Chapter 8 - Wide Area Networks Flashcards
What is a Wide Area Network (WAN)?
- Networks and hosts are spread out over large distances (country or continent wide).
- Interconnect several MANs
- Typically owned by network providers
- Inter-processer distance 1000+ km
Describe the link type that the WAN usually uses
- Typically fiber
- Possibly microwave
- Link speed of 1 to 40 Gb/s (Ethernet); 622 Mb/s to 39.8 Gb/s (SONET); 54 – 170 Mb/s (Microwave)
Draw the WAN topology
See Slide 2 of IT Infrastructure Diagrams Keynote
Draw the WAN services view diagram
See Slide 3 of IT Infrastructure Diagrams Keynote
Name two common carrier services regulatory bodies.
Canadian Radio-Television and Telecommunications Commission (CRTC)
Federal Communications Commission (FCC)
What are the four main WAN circuit types?
- Circuit switched
- Dedicated circuit
- Packet switched
- Virtual Private Network
Describe the circuit switched network
- Uses the Public Switched Telephone Network
- (according to the textbook it uses a cloud architecture)
- Oldest WAN service
- Dial up
What are the two types of circuit switched networks?
Dial-up:
- Plain Old Telephone Service (POTS)
- Integrated Services Digital Network (ISDN)
What are the two main problems with circuit switched networks?
- Each time you want to transfer data you have to create a new connection
- The data rates are low
Describe dedicated circuit networks (also called leased line or private line service)
- Creates a point-to-point link between two customer locations.
- Ends of link are terminated by a Customer Premises Equipment (CPE)
- Typically billed a flat fee per month for unlimited use.
Draw the textbook diagram of a dedicated circuit network topology
See Slide 4 of the IT Infrastructure Diagrams Keynote
What are the three basic dedicated circuit network architectures? Draw them.
- Ring (slide 7 of diagrams keynote): Linked in a ring topology. Can be rerouted around a failed link.
- Star (slide 8 of diagrams keynote): customer cites are linked through a central router (can become a bottleneck). Link failure only affects one location.
- Partial/Full Mesh (slide 9 of diagrams keynote): each customer site has multiple links to other customer sites. More expensive.
What are the two main services of dedicated circuit networks?
- T-Carrier
- SONET
- both use time division multiplexing
What type of network is likely going to replace SONET?
Optical Transport Network (OTN)
Draw the basic architecture of a Packet Switched Network
See slide 12 of the IT Infrastructure Diagrams slide deck
What are the main differences between Circuit Switched Networks and Packet Switch Networks?
Circuit Switched: physical circuit connects two endpoints of customer premises equipment and is not shared by any other devices.
Packet Switched: Multiple data streams from different connections share the same physical connection.
What are the four types of packet switched services
- Asynchronous Transfer Mode (ATM) (legacy)
- Frame Relay (legacy)
- Multiprotocol Label Switching (IP/MPLS)
- Ethernet Services
Name some advantages of ethernet services
- Ethernet technology is ubiquitous - it works with existing infrastructure.
- It represents a simplified network design and management
Name three types of ethernet services
- Metro internet
- Wide Area Ethernet (WAE)
- Virtual private LAN Service
Packet switched network: Describe Multi-Protocol Label Switches
Allows carriers to define a specific path through the core network for a particular customer’s data. It requires special routers and headers.
What are the three special headers needed for Multi-Protocol Label Switches (MPLS)?
- Insert label
- Switch label
- Remove label
Multi-Protocol Label Switch (MPLS) are sometimes called ____________
Layer 2.5
What are the three Multi-Protocol Label Switch (MPLS) services?
- MPLS Virtual Private LAN Service
- Virtual Leased Line (VLL)
- Virtual Private Routed Network (VPRN)
What is a Virtual Private Network? Draw a diagram
- Creates a private tunnel through the common carrier network.
- Can be either provider or customer provisioned
- see slides 18-19 for diagram
How does a customer provisioned VPN differ from a provider provisioned VPN?
Customer provisioned VPN:
- uses customer provided and managed equipment.
- user computer must run VPN software that is compatible with the VPN gateway
What is IPsec VPN? draw a supporting diagram
IPsecurity VPN:
- uses customer provided and managed VPN gateway to terminate VPN connections
- user computer runs IPsec software provided by gateway vendor
- IPsec encapsulates and encrypts data sent between PC and gateway
What are the three main types of IPsec VPNs?
- Intranet VPN
- Extranet VPN
- Access VPN
What are three main factors to consider when purchasing WAN services?
- effective data rates and cost
- reliability
- network integration
Name some ways to improve performance for WANs.
- Upgrade routers that connect to the WAN
- Analyse traffic to find circuits approaching capacity
- Examine why circuits are at capacity
- Shift Network Usage
- Redesign the network
