ELLIOT'S CISCO NOTES

for future reference by me for me

these are very unorganized!!!! dont feel like retyping them


lesson 3

network protocol overview


network communications protocol

allows two or more devices to communicate over one or more networks.

examples include ip, tcp, http


network security protocols

secures data to provide authentication, integrity, and encryption

examples include ssh, ssl, tsl


routing protocols

allows routers to exchange route information, compare it, and select the quickest option availible

examples include ospf, bgp


service discovery protocol

used for the automatic detection of devices or services

examples include dhcp, dns


general terms

network protocol suite

a group of inter related protocols necessary to perform a communication function

open standard protocol suite

freely available, can be used by any vendor on their hardware

standards based protocol suite

endorsed by the networking industry, and approved by a standards organization. insures that products from different origin can interoperate


tcp/ip layers

4 - application: represents data to users, plus encoding and dialog control

3 - transport: supports communication between various devices across diverse networks

2 - internet: determines the best path through the network

1 - network access: controls the hardware devices and media that make up the network


tcp/ip layers examples

(// means subcategory, //// means item in said subcategory)

application layer

// name system

////DNS [domain name system]

*

// host config

//// dhcpv4

//// dhcpv6

//// slaac

*

// email

//// smtp

//// pop3

//// imap

*

// file transfer

//// ftp [file transfer protocol]

//// sftp

//// tftp

*

// web and web service

//// http

//// https

//// rest


transport layer

// connection

//// tcp

*

// connectionless

//// udp


internet layer

// internet protocol

//// ipv4

//// ipv6

//// nat

*

// messaging

//// icmpv4

//// icmpv6

//// icmpv6 nd

*

// routing protocols

//// ospf

//// eigrp

//// bgp


network access layer

// address resolution

//// arp

*

// data link protocols

//// ethernet

//// wlan


application -> transport -> internet -> network access

content layer -> rules layer -> physical layer

computer receiving: ethernet -> ip -> tcp -> data

computer encapsulating: data -> tcp -> ip -> ethernet


osi model layers

7 - application: contains protocols used for process-to-process communications

6 - presentation: provides representaions of data being transferred between the application layer

5 - session: provides services to the presentation layer to organize its data exchange

4 - transport: defines services to segment, transfer, and reassemble data between end devices

3 - network: exchanges individual pieces of data over the network between end devices

2 - data link: describes methods for exchanging data frames between devices over a common media

1 - physical: decribes the mechanical, electrical, functional, and procedural means to activate, maintain, and de-activate physical connections for a bit transmission to and from a network device


ip addresses

there are two parts to an ip address: the network and host portion

network portion[prefix]: the left most part of the address. indicates what network the device is on. all devices on the same network have the same network portion,

host portion[interface id]: remaining part of the address. identifies a specific device on the network. this portion is unique to each device.

example: 123.456.7.890

123.456.7. is the network portion

890 is the host portion

subnet mask divides the 2

mac versus ip

mac: identifies devices locally

ip: identifies devices globally


enable secret: gives extra security to enable password

enable password: priv exec mode, global ect



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