Cisco

Front 1

Location of the Cisco IOS

IOS stored in Flash

IOS copied from flash to volatile RAM - where it runs during normal operation

Back 1

Access Methods (Telnet, SSH & Console)

Allows configuration commands to be entered (Console)

Content is sent in clear text (Telnet)

Use to keep user ID, passwords & session content encrypted (SSH)

Front 2

Purpose of Converging Networks

The purpose of a converged network infrastructure:

reduces the cost of deploying and maintaining the communication infrastructure

Back 2

Hot Keys and Shortcuts

Ctrl-z : Exits config mode & returns to privileged EXEC

Ctrl-shift-6 : Allows the user to interrupt an IOS process such as ping or trace route

Ctrl-c : Aborts the current command & exits the config mode

Tab : Completes the remainder of a partially typed command or keyword

Front 3

Device Names

Contain no spaces

Be less than 64 characters in length

Back 3

Securing User EXEC Access

Console port must be secured

Vty lines allow access to a Cisco Device via telnet

Front 4

Configuration Files

Startup config is removed using the erase startup-config command

The configuration file saved in NVRAM will be loaded when the device is restarted

Back 4

Configuring a Switch

IP address - together with a subnet mask, uniquely identifies end device on internetwork

Subnet mask - determines which part of a larger network is used by an IP address

Interface Vlan1 - allows remote management of a layer 2 switch

No shutdown - administratively enables the interface

Front 5

Test the Loopback Address on an End Device

Pinging the local host confirms that TCP is installed & working on the local network adapter

Back 5

Protocol Data Units (PDUs)

A PDU is a general term used to describe a piece of data at any layer of a networking modes

1. Frame Header 2. Network Header 3. Transport Header 4. Data 5. Frame Trailer

Front 6

Network Addresses & Data Link addresses

Network Address ( Unique host address at the Network or Internet layer )

-These addresses are also known as logical addresses

Data Link Address

-Destination data link or MAC address

-Used by NICs to decide whether to accept a frame

ARP (Address Resolution Protocol) uses a broadcast to discover the AMC or Data Link address of a host given its IP address

Back 6

Intermediary devices interconnect end devices

Functions:

-Regenerate and retransmit data signals

- Apply security settings (Permit or Deny) to control the flow of data

-Notify other devices when errors occur

Front 7

Providing (QoS)

The network provides the ability to prioritize traffic. It can provide predictable levels of service to different traffic types.

Time-sensitive communication -increase priority for services like telephony

High importance to organization - increase priority for production control or business financial transaction of data

Non time-sensitive communication - decrease priority for web page retrieval or email

Back 7

Default Gateway

What would be the effect of a default gateway being incorrectly configured on a host?

-The computers can converse with other computers on the local network, but are unable to with computers on remote networks.

Front 8

Connecting Remote Users

-DSL (Digital Subscriber Line) : Internet through phone line. Highspeed, always on, splits your access line into three signals: phone, upload data, download data

-Dialup : Internet over analog voice line, extremely slow (low bandwidth)

-Satelite : Can be used anywhere but requires clear line of sight

-Cable : High speed, always on uses a coaxial cable as a medium to bring data and TV

Back 8

Physical Layer Protocols & Services

The purpose of the Physical layer is to convert a frame into a series of electrical optical or microwave signals that represents the bits in each frame

Front 9

Throughput

Actual measured rate of data transfer

These factors include:

1. the amount of traffic

2. type of traffic

3. The number and type of network devices that the data is crossing

Back 9

Twisted pair

Unshielded twisted pair reduces outside interference & crosstalk because of the twisting of the wires

Front 10

CSMA/CA

1. Used in 802.11 wireless

2. more overhead

3. collisions exist

Back 10

Auto-MDIX

A network administrator is connecting two modern switches using a straight-through cable. The switches are new and have never been configured

1. The link between the two will work at the fastest speed supported by both sides

2.The link will work as full-duplex

3.The Auto-MDIX feature will configure the interfaces eliminating the need for a crossover cable

Front 11

Router Packet Forwarding Decision

The main purpose of routing process is to select the best path that are used to direct traffic to their final destination networks

Back 11

Introducing TCP

Transmission Control Protocol (TCP)

-Reliable delivery - detection of out of order and missing packets and the retransmitting of lost or corrupt data

Front 12

IPv4 Packet Header

The value in the Source & Destination field in an IPv4 header will stay the same during its transmission. The other options might change

Back 12

Network Address Translation (NAT)

Technology which provides a solution to IPv4 address depletion by allowing multiple devices to share on public IP address

Front 13

Router Memory

Memory | Volatile/Non-Volatile |Stores

1. RAM | Volatile | running config file, running IOS

2. ROM | Non-Volatile | Limited IOS

3. NVRAM | Non-Volatile | startup config file

4. Flash | Non-Volatile | IOS

Back 13

Router Bootup Process

1.Flash

2.TFTP CISCO IOS

3.ROM

4.NVRAM

5.TFTP Server Config File

6.Console

Front 14

Datagram Reassembly

UDP, no failure messages or retransmissions are required

Back 14

Public and Private IPv4 Addresses

Private address blocks are :

-Hosts that do not require access to the Internet can use private addresses

-10.0.0.0 - 10.255.255.255

-172.16.0.0 - 172.31.255.255

-192.168.0.0 - 192.168.255.255

Front 15

ICMPv4 and ICMPv6 Messages

The purpose of ICMP messages is to provide feedback about issues that are related to the proccessing of IP packets

Back 15

Basic Security of Wireless

-Change default values (password)

-Disable SSID broadcasting

-Configure Encryption using WPA (WPA2 Prefered, Enhanced Security)

Front 16

Remote Network Routing

If there are two or more possible routes to the same destination, metric is used to decide which route appears on the routing table. The lower the metric, the better the route

Back 16

Basic Security of Wireless

Wired Equivalency Protocol (WEP) : Every wireless device allowed to access the network must have the same WEP entered which makes it easily compromised

Wi-Fi Protected Access (WPA) : also uses encryption keys from 64 bits up to 256 bits. New keys are generated each time a connection is established with the AP

Front 17

IPv6 Router

-ipv6 unicast-routing (enables ipv6 routing)

-When the ipv6 unicast-routing command is implemented on a router, it enables the router as an IPv6 router

Back 17

Assigned IPv6 Multicast Addresses

Multicast address can only be destination addresses and not source addresses

Two common IPv6 assigned multicast groups include:

-FF02::1 All-nodes multicast group

all IPv6-enabled nodes (devices) on a local-link join

-FF02::2 All-routers multicast group

Front 18

Traceroute (tracert)

Routers drop traceroute packets if TTL field reaches 0

Back 18

The data link layer is the only OSI layer broken into two sublayers

LLC identifies the network layer encapsulated in the frame and allows multiple layer 3 protocols to use the same interface and media

Front 19

Frame Check Sequence

FCS : Support frame error detection which determines if errors occurred in transmission or reception

Back 19

MAC Sublayer

Provides three primary functions:

1. Frame delimiting

2. Addressing

3. Error Detection

Front 20

Layer 2 vs Layer 3 Switching

A layer 3 can use both MAC and IP addresses to make forwarding decisions!

An IP address can be assigned to a physical port of a Layer 3 switch. However, this is not supported in Layer 2

Back 20

DHCP Operation

1. The destination IP address is 255.255.255.255

2. The message comes from a client needing an IP address

3. All devices receive the message but, only a DHCP server replies

Front 21

Authentication, Authorization & Accounting

Authentication - Users and administrators must prove their identity

Authorization - network security authorization controls which resources the user can access and which operations the user is allowed to perform

Accounting - measures the resources a user consumes during access

Back 21

Block Unauthorized Access

login block-for 120 attempts 3 within 60

This command would help mitigate brute-force password attacks against the router.

Front 22

Backup and Restore using TFTP

Configuration files can be stored on a Trivial File Transfer Protocol (TFTP) server

copy startup-config tftp : save the configuration startup-config to a tftp server

Back 22

Situations for Media (Cables)

Copper Cables : Desktop PCs, Horizontal cabling structure

Fiber Optic : Long-haul networks, backbone cabling

Wireless : Guest access, waiting rooms

Front 23

Router bootup process

Stage 1 : Perform the POST

Stage 2 : Load the bootstrap program

Stage 3 : Locate and load the cisco IOS

Stage 4 : Locate and load the config file

Back 23

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