CCNA

Cisco IOS File System and Devices
Managing Cisco IOS Images
wg_ro_a#show flash

System flash directory:
File Length Name/status
1 10084696 c2500-js-l_120-3.bin

[10084760 bytes used, 6692456 available, 16777216 total]
16384K bytes of processor board System flash (Read ONLY)
Verifying Memory Image Filenames
Creating a Software Image Backup
Upgrading the Image from the Network
LAB
Install TFTP server on a virtual machine
Connect the machine to a Router
To see the content of Flash file
#show Flash
To copy flash
#Copy flash tftp
supply IP address of TFTP Server and file name
To copy running-configuration
#copy running-config tftp
supply IP address of TFTP Server and file name


Resolving Host Names
To use a hostname rather than an IP address to connect to a remote device
Two ways to resolve hostnames to IP addresses
building a host table on each router
building a Domain Name System (DNS) server





Resolving Host Names
Building a host table
ip host host_name ip_address
R1(config)#ip host com1 10.0.0.1
R1(config)#ip host com2 10.0.0.2

To view table
R1#show hosts

To verify that the host table resolves names, try ping hostnames at a router prompt.

Password Recovery
Normal Boot Sequence
POST
Bootstrap
IOS
Startup
Running
This setup is decided by configuration register value
Configuration Register
Default
2102
Bit
Decimal
This means that bits 13, 8, and 1 are on.
To ignore NVRAM the 6th bit should be made ON
When the 6th bit is turned on the value will be 2142


Password Recovery
Show version will give configuration register value
Password is stored in NVRAM
To by pass NVRAM during boot sequence we need to change the configuration register value
To change the CR values press Ctr+Break and go to ROM monitor mode
Password Recovery
Router 2500
o/r 0x2142
i
Router 2600
confreg 0x2142
>reset

WAN vs LAN
Distance between WAN and LAN
WAN speed is less
WAN is leased from Service provider

Remote Access Overview
A WAN is a data communications network covering a relatively broad geographical area.

A network administrator designing a remote network must weight issues concerning users needs such as bandwidth and cost of the variable available technologies.
WAN Overview
Service
Provider
WANs connect sites
Connection requirements vary depending on user requirements and cost
WAN technology/terminology
Devices on the subscriber premises are called customer premises equipment (CPE).
The subscriber owns the CPE or leases the CPE from the service provider.
A copper or fiber cable connects the CPE to the service provider’s nearest exchange or central office (CO). A central office (CO) is sometimes referred to as a point of presence (POP)
This cabling is often called the local loop, or "last-mile".



CPE (Customer Premises Equipment) are equipments located at the customer’s site, they are owned, operated and managed by the customer.

WAN technology/terminology


A demarcation point is where customer premises equipment (CPE) ends, and local loop begins.
The local loop is the cabling from demarcation point to Central Office (CO).
WAN technology/terminology
Devices that put data on the local loop are called data communications equipment (DCE).
The customer devices that pass the data to the DCE are called data terminal equipment (DTE).
The DCE primarily provides an interface for the DTE into the communication link on the WAN cloud.

The DTE/DCE interface uses various physical layer protocols, such as V.35.
These protocols establish the codes and electrical parameters the devices use to communicate with each other.
WAN Devices
Modems transmit data over voice-grade telephone lines by modulating and demodulating the signal.
The digital signals are superimposed on an analog voice signal that is modulated for transmission.
The modulated signal can be heard as a series of whistles by turning on the internal modem speaker.
At the receiving end the analog signals are returned to their digital form, or demodulated
WANs - Data Link Encapsulation
The data link layer protocols define how data is encapsulated for transmission to remote sites, and the mechanisms for transferring the resulting frames.
A variety of different technologies are used, such as ISDN, Frame Relay or Asynchronous Transfer Mode (ATM).
These protocols use the same basic framing mechanism, high-level data link control (HDLC)

WAN Technologies Overview
Covers a relative broad area
Use transmission facilities leased from service provider
Carries different traffic (voice, video and data)
Dedicated
T1, E1, T3, E3
DSL
SONET
Analog
Dial-up modems
Cable modems
Wireless
Switched
Circuit Switched
POTS
ISDN
Packet Switched
X.25
Frame Relay
ATM
Dedicated Digital Services
Dedicated Digital Services provide full-time connectivity through a point-to-point link
T series in U.S. and E series in Europe
Uses time division multiplexing and assign time slots for transmissions
T1 = 1.544 Mbps E1 = 2.048 Mbps
T3 = 44.736 Mbps E3 = 34.368 Mbps



Digital Subscriber Lines
Digital Subscriber Line (DSL) technology is a broadband technology that uses existing twisted-pair telephone lines to transport high-bandwidth data to service subscribers.
The two basic types of DSL technologies are asymmetric (ADSL) and symmetric (SDSL).
All forms of DSL service are categorized as ADSL or SDSL and there are several varieties of each type.
Asymmetric service provides higher download or downstream bandwidth to the user than upload bandwidth.
Symmetric service provides the same capacity in both directions.

Analog Services
Dial-up Modems (switched analog)
Standard that can provides 56 kbps download speed and 33.6 kbps upload speed.
With the download path, there is a digital-to-analogue conversion at the client side.
With the upload path, there is a analogue-to-digital conversion at the client side.

Cable Modems (Shared Analog)
Cable TV provides residential premises with a coaxial cable that has a bandwidth of 750MHz
The bandwidth is divided into 6 MHz band using FDM for each TV channel
A "Cable Modem" is a device that allows high-speed data access (Internet) via cable TV network.
A cable modem will typically have two connections because a splitter delivers the TV bands to TV set and the internet access bands to PC via a cable box
The splitter delivers the TV bands to TV set and the internet access bands to PC via a cable box


Wireless
Terrestrial
Bandwidths typically in the 11 Mbps range
Cost is relatively low
Line-of-sight is usually required
Usage is moderate

Satellite
Can serve mobile users and remote users
Usage is widespread
Cost is very high
Circuit Switched Services
Integrated Services Digital Network (ISDN)
Historically important--first dial-up digital service
Max. bandwidth = 128 kbps for BRI (Basic Rate Interface)
2 B channels @ 64kps and 1 D channel @ 16kps
B channels are voice/data channels; D for signaling

Integrated Services Digital Network

Asynchronous Transfer Mode (ATM)
Communications providers saw a need for a permanent shared network technology that offered very low latency and jitter at much higher bandwidths.
ATM has data rates beyond 155 Mbps.
ATM is a technology that is capable of transferring voice, video, and data through private and public networks.
It is built on a cell-based architecture rather than on a frame-based architecture.
ATM cells are always a fixed length of 53 bytes.
The 53 byte ATM cell contains a 5 byte ATM header followed by 48 bytes of ATM payload.
Small, fixed-length cells are well suited for carrying voice and video traffic because this traffic is intolerant of delay.
Video and voice traffic do not have to wait for a larger data packet to be transmitted.
The 53 byte ATM cell is less efficient than the bigger frames and packets of Frame Relay
A typical ATM line needs almost 20% greater bandwidth than Frame Relay
WAN Connection Types
Leased lines
It is a pre-established WAN communications path from the CPE, through the DCE switch, to the CPE of the remote site, allowing DTE networks to communicate at any time with no setup procedures before transmitting data.
Circuit switching
Sets up line like a phone call. No data can transfer before the end-to-end connection is established.
WAN Connection Types
Packet switching
WAN switching method that allows you to share bandwidth with other companies to save money. As long as you are not constantly transmitting data and are instead using bursty data transfers, packet switching can save you a lot of money.
However, if you have constant data transfers, then you will need to get a leased line.
Frame Relay and X.25 are packet switching technologies.
Defining WAN Encapsulation Protocols
Each WAN connection uses an encapsulation protocol to encapsulate traffic while it crossing the WAN link.

The choice of the encapsulation protocol depends on the underlying WAN technology and the communicating equipment.
Defining WAN Encapsulation Protocols
Typical WAN encapsulation types include the following:

Point-to-Point Protocol (PPP)
Serial Line Internet Protocol (SLIP)
High-Level Data Link Control Protocol (HDLC)
X.25 / Link Access Procedure Balanced (LAPB)
Frame Relay
Asynchronous Transfer Mode (ATM)
Determining the WAN Type to Use
Availability
Each type of service may be available in certain geographical areas.
Bandwidth
Determining usage over the WAN is important to evaluate the most cost-effective WAN service.
Cost
Making a compromise between the traffic you need to transfer and the type of service with the available cost that will suit you.
Max. WAN Speeds for WAN Connections
Leased Line
Circuit-switched
PPP, SLIP, HDLC
HDLC, PPP, SLIP
Packet-switched
X.25, Frame Relay, ATM
Typical WAN Encapsulation Protocols: Layer 2
Telephone
Company
Service
Provider
WAN Protocols
Point to Point - HDLC, PPP
Multipoint - Frame Relay, X.25 and ATM
E0
S0
S0
WAN
LAN
Network
Datalink
Physical
HDLC – Proprietary – cisco device default

PPP - Open
Flag
Address
Control
Data
FCS
Flag
HDLC
Supports only single protocol environments
Flag
Address
Control
Proprietary
Data
FCS
Flag
Cisco HDLC
HDLC Frame Format
Cisco’s HDLC has a proprietary data field to support
multiprotocol environments
HDLC Command
Router(config-if)#encapsulation hdlc
Enable hdlc encapsulation
HDLC is the default encapsulation on
synchronous serial interfaces
PPP Encapsulation
PPP is open standard
HDLC is only for encapsulation
PPP provides encapsulation and authentication
PPP is made up of LCP and NCP
LCP is for link control and NCP for multiple protocol support and call back
Link setup and control
using LCP in PPP
An Overview of PPP
Feature
How It Operates
Protocol
Authentication
PAP
CHAP
Perform Challenge Handshake
Require a password

Compression
Compress data at source;
reproduce data at
destination
Error
Detection
Avoid frame looping
Monitor data dropped on link
Multilink
Load balancing across
multiple links
Multilink
Protocol (MP)
PPP LCP Configuration Options
PPP Authentication Overview
Two PPP authentication protocols:
PAP and CHAP


PPP Session Establishment
1 Link Establishment Phase
2 Optional Authentication Phase
3 Network-Layer Protocol Phase
Dialup or
Circuit-Switched
Network
Passwords sent in clear text
Selecting a PPP Authentication Protocol
Remote Router
(SantaCruz)
Central-Site Router
(HQ)
Hostname: santacruz
Password: boardwalk
username santacruz
password boardwalk
PAP
2-Way Handshake
“santacruz, boardwalk”
Accept/Reject
Selecting a PPP Authentication Protocol (cont.)
Remote Router
(SantaCruz)
Central-Site Router
(HQ)
Hostname: santacruz
Password: boardwalk
username santacruz
password boardwalk
CHAP
3-Way Handshake
Challenge
Response
Accept/Reject
Use “secret” known only to authenticator and peer
Configuring PPP and Authentication Overview
Service
Provider
Verify who
you are.
Router to Be Authenticated
(The router that initiated the call.)


ppp encapsulation

hostname
username / password
ppp authentication
Authenticating Router
(The router that received the call.)


ppp encapsulation

hostname
username / password
ppp authentication
Enabling PPP
Enabling PPP Authentication
Enabling PPP
Enabling PPP Authentication
Configuring PPP
Router(config-if)#encapsulation ppp
Enable PPP encapsulation
Configuring PPP Authentication
Router(config)#hostname name
Assigns a host name to your router
Router(config)#username name password password
Identifies the username and password of authenticating router
Configuring PPP Authentication
(cont.)
Router(config-if)#ppp authentication
{chap | chap pap | pap chap | pap}
Enables PAP and/or CHAP authentication
Configuring CHAP Example
hostname R1
username R2 password cisco
!
int serial 0
ip address 10.0.1.1 255.255.255.0
encapsulation ppp
ppp authentication CHAP

hostname R2
username R1 password cisco
!
int serial 0
ip address 10.0.1.2 255.255.255.0
encapsulation ppp
ppp authentication CHAP

R1
R2
PSTN/ISDN
Verifying HDLC and PPP Encapsulation Configuration
Router#show interface s0
Serial0 is up, line protocol is up
Hardware is HD64570
Internet address is 10.140.1.2/24
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation PPP, loopback not set, keepalive set (10 sec)
LCP Open
Open: IPCP, CDPCP
Last input 00:00:05, output 00:00:05, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
38021 packets input, 5656110 bytes, 0 no buffer
Received 23488 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
38097 packets output, 2135697 bytes, 0 underruns
0 output errors, 0 collisions, 6045 interface resets
0 output buffer failures, 0 output buffers swapped out
482 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up



Verifying PPP Authentication with the debug ppp authentication Command





4d20h: %LINK-3-UPDOWN: Interface Serial0, changed state to up
4d20h: Se0 PPP: Treating connection as a dedicated line
4d20h: Se0 PPP: Phase is AUTHENTICATING, by both
4d20h: Se0 CHAP: O CHALLENGE id 2 len 28 from ”left"
4d20h: Se0 CHAP: I CHALLENGE id 3 len 28 from ”right"
4d20h: Se0 CHAP: O RESPONSE id 3 len 28 from ”left"
4d20h: Se0 CHAP: I RESPONSE id 2 len 28 from ”right"
4d20h: Se0 CHAP: O SUCCESS id 2 len 4
4d20h: Se0 CHAP: I SUCCESS id 3 len 4
4d20h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0, changed state to up



debug ppp authentication successful CHAP output
R1
R2
Service
Provider
debug ppp authentication
What is ISDN?
Provider
network
Digital PBX
Small office
Home office
Voice, data, video
Telecommuter
Central site
Why ISDN?
ISDN - Integrated Services Digital Network
Telephone services -> Telecommunication services
Used for voice, data and video
BRI and PRI are used globally for ISDN
Channel
Mostly Used for
B
Circuit-switched data (HDLC, PPP)
Capacity
64 kbps
D
2B
ISDN Access Options
Signaling information
D
16/64 kbps
23 or 30B
BRI
PRI
D
Advantages of ISDN (2)
Bandwidth on Demand
adding new channels to the bundle of channels
Multiple devices
phone, fax, PC, videoconferencing system, router
Interfaces and Devices
TE1
TE2
TA
NT1
2W
4W
ISDN Ready
BRI Port
Analog devices:
phone, Serial port
After connecting to TA it becomes TE1
S/T interface
U interface
ISDN Switch
Interfaces and Devices
Function Group – A set of functions implemented by a device or software
Reference Point – The interface between two function group
Reference Points
LAB-ISDN
E0
Router(config)#hostname R1
R1(config)#username R2 password cisco
R1(config-if)#int bri 0
R1(config-if)# ip address 10.0.0.1 255.0.0.0
R1(config-if)#enacapsulation ppp
R1(config-if)#PPP authentication CHAP
R1(config-if)#no shut
Static Routes or default route
R1(config)#ip route 0.0.0.0 0.0.0.0 10.0.0.2
R1(config)#isdn switch-type basic-net3
Access List
R1(config)#dialer-list 1 protocol ip permit
R1(config)#int bri 0
R1(config-if)# dialer–group 1
R1(config-if)#dialer map ip 10.0.0.2 name R2 20
R1(config-if)#no shut
R1(config-if)#dialer idle-timeout 100
ISDN DDR configuration Commands
Packet Switched Services
X.25 (Connection-oriented)
Reliable--X.25 has been extensively debugged and is now very stable--literally no errors in modern X.25 networks
Store & Forward--Since X.25 stores the whole frame to error check it before forwarding it on to the destination, it has an inherent delay (unlike Frame Relay) and requires large, expensive memory buffering capabilities.

Frame Relay (Connectionless)
More efficient and much faster than X.25
Used mostly to forward LAN IP packets
Frame Relay Basics
FR is WAN layer2 protocol
FR developed in 1984, its a faster packet switching technology
In 1990 FR consortium was developed and extension added



Terminology
Frame Relay Network
R2
R1
End Device
Interface Device
Encapsulate Data
FR Network
DCE – Dedicated FR Switches, can be one or multiple
Access Line
Trunk Line
Virtual Circuit – an end to end connection between interface device - PVC or SVC
Data Link connection Identifiers (DLCI) number is the identification for VC, 16-1007
Committed Information Rate or CIR - agreed-upon bandwidth
Frame Relay there are two encapsulation types: Cisco and IETF
Local Management Interface (LMI) is a signaling standard used between your router and the first Frame Relay switch i - Cisco, ANSI, and Q.933A.
Frame Relay
Frame Relay differs from X.25 in several aspects.
Much simpler protocol that works at the data link layer, not the network layer.
Frame Relay implements no error or flow control.
The simplified handling of frames leads to reduced latency, and measures taken to avoid frame build-up at intermediate switches help reduce jitter.
Most Frame Relay connections are PVCs rather than SVCs.
Frame Relay provides permanent shared medium bandwidth connectivity that carries both voice and data traffic.

LAB - Frame Relay
192.168.1.2/24
192.168.2.2/24
R2
FR Switch
S0
192.168.2.1/24
R1
E0
S0
192.168.1.1/24
192.168.3.9/29
E0
100
200
192.168.3.10/29
DCE
DCE
Frame Relay Switch
Router#config t
Router(config)#hostname FRSwitch
FRSwitch(config)# frame-relay switching
FRSwitch(config)# int s 1/0
FRSwitch(config-if)#enacapsulation frame-relay
FRSwitch(config-if)# frame-relay intf-type DCE
FRSwitch(config-if)# clock rate 64000
FRSwitch(config-if)# frame-relay route 100 int serial 1/1 200
FRSwitch(config-if)#no shut
R1
Router#config t
Router(config)#hostname R1
R1(config)# int s 0
R1(config-if)#ip address 192.168.3.9 255.255.255.248
R1(config-if)#enacapsulation frame-relay
R1(config-if)# frame-relay intf-type DTE
R1(config-if)# frame-relay interface-dlci 100
R1(config-if-dlci)# exit
R1(config-if)#framerelay map ip 192.168.3.10 100
R1(config-if)#no shut