All About Networking (CCNA,CCNP R&S)

Tuesday, 27 September 2016

ATTENTION PLEASE

i regularly update all the material of CCNA later that ill update CCNP material but without your support or comment how i can understand its helpful for you or not,

so comment please if you need any type of help.

thanks.

VLAN advantages disadvantage Membership and VTP

A virtual LAN (VLAN) is a logical grouping of network devices in the same broadcast domain that can span multiple physical segments.

Advantages of VLANs:

· Increase the number of broadcast domains while reducing their size.

· Provide additional security.

· Increase the flexibility of network equipment.

· Allow a logical grouping of users by function, not location.

· Make user adds, moves, and changes easier.

Subnets and VLANs

Logically speaking, VLANs are also subnets. A subnet, or a network, is a contained broadcast domain. A broadcast that occurs in one subnet will not be forwarded, by default, to another subnet. Routers, or layer-3 devices, provide this boundary function. Switch provide this function at layer 2 by VLAN.

Scalability

VLANs provide for location independence. This flexibility makes adds, changes, and moves of networking devices a simple process. It also allows you to group people together, which also makes implementing your security policies straightforward.

IP protocols supports 500 devices per vlans.

VLAN Membership

A device's membership in a VLAN can be determined by one of two methods: static or dynamic

· Static: - you have to assign manually

· Dynamic:- Configure VTP server and it will automatically do rest

VLAN Connections

two types of connections: access links and trunks.

Access-Link Connections An access-link connection is a connection between a switch and a device with a normal Ethernet NIC, where the Ethernet frames are transmitted unaltered.

Trunk Connections trunk connections are capable of carrying traffic for multiple VLANs. Cisco supports two Ethernet trunking methods:

· Cisco's proprietary Inter Switch Link (ISL) protocol for Ethernet

· IEEE's 802.1Q, commonly referred to as dot1q for Ethernet

ISL is Cisco-proprietary trunking method that adds a 26-byte header and a 4-byte trailer to the original Ethernet frame. Cisco's 1900 switch supports only ISL

802.1Q is a standardized trunking method that inserts a four-byte field into the original Ethernet frame and recomputed the FCS. The 2950 only supports 802.1Q. 802.1Q trunks support two types of frames: tagged and untagged.

· An untagged frame does not carry any VLAN identification information in it—basically, this is a standard, unaltered Ethernet frame.

· A tagged frame contains VLAN information, and only other 802.1Q-aware devices on the trunk will be able to process this frame

Trunk Tagging

For VLANs to span across multiple switches, you obviously need to connect the switches to each other. Although it is possible to simply plug one switch into another using an Access port just as you would plug in a host or a hub, doing so kills the VLAN-spanning feature and a bunch of other useful stuff too. A switch-to-switch link must be set up as a trunk link in order for the VLAN system to work properly. A trunk link is a special connection; the key difference between an ordinary connection (an Access port) and a Trunk port is that although an Access port is only in one VLAN at a time, a Trunk port has the job of carrying traffic for all VLANs from one switch to another. Any time you connect a switch to another switch, you want to make it a trunk.

Trunking methods create the illusion that instead of a single physical connection between the two trunking devices, a separate logical connection exists for each VLAN between them. When trunking, the switch adds the source port's VLAN identifier to the frame so that the device (typically a switch) at the other end of the trunk understands what VLAN originated this frame and the destination switch can make intelligent forwarding decisions on not just the destination MAC address, but also the source VLAN identifier. Since information is added to the original Ethernet frame, normal NICs will not understand this information and will typically drop the frame. Therefore, you need to ensure that when you set up a trunk connection on a switch's interface, the device at the other end also supports the same trunking protocol and has it configured. If the device at the other end doesn't understand these modified frames or is not set up for trunking, it will, in most situations, drop them. The modification of these frames, commonly called tagging.

By default, all VLANs are permitted across a trunk link. Switch-to-Switch trunk links always require the use of a crossover cable, never a straight-through cable.

Key feature about DTP

· A trunk can be created only on a Fast Ethernet or Gigabit Ethernet connection; 10Mb Ethernet ports are not fast enough to support the increased traffic from multiple VLANs, so the commands are not available for a regular Ethernet port.

· By default, traffic from all VLANs is allowed on a trunk. You can specify which VLANs are permitted (or not) to cross a particular trunk if you have that requirement, but these functions are not covered in the CCNA exam.

· Switches (whether trunked or not) are always connected with crossover cables, not straight-through cables.

Dynamic Trunk Protocol (DTP) DTP supports five trunking modes

· On or Trunk interface always assumes the connection is a trunk, even if the remote end does not support trunking.

· Desirable the interface will generate DTP messages on the interface, but it make the assumption that the other side is not trunk-capable and will wait for a DTP message from the remote side. In this state, the interface starts as an access-link connection. If the remote side sends a DTP message, and this message indicates that trunking is compatible between the two switches, a trunk will be formed and the switch will start tagging frames on the interface. If the other side does not support trunking, the interface will remain as an access-link connection

· Auto-negotiate interface passively listens for DTP messages from the remote side and leaves the interface as an access-link connection. If the interface receives a DTP message, and the message matches trunking capabilities of the interface, then the interface will change from an access-link connection to a trunk connection and start tagging frames

· No-negotiate, interface is set as a trunk connection and will automatically tag frames with VLAN information; however, the interface will not generate DTP messages: DTP is disabled. This mode is typically used when connecting trunk connections to non-Cisco devices that don't understand Cisco's proprietary trunking protocol and thus won't understand the contents of these messages.

· Off If an interface is set to off, the interface is configured as an access link. No DTP messages are generated in this mode, nor are frames tagged.

VLAN Trunk Protocol (VTP)

VTP is a Layer 2 protocol that takes care of the steps of creating and naming VLANs on all switches in the system. We still have to set port membership to VLANs at each switch, which we can do either statically or using a VMPS. VTP works by establishing a single switch as being in charge of the VLAN information for a domain. In this case, a domain is simply a group of switches that all have the same VTP domain name. This simply puts all the switches into a common administrative group.

The VLAN Trunk Protocol (VTP) is a proprietary Cisco protocol used to share VLAN configuration information between Cisco switches on trunk connections When you are setting up VTP, you have three different modes: Server client and transparent.

Server mode—
This is the one switch that is in charge of the VLAN information for the VTP domain. You may add, delete, and change VLAN information on this switch, and doing so affects the entire VTP domain. This way, we only have to enter our VLAN information once, and the Server mode switch propagates it to all the other switches in the domain.

Client mode—
Client mode switches get VLAN information from the Server. You cannot add, delete, or change VLAN information on a Client mode switch; in fact, the commands to do so are disabled.

Transparent mode—
A Transparent mode switch is doing its own thing; it will not accept any changes to VLAN information from the Server, but it will forward those changes to other switches in the system. You can add, delete, and change VLANs—but those changes only affect the Transparent mode switch and are not sent to other switches in the domain.

VTP Messages

An advertisement request message is a VTP message a client generates. When the server responds to a client's request, it generates a subset advertisement .A summary advertisement is also generated by a switch in VTP server mode. Summary advertisements are generated every five minutes by default (300 seconds), or when a configuration change takes place on the server switch

VTP Pruning

VTP gives you a way to preserve bandwidth by configuring it to reduce the amount of broadcasts, multicasts, and unicast packets. This is called pruning. VTP pruning enabled switches sends broadcasts only to trunk links that actually must have the information.

VTP pruning is used on trunk connections to dynamically remove VLANs not active between the two switches. It requires all of the switches to be in server mode

Basic Switch configurations commands

In this article I will introduce the Cisco Internetwork Operating System (IOS) command line interface (CLI) for the 2960 series switch. You will need to logon to a switch and become familiar with the different levels of access on the switch. You will also become familiar with the commands available to you in each mode (user or privileged) and the switch help facility, history, and editing features.

User vs. Privileged Mode

User mode is indicated with the > next to the switch name. You can look at settings but can not make changes from user mode. In Privilege mode, indicated by the #, you can do anything. To get into privilege mode the keyword is enable.

HELP

To view all commands available from this mode type:?This will give you the list of all available commands for the switch in your current mode. You can also use the question mark after you have started typing a command. For example if you want to use a show command but you do not remember which one it is, use the ? as this will output all commands that you can use with the show command.

Configuration Mode

From privilege mode you can enter configuration mode by typing config term command you can exit configuration mode type type end or <CTL>+z

Configuration of Cisco 2960 Switch

To practically implement these command create a simple topology on packet tracer

Now click on any switch and configure it as given below

To know all available command on user exec mode type ? and press enter

Switch>?

Exec commands:

    [1-99]         Session number to resume

    connect        Open a terminal connection

    disconnect     Disconnect an existing network connection

    enable         Turn on privileged commands

    exit           Exit from the EXEC

    logout         Exit from the EXEC

    ping           Send echo messages

[Output is omitted]

Three command can be used to logout from terminal.

Switch>enable

Switch#disable

Switch>exit

Switch con0 is now available

Press RETURN to get started.

show version Command will display the device platform, detected interface, ios name

Switch>enable

Switch#show version

Cisco IOS Software, C2960 Software (C2960-LANBASE-M), Version

12.2(25)FX, RELEASE SOFTWARE (fc1)

Copyright (c) 1986-2005 by Cisco Systems, Inc.

Compiled Wed 12-Oct-05 22:05 by pt_team

ROM: C2960 Boot Loader (C2960-HBOOT-M) Version 12.2(25r)FX,

RELEASE SOFTWARE (fc4)

System returned to ROM by power-on

Cisco WS-C2960-24TT (RC32300) processor (revision C0) with

21039K bytes of memory.

24 FastEthernet/IEEE 802.3 interface(s)

2 Gigabit Ethernet/IEEE 802.3 interface(s)

[Output is omitted]

show mac address Command will show all detected mac address dynamically and manually

Switch#show mac-address-table

          Mac Address Table

-------------------------------------------

Vlan    Mac Address       Type        Ports

----    -----------       --------    -----

   1    0001.643a.5501    DYNAMIC     Gig1/1

To view run time configuration of RAM use show running-config command

Switch#show running-config

Building configuration...

Current configuration : 925 bytes

version 12.2

no service password-encryption

hostname Switch

[Output is omitted]

To view startup configuration [ Stored in NVRAM] use show startup-config command

Switch#show startup-config

Current configuration : 925 bytes

version 12.2

no service password-encryption

hostname Switch

[Output is omitted]

To get information about VLAN configuration use show vlan command

Switch#show vlan

VLAN Name                      Status    Ports

---- -------------------------------- --------- -----------------------

1    default                   active    Fa0/1, Fa0/2, Fa0/3, Fa0/4

                                         Fa0/5, Fa0/6, Fa0/7, Fa0/8

                                         Fa0/9, Fa0/10, Fa0/11, Fa0/12

                                         Fa0/13, Fa0/14, Fa0/15, Fa0/16

                                         Fa0/17, Fa0/18, Fa0/19, Fa0/20

                                         Fa0/21, Fa0/22, Fa0/23, Fa0/24

[Output is omitted]

show interface command will show all detected interface with their hardware description and configuration

Switch#show interfaces

FastEthernet0/1 is up, line protocol is up (connected)

  Hardware is Lance, address is 0060.2f9d.9101 (bia 0060.2f9d.9101)

  MTU 1500 bytes, BW 100000 Kbit, DLY 1000 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation ARPA, loopback not set

[Output is omitted]

interface vlan 1 is used to assign ip address and default gateway to switch. Show interface vlan 1 will give a over view of vlan1.

Switch#show interface vlan1

Vlan1 is administratively down, line protocol is down

  Hardware is CPU Interface, address is 0060.5c23.82ae

   (bia 0060.5c23.82ae)

  MTU 1500 bytes, BW 100000 Kbit, DLY 1000000 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation ARPA, loopback not set

  ARP type: ARPA, ARP Timeout 04:00:00

[Output is omitted]

delete command is used to delete all vlan configuration from switch Don’t add space between flash and vlan.dat Run this exactly shown here adding a space could erase flash entirely leaving switch blank

Switch#delete flash:vlan.dat

Delete filename [vlan.dat]?

Delete flash:/vlan.dat? [confirm]

%deleting flash:/vlan.dat

Startup configuration can be removed by erase commands

Switch#erase startup-config

Erasing the nvram filesystem will remove all configuration files!

Continue? [confirm]

[OK]

Erase of nvram: complete

%SYS-7-NV_BLOCK_INIT: Initialized the geometry of nvram

Basic Switch Configuration Step by Step

use configure terminal command to go in global configuration mode

Switch#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Now change default switch name to switch 1

Switch(config)#hostname Switch1

Set enable password to vinita and secret to nikki

Switch1(config)#enable password vinita

Switch1(config)#enable secret nikki

Set console password to vinita and enable it by login command. Order of command is important. Set password before you enable it.

Switch1(config)#line console 0

Switch1(config-line)#password vinita

Switch1(config-line)#login

Switch1(config-line)#exit

Enable 5 telnet session [ vty0 - vty4] for router and set their password to vinita

Switch1(config)#line vty 0 4

Switch1(config-line)#password vinita

Switch1(config-line)#login

Switch1(config-line)#exit

Now set switch ip address to 192.168.0.10 255.255.255.0 and default gateway to 192.168.0.5

Switch1(config)#interface vlan1

Switch1(config-if)#ip address 192.168.0.10 255.255.255.0

Switch1(config-if)#exit

Switch1(config)#ip default-gateway 192.168.0.5

Set a description finance VLAN to interface fast Ethernet 1

Switch1(config)#interface fastEthernet 0/1

Switch1(config-if)#description finance VLAN

By default switch automatically negotiate speed and duplex but you can adjust it manually

Switch1(config-if)#duplex full

%LINK-5-CHANGED: Interface FastEthernet0/1, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1,

 changed state to downSwitch1

(config-if)#duplex auto

%LINK-5-CHANGED: Interface FastEthernet0/1, changed state to up

Switch1(config-if)#duplex half

%LINK-5-CHANGED: Interface FastEthernet0/1, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1,

changed state to down

%LINK-5-CHANGED: Interface FastEthernet0/1, changed state to up

Switch1(config-if)#duplex auto

Switch1(config-if)#speed 10

Switch1(config-if)#speed 100

Switch1(config-if)#speed auto

Switch1(config-if)#exit

Switch1(config)#exit

mac address table can be wiped out by clear commands

Switch1#show

Switch1#show mac-address-table

          Mac Address Table

-------------------------------------------

Vlan    Mac Address       Type        Ports

----    -----------       --------    -----

   1    0001.643a.5501    DYNAMIC     Gig1/1

Switch1#clear mac-address-table

Switch1#clear mac-address-table ?

  dynamic  dynamic entry type

Switch1#clear mac-address-table dynamic

To restart switch use reload command [ running configuration will be erased so copy it first to startup configuration ]

Switch1#reload

Proceed with reload? [confirm]

Switch con0 is now available

Press RETURN to get started.

CCNA basic switch configuration commands sheet

Command	descriptions
switch>?	The ? works here the same as in a router Used to get the list of all available commands
switch>enable	User mode, same as a router
switch#	Privileged mode
switch#disable	Leaves privileged mode
switch>exit	Leaves user mode
switch#show version	Displays information about software and hardware.
switch#show flash:	Displays information about flash memory (will work only for the 2900/2950 series).
switch#show mac-address-table	Displays the current MAC address forwarding table .
switch#show running-config	Displays the current configuration in DRAM.
switch#show startup-config	Displays the current configuration in NVRAM.
switch#show vlan	Displays the current VLAN configuration.
switch#show interfaces	Displays the interface configuration and status of line: up/up, up/down, admin down.
switch#show interface vlan1	Displays setting of virtual interface VLAN 1, the default VLAN on the switch.
To Reset Switch Configuration
Switch#delete flash:vlan.dat	Removes the VLAN database from flash memory.
Delete filename [vlan.dat]?	Press Enter
Delete flash:vlan.dat? [confirm]	Press Enter
Switch#erase startup-config	Erases the file from NVRAM.
Switch#reload	Restarts the switch.
To Set Host Names
Switch#configure terminal	Moves to global configuration mode
Switch(config)#hostname Switch1	Creates a locally significant host name of the switch. This is the same command as the router.
Switch1(config)#
To Set Passwords
Switch(config)#enable password Vinita	Sets the enable password to vinita
Switch(config)#enable secret nikki	Sets the encrypted secret password to nikki
Switch(config)#line console 0	Enters line console mode
Switch(config-line)#login	Enables password checking
Switch(config-line)#password vinita	Sets the password to vinita
Switch(config-line)#exit	Exits line console mode
Switch(config-line)#line vty 0 4	Enters line vty mode for all five virtual ports
Switch(config-line)#login	Enables password checking
Switch(config-line)#password vinita	Sets the password to vinita
Switch(config-line)#exit	Exits line vty mode
Switch(config)#
To Set IP Addresses and Default Gateways
Switch(config)#interface vlan1	Enters the virtual interface for VLAN 1, the default VLAN on the switch
Switch(config-if)#ip address 192.168.0.10 255.255.255.0	Sets the IP address and netmask to allow for remote access to the switch
Switch(config-if)#exit
Switch(config)#ip default-gateway 192.168.0.5	Allows IP information an exit past the local network
To Set Interface Descriptions
Switch(config)#interface fastethernet 0/1	Enters interface configuration mode
Switch(config-if)#description Finance VLAN	Adds a description of the interface
To Set Duplex Operation
Switch(config)#interface fastethernet 0/1	Moves to interface configuration mode
Switch(config-if)#duplex full	Forces full-duplex operation
Switch(config-if)#duplex auto	Enables auto-duplex config
Switch(config-if)#duplex half	Forces half-duplex operation
To Set Operation Speed
Switch(config)#interface fastethernet 0/1
Switch(config-if)#speed 10	Forces 10-Mbps operation
Switch(config-if)#speed 100	Forces 100-Mbps operation
Switch(config-if)#speed auto	Enables autospeed configuration
MAC Address Table
switch#show mac address-table	Displays current MAC address forwarding table
switch#clear mac address-table	Deletes all entries from current MAC address forwarding table
switch#clear mac address-table dynamic	Deletes only dynamic entries from table