What are the two basic VPN implementation models?
A. GET and MPLS
B. ACL and split routing
C. overlay and peer-to-peer
D. access and aggregation

Answer 16

C