Module 1 Lesson 2 Types of Network Topologies Main Ideas

Frame Relay

A Layer 2 protocol that interconnects sites using virtual circuits. These virtual circuits are identified by numbers called data-link connection identifiers (DLCI).

Asynchronous Transfer Mode (ATM)

A Layer 2 protocol that interconnects sites using virtual circuits. Virtual circuits were known by numbers called Virtual Path Identifiers (VPI's) and Virtual Circuit Identifiers (VCI's).

What is a VPI?

A Virtual Path Identifier; it identifies a logical path which can contain multiple virtual circuits.

Star Topology

A central node controls all message traffic

Point to Point Protocol (PPP)

A common Layer 2 protocol offering features such as multilink interface, looped link detection, error detection, and authentication. Authentication is used unlike HDLC.

Metropolitan Area Network (MAN)

A large computer network usually spanning a city that uses Metro Ethernet.

Encapsulation

Keeping details (like data and procedures) together in one part of a program so that programmers working on other parts of the program don't need to know about them.

LSR

Label Switch Routers; within the cloud and focused on just labels.

What are the Cons of Metro Ethernet?

Limited Availability typically only in metropolitan areas

What is the purpose of the spine in a Spine Leaf Design?

It's responsible for interconnecting all leaf switches and is the backbone of the network.

Collapsed Core Architecture

A 2 tier topology where the core and distribution layers have been merged.

Three-tier architecture

A network topology divided into Access, Distribution, and Core layers

Multiprotocol Label Switching (MPLS)

A routing technique that directs data on short path labels rather than network addresses. Keeps data traffic seperate.

Where do the sites generally connect out to in a WAN topology?

A service Provider

What is the difference between a solid and dotted connection?

A solid line represents a connection that is always up. A dotted connection represents a connection that is brought up on demand.

What is a VCI?

A virtual circuit identifier (VCI) identifies the unique logical circuit within a virtual path.

Distribution layer

Aggregation point for all Access layer devices.

Application-Centric Infrastructure (ACI)

Cisco's data center software defined networking (SDN) solution for data center environments.

High Level Data Link Control (HDLC)

Cisco's default Layer 2 encapsulation on serial interfaces.

Spine Leaf Design

Consists of 2 switching layers; a spine and a leaf.

CE

Customer edge; sits on the edge of network.

How does Metro Ethernet, despite its large scale, keep its customers traffic separate?

Each customer would be given a different wavelength of light (lambda/λ)

Point-to-Point

Interconnects 2 devices and typically uses a layer 2 protocol. Could be a physical or a logical connection through service providers cloud.

Core Layer

Network Backbone; Connects all distribution layer devices. Concerned with speed.

What is the benefits of a Partial Mesh topology compared to a full Mesh topology?

Partial Mesh is less expensive to implement and yields less redundancy than a full mesh topology.

What are the 5 types of WAN connectivity?

Point to Point Point to Multipoint Internet (w VPN) MPLS (Metro Protocol Label Switching) Metro Ethernet

PE (ELSR)

Provider edge/ Edge Label Switch Routers; sits on the edge of provider network and can make fording decisions based on labels rather than IP addresses.

What is the advantage of using the Internet with VPN when establishing a WAN?

Provides Privacy over the public Internet Low cost and widely available

Partial Mesh Topology

Some devices are connected to many devices but others are connected to 1 or 2.

Wide Area Network (WAN) Topology

Spans a large geographic area and are traditionally slower than LAN.

Top of Rack switch (ToR) switches

Switches that reside at the top of a data center cabinet and connects to each server in that cabinet.

Access Layer

This layer provides network access.

What is the purpose of the leaf in a Spine Leaf Design?

To connect to every spine switch and to connect out to a node.

Point to Multipoint

Topology in which one device communicates with more than one other device on a network.

What are the benefits of Metro Ethernet?

Very fast and redundant

What is a benifit of MPLS?

the ability to use packet-switched technologies over traditionally circuit-switched networks.