CCNA Preparation Notes By Tayyab A Sheikh
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Transcript of CCNA Preparation Notes By Tayyab A Sheikh
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PREPAIRED BY TAYYAB
CCNA Preparation Notes
Tayyab S Sheikh
1/4/2012
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NetworksPerform two tasks
- Interconnects nodes
- Establishes Communication
2 Types of Devices exist within a Network
- End Device
- Intermediate Devices
Data Networking
System Admin: Deals with End Devices, hardware / software
Network Admin: Intermediate Devices and Operating System
CCNA CCNP deal with Network Administration
Intermediate Device Vendors
Cisco, JunIPer, D-Link, Etc
Cisco operating system: Internetwork operating system or IOS
JunIPer Operating system: JunIPer operating system or Jun OS
OSI Model
Application Layer
It is there to support Applications works at the back end of applications, It Presents data to Applications.
it will differentiate between .doc and .jpg file and forward to relevant app to handle it. But apps do not
fall under this layer. i.e Http.
Presentation Layer
This layer will take data and make it uniform. In other words all data becomes same it is no longer in the
format of .jpg or .doc etc (Think encryption)
Session Layer
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The session Layer initiates, coordinates and terminates communications between applications of both
computers. It works like telephone operators who used to establish and disconnect international phone
calls in the past
Transport Layer
This layer handles Data segmentation, Flow control, Error control of sessions established between thetwo computers TCP UDP belong to this layer
1. Data Segmentation or data fragmentation
2. Flow control
3. Error Control
Network Layer
It creates logical path (virtual circuits) IP : Internet Protocol belongs to this layer, Data is converted into
Frames.
Works like a post Office. It has two main tasks:
- Sorting (routing)
- Distribution (routed)
All devices which belong to network layer is a network device i.e laptop, router, MLS (L3 switch)
Data Link LayerData packets are encoded and decoded into Bits. Physical type of transmission (i.e Wi-Fi, Ethernet, etc),
corruption of data and error detection (CRC Cyclic Redundancy Check) are handled in this layer. EMI or
Electromagnetic Interference is the main reason for data corruption. Switches belong to this layer.
Physical Layer
Data transforms into energy to transmit over any network. Only involves hardware no software is a part
of that device. I.e all cables and connectors fall under this layer. Hub
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Routing
Routing defines the best path to reach a destination. Routing can be performed in two ways static
routing and dynamic routing.
Dynamic Routing: If routing is performed by protocols such as OSPF (Open Shortest Path First), RIP
(Routing Information Protocol), EIGRP (Enhanced Interior Gateway Protocol)
Static Routing: If routing is performed by network administrator
RoutedIs always dynamic, therefore protocols are known as routed protocols. Routed protocols distribute data
across network.
General Notes:
- Bandwidth equals Link Throughput
- Data Rate ≤ Bandwidth ≤ clock rate
- Clock Rate is the Device capacity of throughput which is set by the Internet Service Provider
- Protocol = Rules and Regulations
- IP = Internet Protocol : It dictates Internet (Rules and regulations that control internet)
Note: IP and IP address are two different things. IP address is a part of IP (IP is a routed protocol, IP
address is an identifier of a network device.)
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Dynamic V.S Static
Note: IF a task is performed by the administrator it is static
If any task is performed by a protocol it is dynamic
HTTP uses TCP
Misplaces / corrupt fragments are retransmitted by TCP
MTU
: Maximum transmission Unit, size in bytes of the largest data unit (packets, frames, fragments) that can
pass through
Modes of communication (Communication Types)
1- Connection Oriented Communication
2- Connection Less Communication
Connection Oriented Communication:
- Protocol is TCP
- Sender receives acknowledgement from receive (destination)
- Reliable Communication
- Slow method of communication
- Processor intensive
Connection Less:
- Protocol is UDP
- No acknowledgement
- Fast
- Unreliable
- Uses less resources (as network is not congested with acknowledgements)
TCP and UDP
TCP: Transmission Control Protocol, i.e HTTP, etc
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UDP: User datagram protocol (Its uncontrolled), i.e Live applications, voice chat, video, audio, DHCP
Types of Network Devices
RouterRouter is a layer 3 device that can compute down to layer 1 including physical, data link and network.
Router is a unicast device. It has a database that saves the best path of each node on the network it’s
called a routing table. If a router has the destination address of destination node in its routing table
then it unicasts to the destination node. If no path is found the packet is discarded. This behavior is for
data transmission. Multicast and broadcast is used to create routing table.
A router has both LAN and WAN ports. Only routers can work in WAN topology.
Ethernet standard Speed: 10 Mbps
Fast Ethernet : 100 Mbps
Giga-net : 1000 Mbps
10 Giga : 10 000 mbps
Switch
Switch is a layer 2 device and can computer up to data link layer including physical layer. It Creates
Switching table in its data base which has possible paths to destinations. If a path is found to destination
node it is unicasted. If no path is found in switching table the switch broadcast the frame to alldestinations. Switch can broadcast and unicast
Multicast can be performed by all intelligent devices i.e layer 2 and 3 devices. This has to be done
statically.
Hub and switch can perform similar task. Depending on budget installation of hub and switch are
chosen.. Hub is the cheaper option. However switch is a lot smarter but more expensive as well.
Network layer (router) Packet
Data link (switch) Frame
Physical layer (hub) Bits
Three types of casting
- Unicast
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- Broadcast
- Multicast
Unicast- means 1 to 1 casting (communication)
Broadcast- 1 to all communication
Multicast – 1 to a specific group communication
Multicast is a parent concept of broadcast. Therefor Broadcast is a type of multicast.
MLS vs Router
MLS or router are used to establish communications between 2 networks
If the geographical distance is approx. 100m the device should be MLS. MLS can only run on LAN
standard (Ethernet – 802.3). MLS can connect two networks. It can unicast and broadcast like a switch.
Hub or switch is used for communication within network.
Decision of installing HUB or SWITCH is made on the following factors:
Hub – few users, security not an issue, low finance
Switch – inverse from hub
Difference between layer two switching and layer 3 switching Logical (IP) vs physical (mac) address:
- Layer 2 = mac address in switching table
- Layer 3 = IP address in routing table.
MLS has both switching table and routing table. On network communication is on mac address layer 2
switching is used. But between 2 networks routing table is used. MLS can be used within a network
ISP Equipment
CPE: Customer premises Equipment …. V.35 serial cable goes from your router to CPE
Switch has 24 ports
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IP addressing
Decimal to binary conversion
128 64 32 16 8 4 2 1
Binary Operators
In binary following operators apply: Or = + (add) , AND = x (multIPly), XOR = - (minus)
Input 1 Input 2 OR AND XOR
1 1 1 1 0
0 0 0 0 0
1 0 1 0 1
0 1 1 0 1
Maximum combinations in decimal
101 = 10 ( 0-9)
102 = 100 ( 00- 99)
103 = 1000 ( 000 – 99)
Binary combinations
Divide maximum number in first row into half you will get x, apply that to second row. Now take x and
divide by 2, you will get y, apply y to third and so on
22 would be 4 divide that in half you get 2 (or x) divide that in half and you get 1(that’s y)
1 0 0
1 0 1
1 1 0
1 1 1
IPv4
128 64 32 16 8 4 2 1
27 26 25 24 23 22 21 20
1 0 1 0 1 0 0 1
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10101001 binary equals 169. All you need is the table above and 1 or 0 will work as placeholder.
- There are 256 decimal numbers in an 8 bit octet starting from 0 to 255.
- An IP address is made of four 8 bit octets. i.e 192.168.0.1
- . is used as a separator between the octets 192.168.0.1 in binary would be
11000000.10101000.00000000.00000001
To make it human friendly we use decimal as it is easy to remember. But computers use binary not
decimal.
The 8 octets are divided into 2 groups the network portion of the IP address and the host portion of the
IP address.
The range of IP address is divided into 4 Classes ABC
Class Bits representing
Network
Range of
addresses
Network
Portion
Host
Portion
# of Networks
in class
# of address per
network
A 10000000 1 - 126 N.H.H.H N.H.H.H 27 = 128 224 = 16777216
B 10000000 128 - 191 N.N.H.H N.N.H.H 214 = 16384 216 = 65536
C 11000000 193- 223 N.N.N.H N.N.N.H 221 = 2097152 28 = 256
IP address format: x.x.x.x each x can vary from 0 to 255
From 0.0.0.0 to 255.255.255.255 each 1 IPv4 address will be 32bit long or 4 byte.
Octet each x is an octet. There are 4 octet in each IPv4 address.
Left to right octet 1.2.3.4
2 to the power 32 is the maximum combinations allowed
Better IP Management
Classification of IPv4 addresses
Use 1st octet of the address - 0 to 255
There are 5 classes in an IPv4
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A B C D E
A B AND C are reserved for unicast (first 3) A = Large Network B= Medium and C= small
Class D reserved for multicast and E for research and testing
A 1 to 126
B 128 to 191
C 192 to 223
D 224 to 239
E 240 to 250
Better IP Management
A 1 to 126 0 res for default Routing,
Router by default unicasts or discards. It can also be manually configured to reroute an unknown
destination to another router that will probably know the best path to destination
127 - reserved for Loop back testing. Echo message is sent after establishing a link to test this link. Echo
message can be send through the command of ping.
Source Node ↔ Destination node
1.1.1.1 is node 1, linked to 1.1.1.2 node 2, ping sends echo message from node 1 to node 2 Ping 1.1.1.2
and verity’s the link is established. In case the ping msg does not return then you either have a problem
at your side or the destination side to test yourself you use loop back testing 127.0.0.1. It does not
require you to be connected to a network. It tests the software tools to verify if everything is working.
Tcp/IP is a software with the collection of tools to communicate with other nodes and is installed by
default. Loop back testing verifies that tcp/IP is working properly.
A 1 to 126: N.H.H.H N= 8 bit, H=24 bit
B 128 to 191 N.N.H.H N=16 bit, Host = 16 bit
C 192 to 223 N.N.N.H N= 24 bit, Host = 8 Bit
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Network ID in IPv4 Address
Network id means the network portion of the IP address. Host portion is replaced by 0, when
considering network ID. Best path are defined for networks not IP addresses. i.e Routing table has
network ids or in other words network path is in routing table.
Format will be written as (x.x.x.x/network bits) i.e 10.0.0.0/8 where 8 means network has first 8 bits
If distance is less and network is the same then you use Switch
Note: IANA: Internet Assigning Number Authority
Prefix Length
x.x.x.x /y here y is prefix length. Number of network bits is subnet mask.
Subnet mask = 11111111.0000 0000.0000 0000.0000 0000.0000 0000.
255.0.0.0 is the subnet mask for class a
Every device takes
IP address AND Subnet mask = Network ID. In binary AND means multIPly
i.e 200.50.60.70 it’s a class c address
Class b = N 24 bit, H8
Subnet mask is 255.255.255.0
128 64 32 16 8 4 2 1
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Using above table to convert table IP in binary would be 11001000.00110010.00111100.01000110
subnet be 11111111.11111111.11111111.00000000
When both are multIPlied it will become. 11001000.00110010.00111100.01000110 which in decimal is
200.50.60.0/24 the “/24” shows that it is a subnet mask
Network has 200.100.50.1 . As the number of users is less therefore class c is used and each user is
assigned an IP address
Broadcast ID
Used to send msg to all hosts in the network. 200.100.50.255 will be the broadcast ID network id would
be 200.100.50.0 in-between broadcast id and network ID there are IP address. 200.100.50.1 to .50.254
Examples:
50.0.0.0/8 is class A
First IP : 50.0.0.1
Network ID: 50.0.0.0/8
Broadcast id 50.255.255.255
Last IP 50.255.255.254
50.255.255.0 is a valid IP address
172.16.0.0/16
172.16.255.255
172.1.255.0 is an IP as it is neither the broadcast id not the network id
Class A = 27 B = 214 C = 221
Host always has x -2 from total number in network
Class A IP Address
20.5.6.1 NET ID: N8, H24 20.0.0.0/8 /8 is the prefix
Broad cast ID. 20.255.255.255
First IP: 20.0.0.1
Last IP: 20.255.255.254
Subnet Mask: 255.0.0.0
2HOST BIT -2 is the formula to find host quantity
i.e 224 -2
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N.H.H.H
Where 28 is theory and practical is 27
Class A formula for number of networks is 27 -2
Class B IP Address
Range: 128 - 191
N.N.H.H: N= 16 and H = 16
130.5.6.7
Network ID: 130.5.0.0/16
Broadcast Id: 130.5.255.255
1st IP: 130.5.0.1 Last IP: 130.5.255.254
Number of Host 216 -2
Number of Networks : 214
Subnet mask 255.255.0.0
Class C IP Address
Range : 192 to 223
IP address: 192.5.5.4
Network ID: 192.5.5.0/24
Broadcast id: 192.5.5.255
Host range: 192.5.5.1 to 192.5.5.254
Subnet mask : 255.255.255.0
All of the above are class full addressing
Rules:
Both nodes on the network must have the same network ID. I .e 1.1.1.1 or 1.2.5.6
Network id will be 1.0.0.0/8 for both
WAN or LAN either case network ID must be same
Switch does not run on IP addressing
In router case LAN side will have the same network ID on both interfaces and WAN side with same
network ID but this will be different than the one used for LAN.
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Class-Less Addressing
A: 5.6.7.8 connected to 5.6.8.8 both with 5.0.0.0/8 as Network ID
B 173.9.0.5 connected to 173.9.0.6, Network ID: 173.9.00/16
C: 200.50.60.70 to 200.50.60.71, Network ID: 200.50.60.0/24
Ethernet has two types: Routed and non-Routed
Devices up to layer three have routed ports
CCNA BASIC LAB DIAGRAM:
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Link A: router to switch 1.1.1.100 fa0/0 of router
4 users 1.1.1.3, 1.1.1.2, 1.1.1.1, 1.1.1.4 starting from right then bottom then left
Link C:192.168.5.100 fa0/0 of router to switch 192.168.5.8, 192.168.5.7, 192.168.5.6, 192.168.5.1 are IP
of hosts from right, bottom, left
WAN LINK with 2.1.1.1 connected to 2.1.1.2, Network ID 2.0.0.0/8
In this case 192.168.5.100 will be gateway for C network
1.1.1.100 will be gateway for switch connected to router A on Link A
Internet:
is a network of networks.
No two networks can have the same network ID because if the ID is same then there is a chance that IP
addresses will be the same as well
.
In above scenario with 50 users you will choose a class c address you have 50 users and the remaining
204 will be wasted. Every IP address is purchased and hence cannot be wasted. A Large range of IP
addresses are wasted in class full addresses
Class less IP Addressing
Subnetting
Network portion increases and bits are borrowed from host. This concept belongs to classless IPaddressing.
Super-netting
IF you increase the host portion by borrowing bits from network then this concept is called super-
netting
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Super-netting is done to perform Route summarization: Memory management in the purpose of route
summarization
IMPORTANT
1. 192.64.32.0/24 is a Base id provided by ISP.( Base ID is an ID that you divide into subnets.)
Convert into Binary
2. 1100 0000. 0100 0000. 0010 0000. 0000 0000
3. N.N.N.H. N=24, H=8
4. 2n = N N= Number of subnets ( new branches), n= Number of bits for sub netting (increment
value in network portion)
i.e 21=2 1 bit is what you need to add 2 new subnet
5. 1100 0000. 0100 0000. 0010 0000. 0000 0000 111 1111
1100 0000. 0100 0000. 0010 0000. 1000 0000 111 1111 to get Broadcast ID
N= 25 H=7
Decimal will become: 192.64.32.0/25 192.64.32.127 x.x.x.1 to 126
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192.64.32.128/25 192.64.32.255 x.x.x.129 to 254
Broadcast of 192.64.32.0/25 will be 192.64.32.127
255.255.255.128 Subnet mask for both networks.
After Sub-netting of a Network the base id is dissolved. When subnet mask comes in class full it is called
subnet mask. In class less it is called Custom Subnet mask.
Cables
TP cable
It is used in Ethernet. Twisted Pair has a maximum throughput distance of 100 meter
Twisted pair
Twisted Pair has 2 types. UTP and STP. Unshielded and Shielded twisted pair. The foil used in STP is used
as a reflector and reduces the effect of weather. STP is used for outdoor and UTP indoor.
CAT 3
Category 3: the flexible telephone cable which comes from box to phone . Always UTP. Has 4 wires
connected to either side with a RJ11
EIA/TIA
Monitors cable standards throughout the world. Electronics industries alliance/Telecommunication
industries association
Cat 5
It is used for data: In Ethernet and fast Ethernet
Cat 6
It can support upto 10 giga Ethernet
Both cat 5 and 6 have 8 wires and RJ45 jack. Always in this sequence:
1 w/orange
2 Orange
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3 w/green
4 blue
5 w/blue
6 green
7 w/brown
8 brown
3 types of cat 5/ cat 6 cables
1. straight through
2. cross over
3. roll over/ console
Types of Twisted Pair Wires and their Color Scheme
Straight through Cross Over Roll over/console
w/orange ↔ w/orange w/orange ↔ w/green w/ orange ↔ brown
Orange ↔ orange Orange ↔ green Orange ↔ w/brown
w/green ↔ w/green w/green ↔ w/orange w/green ↔ green
Blue ↔ blue Blue ↔ blue Blue ↔ w/blue
w/blue ↔ w/blue w/blue ↔ w/blue w/blue ↔ blue
Green ↔ green Green ↔ orange Green ↔ w/gren
w/brown ↔ w/brown w/brown ↔ w/brown w/brown ↔ orange
Brown ↔ Brown Brown ↔ brown Brown ↔ w/orange
4 are used for data transfer other 4 are now being used for power supply . POE or power over Ethernet
1, 2, 3, 6 are used in data
w/orange
orange
w/green
green
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Types of Network Devices
There are 2 families of network devices:
Family one
Hub and switch
Family two
PC. Router, Mls, AP, etc
The division of families is done on the basis of electric circuits. Receive and transmit behavior is also
different.
Intra family communication uses cross over. Inter family communication will use straight through
Console cable used for configuration of router/switch which is connected into the console port of the
device
The router and Pc etc perform the following
On wire 1 and 2 they transmit, on wire3 and 6 they receive
1 Tx +ev | 2 Tx -ev
3 Rx +ev | 6 Rx –ev
Switch and Hub Family
1 and 2 receive 3 and 6 transmit
1 Rx +ev | 2Rx –ev
3 Tx +ev | 6 Tx -ev
Cisco uses Cisco xxx for its router only if it says cisco then it’s a router.
Cisco 2500 series obsolete fixed ports
Cisco 2600 obsolete here onwards its modular routers
Cisco 2800 150 000 Rps
Cisco 3600
Cisco 7200
So on
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Cisco.com under products you can find more info on each series.
There are 2 types of routers in cisco. Fixed port and modular
RS232: are the standard ports on configuration ports not for communication purpose.
Roll over with Console for local access
Basic Router Diagram
WAN Standards
HDLC
High level data link control: made by cisco is used when both routers are cisco.
Two types of Networks: Point to Point and Multi Access.
Point to Point
Is the network in which a maximum of two interfaces are connected. Two IPs one network ID
PPP protocol: Is a Point to Point protocol which is an Open standard.
Multi-access Network
In which two or more interfaces communicate with each other. Communication between one interfaces
to multiple interfaces at one given time.
Ethernet It is always Multi-access network.
Frame Relay
it is the multi-access protocol for WAN. It is an open standard. There is a frame relay switch
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There are 4 standards
HDLC – Point to Point WAN. Cisco
PPP – Point to Point, WAN. Open.
Frame Relay. Multi Access. WAN. Open. Layer 2 switching. Different branches same network.
Ethernet: Multi Access. LAN. Open
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We only need to know how to setup up to Router on our side. CPE and beyond is Service Providers
Responsibility
CPE devices can be wireless / wired
You can Have CPE cards that can be installed in a Modular Cisco Router
In any modular router there is no WAN Ports attached by default. You have to buy a separate WIC card
(WAN Interface Card).
WIC: can be 2T, 4T and 8T.
2T will have 2 WAN Ports. , 8T Will have 8 WAN Ports
Now-a-days RS232 has been integrated into USB port. DB9 to USB is a converter cable that is now used
into
RS232 has the capacity (Baud Rate is the term used in RS 232) of: 9600 always. RS232 is also known asserial.
Architecture of Cisco Devices
Memory Architecture
RAM
Read Access Memory, Volatile: The file that is made in cisco Devices RAM is called running-config.
NVRAMNonvolatile RAM (works like HD of computer). Configuration information is stored in this memory. File
made in NVRAM is Startup-config
ROM
Read only Memory, Non Volatile. Mini-IOS is installed in this memory which works like (BIOS: Basic input
output Operating System).
FLASH Memory
Operating system is in this memory IOS. Cisco 2800 and above now have flash in card which can be
replaced.
Routing table is in RAM as it is being updated at all times. When router is restarted it will delete the
routing table.
Static info and Protocol configuration is installed in NV.RAM
CLI: Command Line Interface
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GUI: Graphical Unit Interface
2 Main activities are there in CLI of cisco
Configuration Verification/Examination/Monitoring
There are multiple command prompts/Modes in Cisco IOS. Some are used for Configuring others are
used for monitoring, examination etc.
First two command prompts are reserved for verification
Modes in Router:
1 User access Mode or User Mode
Router >
Where router is the host name of the device, which is configurable. The > sign shows that it is in user
mode
The user mode has limited verification/monitoring capacity.
2. Enable/ Privilege Mode
We can completely monitor the device in this mode. You can Save, Copy or Write in this mode. We can
also del/erase in this mode
Verification has two commands: Show and Debug. These two commands can work in user mode as well.
Real-time monitoring is done by Debug whereas show command will show already gathered info.
Router#
Where # indicates that you are in privilege mode
Clock set is performed in enable mode
Carriage Return <cr> indicates that the command is now executable and there is no further
Basic cisco Router configuration
Calendar Set command will set hardware clock. Whereas clock set will set the software clock. However
hardware clock is not observed in any scenario.
3.Global Configuration Mode
R#Configure Terminal
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This mode will have a global impact on router
Ports are divided into two categories: Interface and Line.
Data communication Interface Port Configuration Line Port
R#Hostname CCNA To configure Hostname this command is used, This will make Router name to CCNA
We cannot access Startup Config and Running Config in User Mode.
Exit command will bring one step back
Show Running Config will show Running config. This has to be done in enable mode
Show Startup-config will show file in NV.RAM, permanent memory
Copy running-config startup-config will copy all values from ram to NV. Ram
Enable Password password123: Command for Enabling Password to go from user to Enable/Privilege
mode. This is known as enable password. This has to be done in Conf t
Write is alternative to copy running-conf startup-config
Disable to get out of en mode
Password can be seen in two ways in clear text and encrypted. Enable Password can now be applied and
stored in running-config and startup-config
Enable password this will show in clear text in startup-config or running-config
Enable secret will not show in clear text in startup-config or running-config
Encryption method used by cisco is MD5 Message Digest 5
User-mode password is known as login password and user-access verification
User-mode password will be placed in config t
R1 (config)#Line console 0 will take you into line configuration
R1(config-line)# password ccna123 will place a password ccna123
R1(config-line)# login will show the router that the place of asking password is at the time of login
Both password xxx and login must be done
To go back from any mode to enable mode we can press ctrl + Z keys which will take us back to enable
mode. End is an alternative to ctrl Z
NTP Network time Protocol is the protocol which will sync time throughout the network.
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Erase has two stages:
Portion or entire file.
R1# erase startup-config will erase the entire file. Reload is a must after this command
Alternatively R1# Write Erase will also erase Startup-config
R1# reload will reboot the router
R1 (Config)# enable password cisco 123 will over write any existing password.
Go to enable mode and wr to make it permanent.
R1 (config)# no enable password will erase password from running and wr will do it in startup-config.
Add no to any command where it had to be initiated i.e. en mode or config mode and it will erase it
from the running-config and wr will make it permanent.
Cisco Router Basics
WAN Link:
Physical Link and Link Configuration:
Cisco routers are not plug and play. First step is to physically link cables then step 2 is configuring it.
Whenever we have to establish a link it is done in Interface Configuration.
Connectivity of two interfaces is known as a link.
R# show intfaces will show all interfaces
R# sh int Serial0 will show the exact interface. This should be done in both Routers
Link Status Statements:
There can be 4 possibilities of outputs
1. Serial 0 is up, Line protocol is Up
2. Serial 0 is up, Line protocol is down
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3. Serial 0 is down, line protocol is down
4. Serial 0 is Administratively Down, Line protocol is Down
1. Both Link hardware and software is UP. Link up is always shown if link is up on both devices
2. No problem in Link but software is down.
3. If link is down then the software or protocol will always be down
4. Hardware stays attached and shut down interface in int config mode will show administratively
down, line protocol is down will appear.
Any kind of serial port is not hot swappable. Whereas RJ45 is
Cisco Routers by Default come with all interfaces in administratively down state.
IF one side of the link is down administratively (statement 4) or physically the other side will show
statement 3.
Statement 2:
There are three major reasons for statement 2 to appear.
1. Keep alive Not Set (10 sec by default)
2. Encapsulation Mismatch
3. Clock Rate at DCE not set
This statement 2 will show up on both ends of the link if this problem exists, when there is a problem in
the software.
Keep Alive:
If no Keep alive is received after 10 sec from destination router, it shows statement 2. Keep alive is
configurable. The keep a live interval should be same at both ends of the link.
Encapsulation Mismatch:
Occurs when 2 different protocols are running at each side of the link. One router is running PPP while
other is running HDLC
Clock Rate at DCE not set.
Clock Rate:
Clock rate limits the bandwidth of the link and is set at the service provider side. V.35 has two side one
connector of V.35 is DTE while other is called DCE
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DTE = Data Terminal Equipment
DCE = DATA communication equipment, Service provider end. Connects to CPE
DTE ↔ DCE
Bandwidth has to be configured at both DTE and DCE. While clock rate is only set at DCE. If clock rate
has not been set by service provider then it will be because of 3rd reason.
In all modular routers the interfaces are interchangeable. The sequence of differentiating one interface
from another is by Port number convention is modular router: Serial Module/Slot/Port
By default Module number start from right to left or bottom to up.
NM-16ESWMeans Ethernet Non routed, Layer 2.
FRSW Frame Relay
Ethernet
Ethernet can be routed and non-routed. The routed ones can have IPs and are used as gateways they
come factory fitted (or if they are LAN ports coming preinstalled in a router they are gateway ports or
routed ports) where as non-routed can be installed but they run at layer 2. Working as a switch
B# sh interface serial 0/0/1
This will go into S 0/0/0 and will setup there
In order to configure links we have to go into interface mode
Conf t interface serial 0/0/0 will take into interface
You can switch over into other interfaces from one interface into another from within the interface
mode
IF you want to verify clock rate and cable type following command will be used.
R# show controllers will show all interfaces adding Serial 0/0/0 will show just this interface
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Interface mode clock rate 64000 is calculated in Kbits and is configurable
Bandwidth
By default the bandwidth of 1544 Kbit is set by default in all serial interfaces.
Interface mode Bandwidth 64 will set the bandwidth on one interface
Interface mode Encapsulation xxx will change the protocol type on that interface.
Copy paste can be performed in secure crt etc
NM-1FE-TX is a single fast Ethernet port which is routed.
EnSh IP int brief will show a table with all IP related info.
Ping command
Cisco router ping command generates 5 packets which can be configured. Every packet has 100 Bytes.
Internet Control Message Protocol. ICMP is the protocol used for sending ping in cisco
RTT: Round trip time. Avg is the figure that will be RTT
In Ethernet the very first time the first Ping out of 5 is dropped
Remote Access:
Remote access must be reachable/ping-able.
Line VTY (Virtual Terminal)
VTY are used for Virtual Link, so that the communication ports can now act as a virtual Aux port. There
can be 5 (0 to 4) and above VTY Lines in each router these can be accessed through any interface.
TCP is the protocol in which the telnet tool is used to establish remote access. It is reliable as it belongs
to TCP. It establishes remote access via Line VTY.
R# telnet 1.1.1.2
But before this can be done the remote host must be enabled to accept remote host
R2# conf tline vty 0 4password xxxxx login
To switch from user mode to enable mode while accessing remotely, the password must be set at R2.
R2# conf t enable secret xxxx
R1# show line will show which of the VTY lines you are using
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Associating name to IP address
R1 (config)# IP host LHR 1.1.1.2. IP host followed by WORD followed by IP address
R1# show hosts will show the table of associated names to IP address
Ctrl + A will bring cursor to start of the written command
Ctrl + E will bring the cursor to the end
Network Design Management with CDPCDP Cisco discovery protocol is the protocol that will help obtain complete info of the network design.
Cons of CDP includes that it does not recognize non cisco devices in a network, and it cannot show
indirectly connected devices
A# show cdp neighbors: this command will show
Output:
Device ID Local Interface Hold Time Capability Platform Port ID
B S 0/0/0 127 R C2800 S 0/0//0
C Ser 0/0/1 130 R C2800 Ser 0/0/1
Destination
Port
Sh CDP Neighbors detail: will show the details
3 types of communication
Simplex, Half Duplex and Full duplex
Simplex
One sided communication receiver will only receive and always receive, same with sender.
Half Duplex
Walki Talki type communication
Duplex
telephone type
CDP uses Multicasting MAC addresses. CDP packets will be shared with neighbors. CDP packet multicasts
at 60 sec interval
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Holdtime
is the time that it waits for before removing from table.
No cdp run will disable cdp multicasting. Can be done in int level as well int uses cdp en
Boot-up Sequence of Cisco Devices
Memory is stored in Registers.
NVRAM (reg #) 0x2102
RAM: 0x2142
ROM has two registers: RX-Boot and ROM-MON
RX-BOOT 0x2101 (Mini IOS)
ROM-MON 0x2100 (Configuration, Boot up Sequence)
POST: Power on Self-Test is the process that takes place after boot up.
This checks the hardware to verify if it is working or not.
After starting the IOS has to be picked for which NVRAM is accessed. There can be 4 Configuration
Register Values for this
0x2102 0x2142 0x2101 0x2100
These 4 options do not refer to the 4 memory locations stated above.
0X2102
IF 0x2102 is there it means look in flash (This is the default sequence)
If not then TFTP server is accessed
If not then RX-boot is selected
Next Step is to Copy NVRAM to RAM
0x2142
Look in Flash
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Then TFTP
Then RX-boot
Next step it will bypass coping of NVRAM to RAM
0x2101
Look in RX-Boot (it will load mini IOS)
Next step NVRAM is copied onto RAM
0x2100
No IOS will load in this option. A Special mode will appear Configure Boot up Sequence.
Boot up sequence can be configured in global configuration
R1# Show version : IOS info details, Hardware related details, Device uptime, Current Config Register
value
Conf t config- register xxx is the command i.e 0x2101. Must be Wr after last command. This will take
effect at next reload
ROUTER (boot) > this outcome will indicate that router is in mini ios
En
Router (boot)#Erase flash will erase the flash
R1#Sh flash will show status of flash
TFTP server is used to upload IOS
Router(boot)# copy tftp flash
Will ask for host address
Will ask for file name
Will ask to erase file again
We must set the OX2102 after completing the upload in conf t# config-register 0x2102 followed by wr
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We can have multiple IOS in a device. Sequence of loading can be configured by the command:
Note: Always Ping before coping an IOS. As the first packet of the Ethernet will be dropped. In case of
ios it would copy an incomplete file.
Conf t boot system (xxx) where xxx can be flash, tftp which will set the flash 1st of tftp 1st
Conf t boot system flash xxx where xxx is source file name of the IOS to load first if there are multiple
IOS
Password Recovery1. Restart
2. Hit Ctrl +break keys before ios starts to load
Enter the 0x2100 rom-mon
3. o/r 0x2142: command will be entered to change boot-up sequence
4. I will be typed to initialize
Now you will enter a blank ios with no configs
5. go into enable modecopy startup-config running-config
6. no enable secret
7. config-register 0x2102
8. wr
9. reload
Routing
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R#Sh IP route: will show routing table
C next to a network ID shows that they are directly connected
Routing is always done on the basis of next hop
Router knows about networks through its interface and with IP address (interface local and IP of
destination). Static routing’s best practice is to use local interface for defining next hop
S shows static routes
ConvergenceCompletion of routing, each and every IP address is reachable directly or indirectly connected. Merging
networks that carry data, voice, media, etc.
Partial convergence
Some of the IPs are converged some are not
Static Routing command
R1# IP route 200.100.100.0 255.255.255.0 serial 0/0/0 will add this network statically to router 1 and
shows that the destination path is via s0/0/0
R2# IP route 200.100.50.0 255.255.255.0 1.1.1.1 will add networks path of 200.100.50.0 via IP address
1.1.1.1
IP route must be written in full no abbreviations
AD Value/ Matric is what you see with the IP address path selection
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Lower numeric value means higher value for AD
Directly connected value 0
Static routing with interface considered connected value 0
Static routing with next hop IP value 1
Metric: Criteria of selecting best path.
Best Path: Differs with each protocol
Static routing has no matric
Hop count
Entering through one interface and exit through another of 1 router will be 1 hop count
Dynamic Routing:
There are two types of Routing policies: IGP and EGP
IGP
Performs convergence within one AS
EGP
Performs convergence between two or more than two different AS
One routing protocol in one AS
Autonomous System:
A network with single routing Protocol is called an AS
A network with single administration is called an AS
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Protocols
Types of Protocols
IGP Types:
RIP: (Routing Information Protocol)
OSPF (Open Shortest Path First)
EIGRP: (Enhanced Interior gateway routing Protocol)
IS-IS: (Intermediate System to Intermediate System) Service Provider
EGP
BGP: Border Gateway Protocol
RIP
RIP is an IGP protocol
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Rip Properties:
Principle of Work: Distance Vector routing protocol
A.K.A: Bellmen Ford Algorithm
RIP Metric: Hop Count
IGP Protocol
AD Value: 120
Routing Update : Broadcast
As it is overhead router will broadcast. It usually uses unicast to send data packets
Broad cast address 255.255.255.255
It’s a Bandwidth Intensive protocol
Periodic Routing updates take place every 30 Sec
RIP is Very Easy to configure
Limitation of 15 hops RIP was made for small size networks
Does not support routing for class-less subnets.
RIP v2Multicast
Supports Routing for class-less & class-full sub netting
Multicast address: 224.0.0.9 RIP v1 and v2 will receive multicasts
R3# Sh IP protocol: will show if there are protocols running
If there are multiple protocols running the protocol with lower AD value will take preference
Conf t router RIP do sh IP route
You can run any en mode command in router conf mode with do sh
Conf t router rip network 1.0.0.0
network 3.0.0.0
200.100.50.0
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A# sh IP route
C= 3 routs directly connected
C1.0.0.0/8 is directly connected, serial 0/0/0
R 2.0.0.0/8 [120/1] via 1.1.1.2 00:00:16, serial 0/0/0
Via 3.1.1.1 00:00:25, serial 0/0/1
R200.100.100.0/24 [120/1] via 1.1.1.2 time, s 0/0/0
R200.200.100.150.0/ 24 [120/1] via 3.1.1.1, time, ser 0/0/1
RIP 2 can replace RIP1, there is no need to remove RIP before installing RIP2
RIP v1: Send: v1 Receive: V1&V2
RIPv2:Send V2 Receive V2
When there is a mix of RIPv1 and RIPv2 it will be partially converged
Conf t router RIPversion 2: is the command to
240 seconds is the hold time in RIP before it removed entries from routing table if the destination is not
reachable. However after 30 sec it will stop forwarding packets to the destination
Enclear IP route * will remove routing table entries which are not actively sending packets. It will
refresh routing table
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R1#
C1.0.0.0/8 is directly connected, s0/0/0
C 4.0.0.0/8 is directly connected, serial 0/0/1
C200.100.50.0/24 is directly connected, fast Ethernet 0/0
R 200.100.100.0/24 [120/1] via 1.1.1.2 s0/0
R 200.100.200.100/24 [120//1] via 4.1.1.1 s0/1
R3.0.0.0/8 [120/1] via 4.1.1.1 s0/0/1
Via 200.100.20.2 fa0/0
OSPF
OSPF Configuration:
1. Process ID
2. Wildcard mask
3. Area ID
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When 2 AS converge at one router Redistribution has to take place
If 2 AS converge with a link then BGP is used
Wildcard mask:
Host bits, It is inverse of subnet mask.
It’s the difference between the starting and ending of the range i.e .0 - .255
Process ID
Is only important when there are multiple AS running on a single router.
Process ID differentiates different routing systems on a single router
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Process ID is only significant for one router.
R1#conf t router ospf 1 net 1.0.0.0 0.255.255.255 area 5 End
EIGRPIt is a balanced hybrid routing protocol
Hybrid of RIP and OSPF
Cisco designed EIGRP
As it is Cisco Propriety, and does not work on any other vendor
IGP
AD value =90
Multicast address: 224.0.0.10
- Incremental and triggered multicasts take place
Supports both class-less and class-full, class full does not require wild card mask whereas calss-less does
Metric: Composite Metric
1. Bandwidth
2. Delay
3. Reliabil ity
4. Load
5. MTU
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EIGRP is by default set to consider Bandwidth and Delay combination
EIGRP Metric = (107/minimum Bandwidth)256 +(total delay)256
Units of the above formula bandwidth is calculated in Kbps
In the above pic the top path has 1.5mb as the minimum bandwidth
Bottom path has 10mb so bottom is the better path
256 is multiplied so that the minute differences between the path now become noticeable
Delay in above formula calculated in 10 of micro sec: 1 x 10-6 of a sec
Tables:
1. Neighbor Table (works same as OSPF hello sent, etc.)
2. Database table (has two paths best and second best)
3. Routing table (Best Path, when best path goes down the second best takes place)
EIGRP supports large to very large networks
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Divisions is
Autonomous system numbers are assigned by AIANA like IP.
EIGRP uses ASN whereas OSPF uses Process ID, however unlike Process ID the ASN must be same
throughout the AS
#conf t router eigrp do sh IP route network 1.0.0.0end
IP traffic Management / Network Security
ACLStandard and extended (both can be configured inbound and outbound)
Standard
Source IP Based / Network ID
Extended
IP/Network ID Destination IP/ Network, Protocol /Port
Defining an ACL
Making a List in which allow or deny should also be applied
ACL must be defined in Global mode of router or switches
Implementation can be applied on Interfaces, Lines, Processes (just like routing protocol) i.e NAT
List of ACL that can be made
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On 1 router or switch the standard number of ACL that can be configured is 99 however this range has
expanded
1 to 99 is Standard 100 and above will not be standard (Source IP)
Extended gives another 100 from 100 to 199 . (Source, Destination, Protocol)
Each ACL list can have unlimited number of restrictions or permissions
Task Block 200.100.50.1 not to reach 200.100.100.1
1. We will define the ACL at A
2. We will apply on A at fa0/0, inbound
# Sh access-lists to verify
A (config) #access-list 5 Deny 200.100.50.1 0.0.0.0 in
A single IPs wildcard mask will always be 0.0.0.0 Wild card mask can be of a single IP as well as network.
Rule of thumb is that you block at the very start of Network so that it does not utilize network
bandwidth
Rules of Wildcard Mask
Must start at Network ID and end at Broadcast ID check the table below
So on 128 64 32 16 8 4 2 1
0-63 0-31 0-15 0-7 0-3 0-1
64-127 32-63 16-31 8-15 4-7 2-3
128-191 64-95 32-47 16-23 8-11 4-5
192-255 96-127 48-63 24-31 12-15 6-7
128-160 64-79 32-39 16-19 8-9
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If it does not fall in the table above it cannot be a wildcard mask i.e if a range starts from x.x.50.2 and
ends at x.x.50.5 it cannot exist as it does not fall in any category above
i.e x.x.50.0 to x.x.50.11 in which case there will be a split from 0-7 and 8-11 which comes from the two
tables above
Look at the table groups, take any table and minus 1 which will be the only wildcard mask ranges i.e.
x.x.x.3 , x.x.x.7, x.x.x.15, x.x.x.31 can be the only ranges.
(Config)# access-list 5 permit 1.1.1.1 0.0.0.0
(config)# access-list 5 deny 1.1.1.1 0.0.0.0
ACL rule: If the above is written in an ACL, whatever is written first in line is executed
# conf t access-list 5 deny 200.100.50.4 0.0.0.0
The above command is incomplete and will block all addresses including the one stated above as by
default ACL has a line defined which Access-list 5 is deny any
To counter this line must be written
# conf t access-list 5 permit any
# conf t access-list 6 permit 200.100.50.4 0.0.0.3
Which will allow x.x .50.4 and the next 3 x.x.50.5, x.x.50.6, x.x.50.7
Example
Have to deny x.x.50.5 to x.x.50.7
#conf t access-list 7 deny 200.100.50.6 0.0.0.1
#conf t access-list 7 deny 200.100.50.5 0.0.0.0
#conf t access-list 7 permit any
Another way of doing the same
#conf t access-list 8 permit 200.100.50.4 0.0.0.0
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#conf t access-list 8 deny 200.100.50.4 0.0.0.3
#conf t access-list 8 permit any.
The above will permit the first address which has been written first and the remaining will be denied
In ACL any 1 line cannot be removed the entire ACL has to be removed. Using notepad in this scenario
helps copy old ACL edit it and after removing old ACL from running config past the new one from
notepad
#show access-list
Will show if there are any access lists available
#conf t access-list 8 deny 200.100.50.4 0.0.0.0
#conf t access-list 8 permit any.
#Conf tint s0/0/0IP access-group 8 outend sh access-list
Note:
#conf t access-list 8 deny 200.100.50.4 0.0.0.0
&
#conf t access-list 8 deny host 200.100.50.4
Are interchangeable for single IP
Extended ACL
#conf taccess-list 105 deny (parent protocol) (source IP with wildcard) (destination IP with wildcard)
eq (name or port number)
#conf t access-list 105 deny tcp 200.100.4 0.0.0.0 200.100.100.100 0.0.0.0 eq telnet (eq 23)
Alternatively: #conf t access-list 105 deny tcp host 200.100.4 host 200.100.100.100 eq telnet (eq 23)
# access-list 105 permit IP any any
As by default it will deny IP any any ( any source to any destination)
#Conf tint s0/0/0IP access-group 105 outend sh access-list
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Assignment
To block ping command is
# access-list 103 deny ICMP (source IP) (destination IP ) echo
Group A 200.100.100.100 telnet deny
Group B Group C ping deny
Solution to above problem:
# conf t access-list 107 deny tcp 200.100.50.8 0.0.0.3 host 200.100.100.100 eq 23
# conf t access-list 107 deny ICMP 200.100.50.2 0.0.0.1 200.100.100.4 0.0.0.1 echo
# conf t access-list 107 permit IP any any
# conf t int s0/0 IP access-group 107 in/out
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New assignment
Group B should not be able to http with the web server
Types of IPsPublic and Private
Public
Is Paid while private is not paid
Private
Unpaid. Free for all to use in their private networks cannot access internet with these IPs
Class A: 10.0.0.0/8 to 10.255.255.255
Class B: 172.16.0.0/16 to 172.17.0.0/16
172.17.x.x , 172.18.x.x all the way to 172.31.x.x
Class C: 192.168.0.0/24
Public IPs are usually configured on WAN interfaces
NAT
NAT (Network address Translate), Which translates the private IP into the public IP provided by the ISP
Communication on internet can only be performed by public IP
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In addition to the source address an additional port number is added to the header of the packet. This
informs the destination node that there are multiple source nodes at the source IP. And returns the
packet with the same header.
When the packet is received by the NAT server it looks up the port number and returns the packet to the
destination node on its local network.
NAT
private address is translated into public IP and sent to the destination node along with a port number
assigned to the local node the source node
PAT
Public to private translation takes place when the packet is received from internet and forwarded to the
node on the local network
Public is also known as global, private AKA local
Static NAT vs Dynamic NATStep 1 of NAT Configuration
Defining Inside and Outside interface of the router
There Are two types of public IPs: Static and Dynamic
Dynamic changes
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Static remains same
Static Public IP has static NAT and dynamic Public IP has Dynamic NAT
#debug IP packet
This will show all inbound and outbound packets at the router
# U all
This will stop all debugging
#conf t Int fa 0/0 IP nat insideint s0/0/0 IP nat outside exit
#conf t IP nat inside source static 200.100.50.4 1.1.1.1 :can only work where the IP address will
remain static and if the number of IPs to be advertised is low
# show IP nat translations : will show nat translations
NAT is Important for better IP management as well as security
#conf t access-list 11 permit 200.100.50.4 0.0.0.3
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# conf tIP nat inside source list 11 interface serial 0/0/0 overload
Overload will implement pat
Switching
L7 L2 L2 L3 L2 L2 L7
L1 L1 L1 L1 L1 L1
An Other way is
IP MAC MAC IP MAC MAC IP
Bit Bit Bit Bit Bit Bit
MAC address
At Layer 2
Media Access Control Addresses always belongs to an Ethernet Port. A Serial port never has MAC
address
MAC cannot be changed, It is in Hexadecimal form
Hexadecimal is 1 to 9, A to F. where F = 15 and total numbers start from 0 therefore 16 digit
It’s a 4 Bit Format
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1 hexadecimal = 4 bits
1 MAC Address = 12 Hexadecimal or 48 bits, or 6 Bytes
FORMAT used:
8FC9.ABCD.0157
8F-C9-AB-CD-01-57 Byte by Byte division
8FC9ABCD0157
Front End: IP back end :MAC
ARP
Address Resolution Protocol is the protocol that helps generate ARP table which has mac address and IP
address. It is a Layer 3 table. ARP request and ARP reply are both Broadcasted. The aging timer is set to 4
Hours in Cisco. It is configurable
There are two types of table. Prebuilt and On demand.
Routing table is Prebuilt. ARP is on demand. It only starts looking for IP/mac maps when a request
occurs.
ARP is not the same as Switching
Switching table is also known as MAC Address Table.
Cisco Switch
24 Port – Number start from 1 to 24
48 Port – 1 to 48
Switch start from Fast Ethernet, It is considered to be a module there for it has interfaces like fa 0/1 to
0/24 or 0/48
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All ports on a switch are non-routed ports AKA switch port.
Sw# show mac-address-table
To save time instead of writing full mac address we will use A B C D for this example
A sends packet to D. Switch records that A is on port 0/5 then it broadcasts to all other ports and D will
reply.
Switch does not broadcast for D lookup on 0/5 as it already knows that this port is linked to A. Once it
knows the Mac address and its Ports it will start unicasting to known addresses.
This table remains empty until communication starts.
MAC Port #
A 0/5
D 0/15
Mac address table aging time is 5 mins / 300 secs
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Cisco Switches known as Catalyst. It’s Layer 2 and multi-Layer both come under catalyst. Console port
identifies if the switch is manageable or not.
Cisco switch Ports are also known as Non-routed or switch ports. IOS recognizes switch port
Switch Port
Has two types. Access port and trunk port
Interfaces on Cisco Switches are by default set to up state.
By default all ports are set as access port.
Access ports
are ports that are connected to an end user/single user or host. i.e printer, camera, computer. and the
link is known as access link
Trunk Port
A port that connects switch to another switch. And the link is known as a trunk link.
Any of the 24/48 ports can be used as access ports or trunk ports.
An access link can change into a trunk link dynamically and statically depending on the model of the
catalyst. i.e
2950 and 2960 Layer two switches
3550 , 3560, 3750 ……. And higher series are Multilayer switches. Among all these 3550 series is the only
switch model that dynamically converts an access port into a trunk port. As long as one of the switches
in 3550.
Configuration of trunk links
Trunk: Dynamic and Static
In labs static is the only switching we will be asked for.
Encapsulation is configured in non-routed trunk ports
Static:
- Encapsulation : ISL (inter Switch Link)(Cisco Proprietary)
802.1Q AKA Dot1Q (IEEE)
- Switch Port Mode: Trunk
Access
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Dynamic:
- Encapsulation : ISL (inter Switch Link, Cisco Proprietary)
802.1Q AKA Dot1Q (IEEE, Open standard)
- Switch Port Mode DTP protocol is used (Dynamic trucking protocol, cisco proprietary)
Switch Port mode has two types in dynamic switching: Dynamic Desirable and Dynamic Auto
DTP session establishment means trunk link has been established.
It has two requirements: DTP request and DTP reply after which a DTP session is established
Dynamic Desirable: Can generate both DTP request and DTP reply
Dynamic Auto: can only generate DTP reply.
Dynamic Desirable and Dynamic Auto are configurable and one can be changed into the other
In short you require at least 1 DD among the two switches to establish a DTP session.
Catalyst 3550 by default is set to Dynamic Desirable all others are set to Dynamic Auto.
1 Network ID is also a network domain
All broadcast ids have 1 mac address which is FFFF.FFFF.FFFF
VLAN
VLAN stands for Virtual Local Area Network. It is a logical partition that isolates different broadcast
domains.
VLAN is a broadcast Domain. The # of networks is the # of broadcast domains. 1 VLAN = 1 Broadcast
domain = 1
We can configure 1 to 4094 on a single switch
Steps to setup VLAN
1. Defining VLAN
2. Port association with VLAN
VLAN tag isolates 1 network with other networks on the same switch.
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VLAN 1 is set on every catalyst by Default
VLAN 100 : Port 1 to 4 has 10.0.0.0/8 broadcast domain
VLAN 200: Port 11, 13,16,19 is 20.0.0.0/8
VLAN 300: Port 21,223, 24
VLAN 100 tag is replaced by Mac address. When frames come into switch via interface VLAN tag is
added to the frame when it exits the switch the VLAN tag is removed.
1 Broadcast domain should be in 1 VLAN
All switches should have identical VLANS
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When a computer sends a frame to the switch the packet header is imposed with a VLAN tag.
I.e frame comes in from port 7 the switch looks at which ports belong to VLAN 200 locally and forwards
to all VLAN 200 ports on local switch then it looks for a trunk port if the switch has a trunk port it will
forward the frame to switch 2 the switch 2 looks for VLAN 200 ports and forwards again to these ports.
The VLAN tag is taken off at the communication port before sending it to the host connected to thisport.
If a port is not defined by the user in any defined VLANs then it is a member of VLAN 1 which is the
default VLAN
NOTE:
Access Port: Is a port that is in one VLAN and it handles communication of that particular VLAN and only
of that VLAN. It cannot be in two VLANS. If a switch port is a member of a VLAN then that is an Access
Port.
Access Port: Enter VLAN tag imposed on frame
Exit VLAN tag removed on frame
TRUNK Port: Enter No change in frame header
Exit No change in frame
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VTP:
Cisco proprietary, It is a protocol that dynamically propagates network. Defining VLAN on one switch will
define switches on all switches
VTP domain
Is a group of switches that shares common identical VLAN database.
VTP Mode/ VTP operational Mode
Choses which switch should be selected to propagate the network
Three VTP operation modes: Server, Client, Transparent.
By default every cisco switch has server mode selected by default..
Differences between SERVER CLIENT and TRANSPARENT
SERVER Mode CLIENT Mode Transparent Mode
Create VLAN Cannot Create VLAN Create VLAN
Delete VLAN Cannot Delete VLAN Delete VLAN. But only those
VLANs that are created in
Transparent Mode
Modify VLAN Cannot Modify VLAN Modify VLAN. But only those
that are created in transparent
Mode
Transmit VLAN database Can transmit VLAN Transmit VLAN but only those
that are received by other
switches
Receive VLAN database Can Receive VLAN database Receive VLAN database
Receives, Copies (sync),Forwards (transmits). Database
it receives
Receives, Copies (sync),Forwards (transmits). Database it
receives
Receives and transmits but doesnot keep a copy (sync). DOES
NOT SYNC
Transparent Mode
It Is implemented for security purpose. i.e if you want two new VLANs that should not be propagated
throughout the network, it will be created in this mode. it will keep these VLANS hidden from other
switches in the network.
Having 2 VLANs of a single switch being connected by a router is not an efficient or scalable option.
Concept: Inter VLAN routing with a Router on a Stick.
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In order to have one link that connects to the switch we will create 2 logical interfaces in one interface.
Cisco Routers only support Dot1Q encapsulation. Cisco switches have both Dot1Q and ISL encapsulation
Cisco routers do not support DTP and has to be connected statically to the switch
Configuration Commands
Configuration Sequence:
1. Trunk
2. VTP
3. VLAN
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#sh interfaces trunk : will show the existing trunks
# conf t ho SWA
# conf t int fa 0/8 switchport trunk encapsulation dot1qswitchport mode trunk (?)
Same on the other switch
VTP:#sh vtp status
# vtp domain Cisco : changes the name
All commands of VTP are executed in Global mode
#vtp mode client: changes mode to client from default
# sh VLAN : will show VLAN database, trunk ports are invisible
In addition to VLAN 1 there are 4 other VLAN that are there by Default these 4 cannot be used as they
are reserved for switch cpu usage 1002 ,1003, 1004, 1005 are the 4 VLANs
# conf tVLAN 100 name HR exit
# conf t VLAN 200 name IT exit
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# Conf t int fa0/2 switchport access VLAN 100 : will make 0/2 a member of VLAN 100
Router can be connected to wither router in our scenario
VLAN config steps
Step 1: configure IP address and default gateway on end devices
Step 2: Configure VLAN and access ports.
Step 3: no sh command on Router’s physical interface
Step 4: Configure Trunk Link RS . It must be configured statically and dot1q encapsulation enabled
Step 5: Configure sub interfaces on router
- VLAN membership (association)
- Encapsulation of dot1q
- IP configuration sub interface
Step 6: Verify that VLANs are communicating to each other
Enable no shut on router
Enable trunk on switch just like we did above
R# en conf t int fa 0/0. 100: will make a sub interface
R# en conf t int fa 0/0 100 encapsulation dot1q 100
R# en conf t int fa 0/0 100 IP address 200.100.20.100 255.255.255.0
IP address are assigned at the very last
R# sh IP route will show both sub interfaces
Multi Access Networks
Frame Relay Switching
Frame relay is a WAN technology that connects multiple branches that are connected in a manner that
they give a feel of directly connected branches.
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It works just like Ethernet but it is used for WAN and instead of
DLCI
Data link Circuit Identifier, works just like mac in Ethernet but this is for Frame Relay
On each switch there are multiple DLCI which are simple numbers.
Frame Relay switch is on the service provider’s side
DCE should always be on the service provider side
Frame relay switches are actually routers which are acting as switches for Frame relay and other wise
work upto Layer 3
Frame relay is an example of VPN
To communicate between R1 and R2 a Virtual tunnel is made at the Frame Relay switch that will
forward it to the interface that is connected to router 2.
This virtual circuit has to be configured. This virtual circuit is called PVC.
To connect every two branches we require at least 1 PVC connection
Ethernet is a Broadcast Multi-access while Frame relay is a NBMA non Broadcast Multi Access topology
Each PVC is identified by DLCI.
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When R1 sends a packet top R2 it attaches a tag with the packet i.e 102 DLCI which is the DLCI for PVC
leading to R2
IP to DLCI mapping can be performed statically and Dynamically, Inverse ARP is the protocol used to
dynamically map DLCI
Dynamic mapping is process intensive and is not preferred when bandwidth is an issue.
Commands
# Conf t frame relay Switching
# Conf t frame relay Switchingint ser 2/0 no IP address
No IP address command makes sure there is no IP assigned
# Conf t frame relay Switchingint ser 2/0 encapsulate frame-relay
Next step clock rate
# Conf t frame relay Switchingint ser 2/0 frame-relay intf-type dce
The above command will change its own type to dce if cable is connected wrongly, this can only change
its type in frame relay
# Conf t frame relay Switchingint ser 2/0Clock rate 64000
# Conf t frame relay Switchingint ser 2/1 frame-relay route 102 interface serial 2/1 201 no sh
Which will create a PVC at 102 at 2/0 and destination is 2/1 with DLCI 201
# Show frame-relay route
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Will show output of PVC
# Conf t frame relay Switchingint ser 2/1 no IP addressencapsulate frame-relay frame-
relay route 201 interface serial 2/0 102 no sh
Will go back to router 1. In interface will apply IP address and the
# conf t int s2/0 IP address 1.1.1.1 255.0.0.0 encapsulation frame-relay no sh
Inverse ARP will become active is the above scenario
On client side verification is done by
# Show frame-relay map
STATIC routing
R1# conf t int ser 2/0 shutdown end
Which will shut down the interface and the map will be deleted
R1# conf t int ser 2/0 no frame-relay inverse-arp
Which will shut down inverse arp which is on by default
R1# conf t int ser 2/0 no frame-relay inverse-arp frame-relay IP address 1.1.1.2 102 no sh
Our IP and Destination DLCI
R2# conf t int ser 2/0 no frame-relay inverse-arp frame-relay IP address 1.1.1.1 201 no sh
IPv6
Intro to IPv6
128 bits long
IPv6 address are assigned in hexadecimal numbers, 32 hexadecimals in one address, which is divided
into 8 groups
0 to 9 then A to 16. A is 10, B is 11 and so on
U hexa = 4 bits
1 IPv6 address has 32 hexadecimal
16 bytes
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: is used to separate group just like . was used to separate auctits
i.e AB01 : 56789 : 9FEE : CBE9 : CBF8 : 8CC9 : 9315 : 8EEF
00AB:0000:0000:000E:0000:0000:0000:0100
AB:0:0:E:0:0:0:100, AB:0:0:E::100
:: CAN BE USED ONLY ONCE IN IPv6 ADDRESS
200B : 0000 : 0000 : 000E : 0000 : 0000 : 0000 : 0500 WHICH CAN BE WRITTEN AS
200B : 0 : 0 : E : 0 : 0 : 0 : 500
PrincIPle of IPV6:
Adjacent 0 groups in an IPv6 address can be replaced by :: (double colleen ), But this can happen only
once in an IPv6 address.
In the above example we should implement the rule after E as we can reduce 3 groups therefore making
it shorter
200B : 0 : 0 : E : : 500 making groups 5
There are no classless address
Size of network is fixed in IPv6.
No Class exist for large medium or small size organizations
Network has 64 Bits and interface has 64 bits. It can support sub netting however it is not performed at
the time neither is it considered
200B : 1 : 2 : 3 : 4: 5 : 6 : 7
Where 200B : 1: 2 : 3 is Network ID and Interface ID is 4 : 5 : 6 : 7
The network address will be represented by 200B :1:2:3 : : /64 where Interface group will be :: as all will
be 0.
There is no Broadcast ID in IPv6 as it does not support Broadcasting it is multicast.
Link Local Address behaves like broadcast ID as there was a need for having an address that can replace
broadcast
2009: 0 : 0 : 0 : 0 : 0 :0 : 0
2009 ::/64 is the same thing
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Types of IPv6 addresses
1. Global Unicast addresses (Public IPs)
2. Site Local Address (Private IPs)
3. Link Local Address (broadcast ID replacement, calculated from MAC)
4. Multicast Address (Multicast Address)
Global Unicast Address:
They are configurable, and routable, Public IPS
Site local Address: They are configurable and routable, Private IPs
Link Local Address: They are not configurable. Calculated from MAC address
Multicast: They are configurable and routable.
Each Hexadecimal has 4 bits
8 4 2 1 (4 bits)
1 0 1 0 A which has value of 10
First digit of the first group of Hexadecimal address decides if it is a global address
001x will mean it is a global address. In other words if the hexa address starts with 2 or 3 it is a global
address. But for the time being the address starting with 2 will be a global unicast address.
/3 is usually seen with global unicast address however this is shown to say that the first 3 bits have been
checked and it is verified to be global unicast this is not in any way representing subnet mask
Site LocalIf the first group of the hexa address is FEC0 it is a site local address.
F:1111 E:1110 C:1100 0:0000
If the first 10 bits of a Group are 1111 1110 11 then it is a Site Local therefore
FECx , FEDx, FEEx, FEFx ALL WILL BE SITE LOCAL
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/10 show site local address again this is to show that it is a site local address and has nothing to do with
subnet mask.
Link LocalFE80 is a group that represents link local address. We look at the first 10 bits
F:1111 E:1110 8:1000 0:0000
IF the first 10 bits are 1111 1110 10
FE8x, FE9x, FEAx, FEBx. All represent Link Local
Multicast Address
If the first 8 bits are 1111 1111 then it is a multicast address. In other words if the first group starts with
FF it is a multicast address.
/8 suggests that the first 8 bits are important.
ANY CAST
It has multiple servers all with the same unicast address all having the copied databases. The closest
server is chosen when a user tries to access data however the changes take effect in all servers
IN CISCO INSTEAD OF IP WRITE IPv6 in all commands and verifications
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# conf tint fast Ethernet 0/0IPv6 en IPv6 address 2001::a/64no sh no keepaliveend
Ping IPv6 200a:b:c:d::b
Alternatively ping 200a:b:c:d::b can also be seen in
IPv6 convergence:
Static routing:
R1# conf t IPv6 route 2002::/64 200a:b:c:d::b end
R1# sh IPv6 route
RIPng is used in IPv6 routing
RIP next generation
(RIP metric + 1 is the RIPng metric) The hop count is started when the packet leaves the router whereas
RIP calculated a hop when it crossed a router
Before enabling routing protocols on IPv6 we must enable IPv6 first
By default IPv6 and IPv4 multicast is not enabled
R1# conf t
IPv6 unicast- routing
R1# conf t int ser 2/0 IPv6 rIP word enable
where word is the name of the tracking id and it must remain same throughout the AS.works just like
ospf routing id
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R1# conf t int fa 0/0 IPv6 rIP word enable
R1# conf t IPv6 router rIP word this will take you into rIP area where changes can be make i.e
redistribution or route-map is placed
OSPFv3 is used in IPv6
In OSPFv3 the router ID is always a IPv4 address never a IPv6 address. Best thing is to hard code an IPv4
router ID
R2# conf t IPv6 unicast- routing
R2# IPv6 router ospf 1 router-id 2.2.2.2 exit
R2# int ser 2/0 IPv6 ospf 1 area 0 end
Redistribution:
R2# conf t IPv6 router ospf 1 redistribute rIP word
R2# conf tIPv6 router rIP word redistribute ospf 1 metric 1