CCNA Sessão 2_mac_b

CCNACisco Certified Network Associate

- CIDR- Subnetting- VLSM- Route summarization- Troubleshooting ip address

Private Addresses

Public Addresses

Classless Inter-Domain Routing (CIDR)Method that ISPs (Internet Service Providers) use to allocate

an amount of addresses to a company.CIDR is telling you what your subnet mask is.

The slash notation (/) means how many bits are turned on (1s)

SUBNETTING

SubnettingThe ability to divide the original host portion of the address into the new subnet and host fields provides addressing flexibility for the network administrator.

From the outside, a LAN is seen as a single network with no details of the internal network structure.

Advantages of SubnettingReduced network trafficOptimized network performanceSimplified managementFacilitated spanning of large geographical distances

Provide broadcast containment Low-level security on the LAN

Decimal Equivalents of 8-Bit Patterns

Subnetworks

Subdividing the Host Octets of a Class A Address

Subdividing the Host Octets of a Class B Address

Subdividing the Host Octets of a Class C Address

How to Create Subnets1. Determine the number of required network IDs:

- One for each subnet- One for each wide area network connection

2. Determine the number of required host IDs per subnet:- One for each TCP/IP host- One for each router interface

3. Based on the above requirements, create the following:- One subnet mask for your entire network- A unique subnet ID for each physical segment- A range of host IDs for each subnet

Example of subneting

Necessary subnets - 6

- 3 for Wan connections

- 3 for LANs

Number of required host IDs per subnet

n is the number of borrowed digits

x is the number of digits for the hosts

2 nTotal number of subnets =

Total number of hosts =

2 - 2x

Subnets3 bits emprestados: 23 = 8 subnets4 bits emprestados: 24 = 16 subnets5 bits emprestados: 25 = 32 subnets6 bits emprestados: 26 = 64 subnets

Hosts utilizáveis3 bits emprestados sobram 5: 25 -2 = 30 Hosts4 bits emprestados sobram 4: 24 -2= 14 Hosts5 bits emprestados sobram 3: 23 -2 = 6 Hosts6 bits emprestados sobram 2: 22 -2 = 2 Hosts

Determine the Subnet MaskDetermines which part of an IP address is the

network field and which part is the host field.Follow these steps to determine the subnet mask:

1. Express the subnetwork IP address in binary form.

2. Replace the network and subnet portion of the address with all 1s.

3. Replace the host portion of the address with all 0s.

4. Convert the binary expression back to dotted-decimal notation.

Subnet mask in decimal = 255.255.240.0

Subnet Mask

Class B address with 8 bits borrowed for the subnet

130.5.2.144 (8 bits borrowed for subnetting) routes to subnet 130.5.2.0 rather than just to network 130.5.0.0.

Determining Subnet Mask Size

The address 197.15.22.131 would be on the subnet 197.15.22.128.

11000101

00001111

00010110

100 00011

Network Field SNHost Field

Class C address 197.15.22.131 with a subnet mask of 255.255.255.224 (3 bits borrowed)

Determining Subnet Mask Size

Subnetting Example with AND Operation

Depois de achar a subnet mask é necessário definir o seguinte:

1- Quantas subnets é possivel obter com essa subnet mask?

2- Quais são os hosts válidos?

3- Quais as subnets válidas?

4- Qual o broadcast address de cada subnet?

5- Quais os hosts válidos em cada subnet?

Realizar subnetting

Case Study

A empresa Rumos Angola mudou-se de instalações para um novo edifício com 3 andares. Foram reorganizados todos os serviços. Assim no primeiro andar ficaram situadas as salas de aulas. No segundo foi destinado às salas dos formadores e no ultimo piso os serviços administrativos. Ao administrador de rede foi dado um endereço privado de classe C (192.168.10.0) para que criasse o endereçamento IP de forma a permitir conectividade entre todos os utilizadores desta nova rede, conforme desenho em anexo. Não se prevê o aumento do número de utilizadores.

Nº máximo de utilizadores por rede – 28

Nº de bits necessários para os hosts- 5

Nº de sub-redes necessárias- 6

Nº de bits necessários para obter as subnets- 3

Case Study- Resolução

2 - 2=30

5

2 =83

192.168.10.0

255.255.255.0

11111111.1111111.1111111.11100000

Endereço privado de Classe C

Calculo da subnet mask

128+64+32= 224

255.255.255.224

7

6

5

4

3

2

1

0

Broadcast Host RangeSubnet IDSubnet

192.168.10.32

192.168.10.224

192.168.10.192

192.168.10.160

192.168.10.128

192.168.10.96

192.168.10.64

192.168.10.0 192.168.10.31

192.168.10.255

192.168.10.223

192.168.10.191

192.168.10.159

192.168.10.127

192.168.10.95

192.168.10.63

.1-.30

.225-.254

.193-.222

.161-.190

.129-.158

.97-.126

.65-.94

.33-.62

Determinação das redes e dos hosts

Representação em Decimal

Representação em binário

ID Rede 0 192.168.10.0 11000000 10101000 00001010 000000001º Host 192.168.10.1 11000000 10101000 00001010 00000001Ultimo Host 192.168.10.30 11000000 10101000 00001010 00011110

Broadcast 192.168.10.31 11000000 10101000 00001010 00011111


Broadcast 192.168.10.63 11000000 10101000 00001010 00111111


Broadcast 192.168.10.95 11000000 10101000 00001010 01011111. . . . . .. . . . . .. . . . . .


Broadcast 192.168.10.255 11000000 10101000 00001010 11111111

Endereçamento final

IP Subnetting

IP Subnetting

Subnet

Broadcast

IP Subnetting

IP Subnetting

00000000.0000000

00000001.11111111

00000010.0000000

00000011.11111111

IP Subnetting

00000000.0000000

00000000.01111111

IP Subnetting

Variable Length Subneeting Mask- VLSM

VLSM overviewAs IP subnets have grown, administrators have

looked for ways to use their address space more efficiently

With VLSM, a network administrator can use a long mask on networks with few hosts, and a short mask on subnets with many hosts

VLSM allows an organization to use more than one subnet mask within the same network address space

VLSM implementation maximizes address efficiency, and is often referred to as subnetting a subnet

A Waste of Space

When to Use VLSM?

A Working VLSM Example

172.16.33.0/30

Configuring VLSM

VLSM

16

VLSMUse a Class C network address 192.168.10.0 for the following network

VLSM

14

30

20

6

VLSMVLSM

Exercicio- Realizar endereçamento IP a partir da rede 172.24.1.0

Route summarization reduces the burden on upstream routers

Complex hierarchy of variable-sized networks and subnetworks is summarized at various points with a prefix address, until the entire network is advertised as a single aggregate route

Route summarization, or supernetting, is only possible if the routers of a network use a classless routing protocol, such as OSPF or EIGRP

Route Summarization

Route Summarization

ExercícioAddress First

octetSecond octet

Third octet

Fourth octet

172.16.0.0

172.16.2.0

172.16.3.128

172.16.4.0

172.16.4.128

Troubleshooting IP Addressing

Troubleshooting IP addressing issues

ping uses the ICMP protocol to verify the hardware connection and the IP address of the network layer. This is a basic test mechanism.

telnet verifies the application layer software between a source and a destination. This is the most complete test mechanism available.

traceroute locates failures in a path from a source to a destination. This command uses Time to Live values to generate messages from each router along a path.

Testing Local StackPing is a utility for testing IP connectivity

between hostsPing sends out requests for responses

from a specified host addressIf the host at the specified address

receives the Echo request, it responds with an ICMP Echo Reply datagram.

After all the requests are sent, the ping utility provides an output with the summary of the responses.

Troubleshooting IP addressing is obviously an important skill.

Four troubleshooting steps Cisco recommends:1- Open a DOS window and ping the

diagnostic, or loopback, address (127.0.0.1)2- From the DOS window, ping the IP address

of the local host.3- From the DOS window, ping the default

gateway (router).4- If steps 1 through 3 were successful, try to

ping the remote server.

Troubleshooting IP Addressing

Ping command

Pinging the Local Loopback

For testing the internal configuration of IP on the local host ping the special reserve address of local loopback (127.X.X.X).

A response from 127.X.X.X indicates that IP is properly installed on the host.

Ping the GatewayTest the host ability to communicate on the local

network. Ping the IP address of the gateway of the host.

Ping remote hostYou can also use ping to test the ability of the local IP

host to communicate across an internetwork. Ping an operational host of a remote network,

Traceroute (tracert)Traceroute (tracert) is a utility that allows us to observe

the path between the hosts.The trace generates a list of hops that were successfully

reached along the path.

Traceroute (tracert)The first sequence of messages sent from traceroute

will have a TTL field of one. This causes the TTL to time out the packet at the first router. This router then responds with an ICMP Message. Traceroute now has the address of the first hop.

Traceroute then progressively increments the TTL field (2, 3, 4...) for each sequence of messages. This provides the trace with the address of each hop as the packets timeout further down the path. The TTL field continues to be increased until the destination is reached or it is incremented to a predefined maximum.

Once the final destination is reached, the host responds with either an ICMP Port Unreachable message or an ICMP Echo Reply message instead of the ICMP Time Exceeded message.

Telnet is a virtual terminal protocol that is part of the TCP/IP protocol suite

Allows connections to be made to remote hosts Telnet is an IOS EXEC command used to verify

the application layer software between source and destination

This is the most complete test mechanism available

Telnet

Telnet

Establishing Telnet ConnectionsA host name table or access to DNS for Telnet

must be present for a name to work. Otherwise, the IP address of the host must be entered.

Denver>connect parisDenver>parisDenver>131.108.100.152Denver>telnet paris

Telnet can be used to perform a test to determine whether access can be obtained from a remote router.

Establishing and verifying a Telnet connection

If remote access can be obtained through another router, then at least one TCP/IP application can reach the remote router

A successful Telnet connection indicates that the upper-layer application functions properly.

If Telnet to one router is successful, failure to another router is likely caused by addressing, naming, or access permission problems

The next step is to use the ping command. The ping command can be used to test end-to-end connections at the network layer.

Advanced Telnet

Multiple Telnet sessions can be used and suspended by using the Ctrl+Shift+6 and x sequence.

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CCNA Sessão 2_mac_b

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