OV 8 - 1 Copyright © 2013 Logical Operations, Inc. All rights reserved. LAN Infrastructure Switching Static IP Routing Dynamic IP Routing Virtual

OV 8 - 1Copyright © 2013 Logical Operations, Inc. All rights reserved.

LAN Infrastructure

Switching Static IP Routing Dynamic IP Routing Virtual LANs Plan a SOHO Network


Switches and Network Performance

Client 1 Server 1

Server 2 Client 2

Eight-port switch


Types of Switches

Switch Type Description

Cut-through

A switch that forwards a data packet as soon as it receives it; no error checking or processing of the packet is performed. This switch performs the address table lookup immediately upon receiving the destination address field in the packet header.

Fragment-freeA switch that scans the first 64 bytes of each packet for evidence of damage by a collision. If no damage is found, it forwards the packet; otherwise, discards it.

Store-and-forwardA switch that calculates the CRC value for the packet’s data and compares it to the value included in the packet. If they match, the packet is forwarded.

MultilayerA multilayer switch that performs both routing and switching functions. This type of switch is relatively new, and there is no industry standard to define what qualifies as a multilayer switch.

Content

A switch that is used for load balancing among server groups and firewalls, and web cache and application redirection. Content switches are often referred to as 4-7 switches as they primarily work on Layers 4 and 7 of the OSI model.


Circuit Switching Networks

Modem Modem

Path built when circuit is establishedPath built when circuit is established


Packet Switching Networks

Each packet finds its own route

Each packet finds its own route


Virtual Circuit Switching

Each packet carries a VCI on

a virtual path

Each packet carries a VCI on

a virtual path


Cell Switching Networks

Blank data fills the celluntil it reaches its fixed size

Blank data fills the celluntil it reaches its fixed size


Routing

Source DestinationBest path for sending the packetBest path for sending the packet


Static Routing

Source

Destination

209.16.88.4

200.200.200.200

R2

R1

Static route used to forward packets

Static route used to forward packets

209.16.88.0

DestinationRouter

200.200.200.0

R2

R1

IP Routing Table


Types of Routers

Router Type Description

Access routersRouters used in SOHO networks. They are located at customer sites and are inexpensive.

Distribution routers

Routers that collect data from multiple access routers and redistributes them to a enterprise location such as a company’s headquarters. The routing capabilities of a distribution router is higher than that of access routers.

Core routersCore routers are located at the center of the network backbones. They are used to connect multiple distribution routers located in different buildings to the backbone.


Routers vs. Switches

Switches: Use MAC addresses, which limits communication to adjacent networks Cannot determine data type

Routers: Use network maps, which enables communication with distant networks Can read port numbers and determine data type


Routing Tables


Routing Table Entries

UnicastUnicast

Default gateway forlocal loopback

Default gateway forlocal loopback

Network interface card

Network interface card

Local broadcastLocal broadcast

Local subnetLocal subnet

MulticastMulticast

Internetwork broadcast

Internetwork broadcast


Routing Entry Components

Network ID of destinationNetwork ID

of destinationMask for this entryMask for this entry

Address offirst hop

Address offirst hop

Local portaddress

Local portaddress

Route cost(in host)

Route cost(in host)


The route Command

Command Function

Route print Display the routing table entries.

Route add Add static entries.

Route delete Remove static entries.

Route change Modify an existing route.

Route –pMakes the specified route persistent across reboots, when used in conjunction with the add command.

Route -f Clears a routing table of all entries.


The Routing Process

Destination IP address does not change

Destination IP address does not change

MAC address changes on each hop

MAC address changes on each hop

Source 100.1.10.19

Destination 200.6.42.7

Subnet 1 Subnet 2 Subnet 3


Autonomous Systems

Leader of the autonomous system


A2 A3

A4

A5

A1

AS1

B2

AS2

C1

C2 C3

AS3

Dest Path

B1 AS2B2 AS2B3 AS2B4 AS2

Dest Path

C1 AS3

C2 AS3

C3 AS3

B1 Table

C1 Table

Dest Path

A1 AS1A2 AS1

A3 AS1

A4 AS1

A1 Table

A5 AS1

Inter-domain RoutingInter-domain Routing

Intra-domain RoutingIntra-domain Routing


Router Roles in Autonomous Systems

Interior routers on AS1

Interior routers on AS1

Routers on AS3 are exterior to AS1Routers on AS3 are exterior to AS1

Border routersbetween AS1

and AS3

Border routersbetween AS1

and AS3

Autonomous System 1

Autonomous System 2

Autonomous System 3


Routing Methods in Autonomous Systems

Routing Method Description

Inside an autonomous system

When routing inside an autonomous network, data transmission begins at a workstation and does not leave the AS. That means that when any node sends data, it can send it only to a node on the same local network. Nodes use ARP to obtain the local destination’s MAC address.

Between adjacent networks

Adjacent networks share border routers, and because any router inside an AS knows a direct path to the adjacent network, it knows how to deliver data to the correct border router.

Between distant networks

Distant networks are not directly aware of the location of a destination network. You have accessed a distant network if you have sent a request to the Internet for a web page.


Dynamic Routing

Routers perform route discovery operations. Routers transmit data to adjacent routers. Routing entries are dynamically created. Dynamically built routing tables show an accurate picture of a network as it is

updated more often.


Distance-Vector Routing

Distance denoted by hop countDistance denoted by hop countRouting information shared

among neighborsRouting information shared

among neighbors

To Cost

A 0B 5C 2D 3E 6

Next

---CC

Routing Table A

To Cost

A 3B 8C 5D 0E 9

Next

-AA-A

Routing Table D

To Cost

A 5B 0C 4D 8E 3

Next

---A-

Routing Table B

To Cost

A 6B 3C 4D 9E 0

Next

C--C-

Routing Table E

To Cost

A 2B 4C 0D 5E 4

Next

---A-

Routing Table C

A B

D E

C

3

2 4

5

3

4


Link-State Routing

Floods routing information to all routers within a network. Attempts to build and maintain a more complex route database. Broadcasts small updates and converge quickly. More expensive to implement. OSPF implements link-state routing.


Path-Vector Routing



A2 A3

A4

A5

A1

AS1

B2

AS2

C1

C2 C3

AS3

Dest Path

B1 AS1B2 AS1B3 AS1B4 AS1

Dest Path

C1 AS3

C2 AS3

C3 AS3

B1 Table

C1 Table

Dest Path

A1 AS1A2 AS1

A3 AS1

A4 AS1

A1 Table

A5 AS1


Route Convergence

Network becomesunreachable

Network becomesunreachable

Still thinks routeis good

Still thinks routeis good

Convergence

Change


Routing Loops

Updates the routingtable of the link

being down

Updates the routingtable of the link

being downAssumes that Router Bhas an alternate path

Assumes that Router Bhas an alternate path

A B C


Count-to-Infinity Loops

Occur when a router or network goes down and one of the other routers does not realize that it can no longer reach the route

Cause incorrect information broadcast


Router Discovery Protocols

Protocol Description

RIPA distance-vector routing protocol that is easy to configure, works well inside simple autonomous systems, and is best deployed in small networks with a fewer numbers of routers and in a non-dynamic environment.

RIP v2 RIP v2 enhances RIP by supporting next hop addressing, authentication, subnet mask, and multicast addressing.

BGPA path-vector routing protocol used to establish routing between ISPs. BGP is the routing protocol used to connect Internet backbones. BGP maintains a table of IP networks among autonomous systems.

IGRP A distance-vector routing protocol developed by Cisco® as an improvement over RIP and RIP v2.

EIGRPA proprietary routing protocol by Cisco and considered a hybrid type protocol. It includes features that support VLSM and classful and classless subnet masks.

OSPFA protocol that is used to accomplish link-state routing. Each OSPF router uses the information in its database to build the shortest possible path to destinations on the internetwork.

IS-IS

A link-state routing protocol that is natively an ISO network layer protocol. IS-IS is similar to OSPF (they both use Dijkstra’s algorithm) but IS-IS is able to support more routers than OSPF and does not support only a specific type of network address.


STP

STP establishes a cross-linked structure between branches


VLANs

Point-to-point connectionsPoint-to-point connections

LAN 1 LAN 2

LAN 3

VLAN


Types of VLANs

Type Computers are Configured to a VLAN Based on

Port-based VLANsThe ports that are a part of the VLAN. For example, in a switch with five ports, ports 1, 2, and 3 can be configured to belong to VLAN A and ports 4 and 5 belong to VLAN B.

MAC address-based VLANs

The MAC address of the computers. Switches are configured to identify the MAC addresses of individual computers connected to it. These MAC addresses are grouped to form the VLAN.

Subnet-based VLANs

The IP subnets that they belong to. The IP addresses are used only as references to identify computers that are to be configured to the VLAN.


VLAN Switch Functions

Subnet 1 Subnet 2 Subnet 3


VTP

VTP advertises switching information to all switches on a network

VTP advertises switching information to all switches on a network

D E

F

A B

C

A B

C

D E

F


SOHO Networks

Devices in SOHO networks

Devices in SOHO networks


SOHO Network Hardware

The list of requirements to implement a SOHO network are: 1 to 10 computers that are to be connected.Specialized connectivity devices.Printers, fax machines, access points, and biometric devices.An ADSL modem to connect to the Internet.For a wired SOHO, you need connecting cables of a length of 100 to 200 meters.


Reflective Questions

1. Of the LAN infrastructure technologies discussed in this lesson (bridges, switches, static routing, dynamic routing, filtering, and VLANs), which ones do you expect to work with the most? Why?

2. What do you see as the pros and cons of implementing static routing versus dynamic routing?

Documents

OV 8 - 1 Copyright © 2013 Logical Operations, Inc. All rights reserved. LAN Infrastructure Switching Static IP Routing Dynamic IP Routing Virtual