icnd第六章 管理网相络环境-

第六章

管理网络环境Slide

1

of

1Purpose:Emphasize:Note:

CDP

is

sent

usingmulticast

frame

with

the

MAC

address0100.0ccc.cccc.CDP协议Cisco

Discovery

Protocol

是一个提供关于直接相连的交换机、路由器和其它Cisco设备的综合信息的专有工具

CDP能够发现直接相邻的设备而不管这些设备所运行的是什么协议栈上层地址Cisco专有的链路层协议介质必须能够支持

SNAPTCP/IPCDP能发现并显示关于直接相连的Cisco设备的信息LANs

ATM

Others帧中继Novell

AppleTalk

OthersIPXSlide

1

of

1Purpose:Emphasize:

CDP

is

media-

and

protocol-independent

and

runs

on

all

Cisco-manufactured

equipment

including

routers,

access

servers,

switchesand

some

managed

hubs.

WithCDP,

network

management

applications

can

retrieve

the

device

type

and

SNMP

agent

address

of

neighboringdevices.

This

capability

enables

applications

to

send

SNMP

queries

to

neighboring

devices.CDP

allows

network

management

applications

to

dynamically

discover

Cisco

devices

that

are

neighbors.

CDP

runs

on

all

media

that

supportSubnetwork

Access

Protocol,

including

LAN

and

Frame

Relay.

CDP

runs

over

the

data

link

layer

only,

not

the

network

layer.

Therefore,

twosystems

that

support

different

network-layer

protocols

can

learn

about

each

other.Cached

CDP

information

is

available

to

network

management

applications.

Cisco

devices

never

forward

a

CDP

packet.

When

new

informationis

received,

old

information

is

discarded.

The

holdtime

determines

how

longto

keep

existinginformation

froma

neighbor.

CDP运行在使用10.3或更新版Cisco

IOS的路由器以及Cisco交换机和集线器上能获取的信息包括:设备名对应各协议的地址端口名角色特征平台CDPshow

cdpCDPCDP用CDP发现直接相邻的设备Slide

1

of

1Purpose:Emphasize:Note:

Some

of

the

CDP

commands

are

not

available

on

the

Cat

1900

switch,

like

“cdp

run”,

“show

cdp

traffic”,

and

“show

cdp

entry”.使用CDP交换机B路由器A路由器B交换机A

S0S1RouterA#sh

cdp

?Information

for

specific

neighbor

entryCDP

interface

status

and

configurationCDP

neighbor

entriesCDP

statisticsentryinterfaceneighborstraffic<cr>RouterA(config)#no

cdp

runRouterA(config)#interface

serial0RouterA(config-if)#no

cdp

enableSlide

1

of

1Purpose:Emphasize:

This

graphic

shows

the

showcdp

neighbors

command

initiated

froma

router,

which

displaysa

summary

of

the

capabilities

andaccess

details

for

the

CDP

neighbors.

The

showcdp

neighbors

detail

command

shows

detailed

information

about

the

same

devices.Note:

If

the

neighbor

is

a

Cat

1900

switch,

the

switch

mac

address

is

also

displayed.

If

the

switch

is

a

2900xl,

its

mac

address

is

not

displayed.交换机A同时也显示其Mac地址使用show

cdp

neighbor

命令RouterA#sh

cdp

neighborsCapability

Codes:

R

-

Router,

T

-

Trans

Bridge,

B

-

Source

Route

BridgeS

-

Switch,

H

-

Host,

I

-

IGMP,

r

-

RepeaterCapability

Platform Port

IDDevice

IDRouterBLocal

IntrfceSer

0SwitchA0050BD855780

Eth

0Holdtme148167RT

S25221900Ser

12

S0S1交换机B路由器A路由器B交换机ASlide

1

of

1Purpose:Emphasize:

The

example

shows

what

information

can

be

obtained

about

RouterA’s

neighbor.

CDP

is

one

way

to

learn

about

other

Ciscodevices

on

the

network.使用show

cdp

entry

命令RouterA#sh

cdp

entry

*Device

ID:

RouterBEntryaddress(es):IP

address:

Platform:

cisco

2522, Capabilities:

RouterInterface:

Serial0,

Port

ID

(outgoing

port):

Serial1Holdtime

:

168

secVersion

:Cisco

Internetwork

Operating

System

SoftwareIOS

(tm)

2500

Software

(C2500-JS-L),

Version

12.0(3),

RELEASE

SOFTWARE

(fci)Copyright

(c)

1986-1999

by

cisco

Systems,

Inc.Compiled

Mon

08-Feb-99

18:18

by

phanguye

S0S1交换机B路由器A路由器B交换机ASlide

1

of

1Purpose:Emphasize:Note:

The

holdtime

indicates

how

longthe

neighbor

information

will

be

kept

in

the

local

CDP

table.其它CDP命令RouterA#sh

cdp

trafficCDP

counters

:Packets

output:

56,

Input:

38Hdr

syntax:

0,

Chksum

error:

0,

Encaps

failed:

3No

memory:

0,

Invalid

packet:

0,

Fragmented:

0RouterA#sh

cdp

interfaceBRI0

is

administratively

down,

line

protocol

is

downEncapsulation

HDLCSending

CDP

packets

every

60

secondsHoldtime

is

180

seconds

S0S1交换机B路由器A路由器B交换机ASlide

1

of

1Purpose:Emphasize:

Another

way

to

learn

about

aremote

device

is

to

connect

to

it.

Telnet,

avirtual

terminal

protocol

that

is

part

of

the

TCP/IP

protocolsuite,

allows

connections

to

remote

hosts.

By

default,

a

router

canhave

up

to

five

simultaneous

incomingTelnet

sessions.

With

Cisco’simplementation

of

TCP/IP,

you

need

not

enter

the

connect

or

telnet

command

to

establish

a

Telnet

connection.

If

you

prefer,

you

can

just

enter

the

learned

host

name,

the

router

will

resolve

the

hostname

usingDNS

ora

local

host

table.

To

enda

Telnet

session,

use

the

exit

orlogout

EXECcommand.These

are

alternate

commands

for

the

operations

listed

on

the

graphic:Initiatea

session:Denver>

connect

parisDenver>

parisDenver>

52Resume

a

session

(enter

sessionnumberor

name):Denver>

1Paris>End

a

session:Paris>

exitNote:

The

Cat

1900

can

accept

incoming

telnet

connections

but

can

not

initiate

an

outgoing

telnet

session.用Telnet连接到远端设备远端设备

S0S1RouterA#telnet

Trying

...

OpenCatalyst

1900

Management

ConsoleCopyright

(c)

Cisco

Systems,

Inc.

1993-1998All

rights

reserved.Enterprise

Edition

Software00-90-86-73-33-4073-2239-06FAA02359H8K

WS-C1924-EN

FAA0237X0FQEthernet

Address:PCA

Number:PCA

Serial

Number:Model

Number:System

Serial

Number:..SwitchB>交换机B路由器A路由器B交换机ASlide

1

of

1Purpose:Emphasize:Note:

This

output

was

taken

froma2522.

Line

11

=

VTY

0.You

can

send

messages

to

one

or

all

terminal

lines.

A

common

reason

for

doing

this

is

to

inform

usersof

an

impending

shutdown.

To

send

amessage

to

other

terminals,

issue

the

following

command:send

{line-number

|

*}Syntax

Descriptionline-number

Specifies

the

line

number

to

whichthe

message

will

be

sent.*

Indicates

that

the

message

will

be

sent

to

all

lines.The

systemprompts

for

the

message,

which

can

be

up

to

500

characters

long.

End

the

message

by

entering

Ctrl-Z.

Enter

Ctrl-C

to

abort

thecommand.查看Telnet连接

S0S1RouterA#sh

sessionConn

HostAddressByteIdle

Conn

Name1

01

* 2

00

RouterA#shLineuserUserHost(s)IdleLocation* 0

con03211

vty0idle1

交换机B路由器A路由器B交换机ASlide

1

of

1Purpose:Emphasize:Note:

Disconnect

without

the

session

number

disconnect

that

last

active

session.RouterA#disconnectClosing

connection

to

[confirm]RouterA#clear

line

11[confirm][OK]断开一个Telnet会话清除由远端设备建立的会话断开由自己建立的当前会话

S0S1交换机B路由器A路由器B交换机ASlide

1

of

1Purpose:Emphasize:

As

you

use

CDP

and

Telnet

you

should

note

the

information

retrieved

from

the

devices

you

successfullycontacted.

Documentingthat

information

helps

put

the

network

into

a

visual

perspective,

and

can

be

referenced

at

alater

time.This

concludes

the

network

discovery

portion

of

the

chapter.

In

the

next

section,

we

will

discuss

configurationfile

and

IOS

image

management.使用ping

和trace

命令

测试对远端设备的连接性和路径Router##ping

0Type

escape

sequence

to

abort.Sending

5,

100-byte

ICMP

Echos

to

0,

timeout

is

2

seconds:!!!!!Success

rate

is

100

percent

(5/5),

round-trip

min/avg/max

=

4/4/4

msRouter#trace

0Type

escape

sequence

to

abort.Tracing

the

route

to

01

0

4

msec

4

msec

4

msecRouter#Slide

1

of

1Purpose:Emphasize:

In

a

later

slide,

there

is

a

very

detailed

flowchartof

the

router

startup

process.路由器加电/启动顺序加电自检(POST)加载并运行启动引导微代码寻找IOS映象文件加载IOS映象文件寻找配置文件加载配置文件正常运行Slide

1

of

1Purpose:Emphasize:Note:RAM

-

Packet

buffers,

running

configurations,

running

IOSROM

-

POST,

Rom

Monitor,

Baby

IOS

(Rxboot)NVRAM

-

Backup

configurations,

ConfigregisterFlash

-

IOSFlash

memory

is

non-volatile.

It

behaves

likea

file

system.

Itis

more

expensive

than

NVRAM.

It

is

readable

and

writeable.

The

2500

routers

runfromflash.

If

it

is

running

IOS

fromflash,

then

the

flash

is

in

the

readable

state.

Use

the

boot

systemcommand

to

boot

an

IOS

froma

tftp

serverso

the

2500

can

run

from

RAM

if

you

need

to

writeor

erase

flash

online.路由器内部组件RAM配置寄存器ROMFlashNVRAM端口Slide

1

of

1Purpose:Emphasize:Note:

Mini

IOS

is

the

Rxboot

mode.One

use

of

the

Rom

Monitor

is

for

password

recovery.

From

Rom

Monitor,

you

can

set

the

config

register

to

0x2142

so

the

NVRAM

will

beignored

during

startup.ROM功能ROM引导Bootstarp:用于在初始化是启动路由器。通过读配置寄存器决定如何启动及启动后的动作，例如装载IOS软件。加电自检Post：用于检查路由器硬件的基本功能以及决定哪些部件可用。

Rom监视：用于完成测试和排错的底层操作系统。部分mimi：IOS子集，部分IOS用于将新的软件映像装进闪存并执行其他维护操作。BootstrapMini

IOSROMmonitorPOSTshow

version控制台Slide

1

of

1Purpose:Emphasize:

Use

the

show

version

command

to

display

the

valueof

the

Config

register

setting.

Whenyou

change

the

config

register,

we

will

seefrom

the

show

version

output:Configuration

register

is

0x2102

(will

be

0x2142

at

next

reload).The

new

config

register

value

will

be

used

atthe

next

reload.确认当前的配置寄存器值wg_ro_a#show

versionCisco

Internetwork

Operating

System

SoftwareIOS

(tm)

2500

Software

(C2500-JS-L),

Version

12.0(3),

RELEASE

SOFTWARE

(fc1)Copyright

(c)

1986-1999

by

cisco

Systems,

Inc.Compiled

Mon

08-Feb-99

18:18

by

phanguyeImage

text-base:

0x03050C84,

data-base:

0x00001000ROM:

System

Bootstrap,

Version

11.0(10c),

SOFTWAREBOOTFLASH:

3000

Bootstrap

Software

(IGS-BOOT-R),

Version

11.0(10c),

RELEASE

SOFTWARE

(fc1)wg_ro_a

uptime

is

20

minutesSystem

restarted

by

reloadSystem

image

file

is

"flash:c2500-js-l_120-3.bin"--More--Configuration

register

is

0x2102用命令show

version所显示的配置寄存器值Slide

1

of

4Purpose:

This

slide

shows

how

to

use

the

config-register

command

to

set

the

boot

field.

Emphasize:

Layer

1—Shows

the

example

of

theconfig-register

command.

Itassumes

the

network

administrator

will

set

the

register

to

the

default

setting

of

0x2102.

(0x

means

the

number

is

inhex).In

this

course,

limit

the

focusto

the

boot

field

that

is

formed

by

bits

3,

2,

1

and

0.设定配置寄存器的值Router#configure

terminalRouter(config)#config-register

0x2102[Ctrl-Z]Router#reload–配置寄存器的3,2,1和0位是启动选项位Slide

2

of

4Purpose:Emphasize:

Layer

2—Adds

the

table

that

identifies

the

boot

field

Configuration

Register

values

and

meanings.

The

first

value,

0x0,

enters

ROMmonitor

mode.

Your

students

should

not

enter

this

mode

except

for

password

recovery.

Refer

students

to

the

Doc

CD

Romor

the

“Installationand

Maintenance

of

Cisco

Routers

(IMCR)”

hardware

course

for

more

details.设定配置寄存器的值配置寄存器启动选项部分的值0x0含义进入ROM

monitor模式(人工启动时用b

命令)Router#configure

terminalRouter(config)#config-register

0x2102[Ctrl-Z]Router#reload–配置寄存器的3,2,1和0位是启动选项位Slide

3

of

4Purpose:Emphasize:

Layer

3—Adds

the

second

boot

field

value

0x1.

This

setting

automatically

boots

the

system

from

ROM

and

provides

a

subset

ofthe

Cisco

IOS

image

(Rxboot

mode).

Routing

is

not

enabled

in

the

Rxboot

mode.

However,

the

router

has

IP

functionalityin

the

Rxboot

mode.For

example,

from

the

Rxboot

mode,

the

router

can

performa

tftp

transfers

to

copy

an

IOS

image

froma

tftp

server

to

its

flash

memory.Some

routers

can

store

a

full

IOS

image

in

ROM.设定配置寄存器的值配置寄存器启动选项部分的值0x00x1含义进入ROM

monitor模式(人工启动时用b

命令)自动从ROM启动(提供完整IOS的一个子集)Router#configure

terminalRouter(config)#config-register

0x2102[Ctrl-Z]Router#reload–配置寄存器的3,2,1和0位是启动选项位Slide

4

of

4Purpose:Emphasize:

Layer

4—Finishes

with

the

third

case,

aboot

field

setting

in

the

range

of

0x2

to

0xF.

The

entry

of

a

ConfigurationRegister

value

inthe

0x2

to

0xF

range

is

significant.

When

the

router

attempts

to

boot

from

the

net

(Netboot),

the

bootstrap

programgenerates

an

IOS

filenamebased

on

the

value

of

the

boot

field.

For

example,

with

the

setting

0x2,

the

default

IOS

filename

generated

will

be

cisco2-xxxx,

where

xxxx

referstoa

processor

name

(for

example,

2500).

Again,

refer

students

to

the

IMCR

course

for

details.You

use

the

config-register

command

to

change

the

value.Notice

that

the

bottomlines

of

the

showversion

output

indicates

what

the

value

the

config

register

will

be

on

the

next

reload.–用命令show

version来检查配置寄存器的值设定配置寄存器的值配置寄存器启动选项部分的值0x00x2

to

0xF0x1含义进入ROM

monitor模式(人工启动时用b

命令)自动从ROM启动(提供完整IOS的一个子集)检查NVRAM之boot

system命令(如果路由器配有Flash则缺省值为0x2)Router#configure

terminalRouter(config)#config-register

0x2102[Ctrl-Z]Router#reload–配置寄存器的3,2,1和0位是启动选项位Slide

1

of

1Purpose:Emphasize:Note:

The

2500

series

routers

do

not

operate

this

way.

The

2500

series

routers

normally

run

IOS

fromflash.

The

IOS

in

flash

is

not

compressedbut

it

is

relocatable.

Relocatable

means

the

IOS

image

can

be

ran

fromflash

or

from

RAM.The

2500

can

run

from

RAMif

you

use

the

“boot

system

tftp”

command

to

boot

the

IOSimage.The

Rxboot

mode

is

also

ran

from

RAM

on

the

2500

routers.从Flash加载IOS映象文件FlashIOSshow

flashFlash中的映象文件解压缩到RAM中控制台RAMIOSSlide

1

of

1Purpose:Emphasize:Note:The

current

state

of

the

flash

memory

is

in

Read

ONLY

mode.

It

is

running

IOS

fromflash.This

router

has

atotal

of

16MBof

flash

memory.

The

flash

contains

one

IOS

image

and

there

are

6.69MB

available

space

left

in

flash.使用show

flash

命令wg_ro_a#sh

flashSystem

flash

directory:File

Length

Name/status1

10084696

c2500-js-l_120-3.bin[10084760

bytes

used,

6692456

available,

16777216

total]16384K

bytes

of

processor

board

System

flash

(Read

ONLY)Slide

1

of

1Purpose:Emphasize:

Using

the

default

configregister

value

(0x2102),

the

router

will

load

the

configfrom

NVRAM

at

startup.加载配置文件IOSshowstartup-configshowrunning-config控制台Setup

utility从NVRAM中加载并运行配置文件如果NVRAM中没有配置文件,进入setup模式ConfigConfigRAMNVRAMSlide

1

of

1Purpose:

This

slide

is

a

repeated

slide

fromchapter

4.Emphasize:使用show

running

和showstartup

命令wg_ro_c#show

startup-configUsing

1359

out

of

32762

bytes!version

12.0!--

More

--wg_ro_c#show

running-configBuilding

configuration...Current

configuration:!version

12.0!--

More

--存在RAM中 存在NVRAM中显示当前运行的和保存的配置情况Slide

1

of

4Purpose:Emphasize:

Whencopying

to

RAM,

it

is

always

a

merge

notan

overwrite.Explain

on

the

board

the

difference

between

a

merge

versus

an

overwrite.Explain

the

general

syntaxof

the

copy

command:

copy

<from>

<to>With

12.0,

the

copy

command

supports

anewsyntax.

The

newsyntax

is

explained

in

a

later

slide.配置参数的来源ConfigConfigRAMNVRAM–

NVRAMcopy

running

startupcopy

startup

running(合并)Slide

2

of

4Purpose:Emphasize:配置参数的来源ConfigConfigRAMNVRAMNVRAMTerminalcopy

running

startupcopy

startup

running(合并)config

term(合并)Slide

3

of

4Purpose:Emphasize:Note:The

Cisco

TFTP

server

software

which

runs

on

Windows

95/98/NT

can

be

downloaded

from

the

url

listed

below:/cgi-bin/tablebuild.pl/tftpA

Cisco

router

can

also

be

configured

to

be

a

tftp

server

using

the

“tftp-server”

global

configuration

command.ConfigConfigConsoleRAMNVRAM–

NVRAMTerminalTFTP服务器copy

running

startupTFTP服务器copy

start

tftpcopy

tftp

startcopy

run

tftpcopy

tftp

runcopy

startup

runningconfig

term配置参数的来源Slide

4

of

4Purpose:Emphasize:配置参数的来源ConfigConfigConsoleRAMNVRAM–

NVRAMTerminalTFTP

server删除启动配置文件copy

running

startupTFTP服务器Blank000000000000erasestartcopy

startup

runningconfig

termcopy

tftp

runcopy

tftp

startcopy

start

tftpcopy

run

tftpSlide

1

of

1Purpose:Emphasize:

Note:

Release

12.0

supports

new

syntax

for

the

“copy”

command.使用copy

run

tftp

和copy

tftprun

命令wg_ro_a#copy

running-config

tftpAddress

or

name

of

remote

host

[]?

Destination

filename

[running-config]?

wgroa.cfg.!!1684

bytes

copied

in

13.300

secs

(129

bytes/sec)wg_ro_a#copy

tftp

running-configAddress

or

name

of

remote

host

[]?

Source

filename

[]?

wgroa.cfgDestination

filename

[running-config]?Accessing

t/wgroa.cfg...Loading

wgroa.cfg

from

(via

Ethernet0):

![OK

-

1684/3072

bytes]1684

bytes

copied

in

17.692

secs

(99

bytes/sec)Slide

1

of

1Purpose:Emphasize:

In

release

12.0,

there

are

new

copy

commands.

These

new

commands

treat

the

RAM,

Flash,

NVRAM,

tftp,

ftp,

etc…as

afilesystem.

Since

atthe

time

whenthis

class

was

developed,

the

most

common

IOS

in

the

field

is

pre

12.0,

these

12.0

commands

are

not

covered

indetail

in

this

class.Cisco文件系统与设备RAMNVRAMTFTP服务器Flashflash:system:nvram:tftp:Slide

1

of

1Purpose:Emphasize:

This

section

introduces

topics

on

managingyour

configuration

file

and

IOS

image.管理IOS映象文件网络服务器FLASH路由器c2500-js-l_120-3.bin网络服务器Slide

1

of

4Purpose:

This

slide

establishes

an

overviewand

reason

to

use

the

TFTP

server

asaload

source

or

backup

destination

for

Cisco

IOS

software.It

then

presents

the

preparation

details

needed

before

executing

TFTP

copies.Emphasize:

Geographicallydistributed

routers

need

a

source

or

backup

location

for

software

images.

Using

a

network

server

allows

image

andconfiguration

uploads

and

downloads

over

the

network.

The

network

server

can

be

another

router,

a

workstation,

or

a

host

system.A

router

can

be

configured

as

a

tftp

server

using

the

tftp-server

global

configurationcommand.Layer

one

-

First,

you

need

to

check

that

you

have

access

to

the

network

server.

Example,

use

the

ping

command

to

see

if

you

can

reach

theserver.映象文件备份的准备确认可以访问到网络服务路由器网络服务器Slide

2

of

4Purpose:Emphasize:

Layer2

—

you

need

to

check

that

you

have

enoughdisk

space

on

the

tftp

server

to

house

the

new

system

image.

On

the

router,

usethe

showflash

command

to

determine

the

length

of

the

IOS

image.映象文件备份的准备确认可以访问到网络服务确认服务器上有足够的空间路由器网络服务器Slide

2

of

4Purpose:Emphasize:

Layer

3

—

you

need

to

check

the

naming

conventions

required

on

the

server.

Example,

what

is

the

maxnumberof

charactersallowed

in

the

filename

by

the

server’s

O.S?

What

is

the

max

number

of

characters

allowed

in

the

filename

extension

by

the

server’s

O.S?映象文件备份的准备确认可以访问到网络服务确认服务器上有足够的空间确认文件名路由器c2500-js-l_120-3.bin网络服务器Slide

4

of

4Purpose:Emphasize:

Layer

4—Onsome

Unix

server,

you

mayhave

to

first

create

the

file

first

before

you

can

download

the

IOS

image

from

the

router

tothe

tftp

server.

You

can

use

the

“touch”

Unix

command

to

create

an

empty

file

on

the

Unix

server.映象文件备份的准备路由器c2500-js-l_120-3.bin网络服务器确认可以访问到网络服务确认服务器上有足够的空间确认文件名需要时在服务器上创建文件Slide

1

of

1Purpose:Emphasize:

The

show

flash

command

is

an

important

tool

to

use

to

gather

information

about

your

router

memory

and

image

file.

Cautionstudents

that

they

must

know

that

they

are

loading

the

correct

and

appropriate

image.

The

name

for

the

Cisco

IOS

image

file

contains

multipleparts,

each

withaspecific

meaning:The

first

part

of

the

image

name

contains

the

platform

onwhichthe

image

runs.

In

this

example,

the

platform

is

C2500.The

second

partof

the

name

identifies

the

special

capabilities

of

the

image

file.

A

letter

or

series

of

letters

identifies

the

feature

sets

supported

inthat

image.

In

this

example,

the

j

indicates

this

is

an

enterprise

image,

and

the

s

indicates

it

contains

extended

capabilities.The

third

part

of

the

name

specifies

where

the

image

runs

and

if

the

file

is

compressed.

In

this

example,

l

indicates

the

file

is

relocatable

and

notcompressed.

Relocatable

means

the

IOS

can

be

ran

fromflash

or

from

RAM.

Youshould

be

careful

in

reading

the

Cisco

IOS

image

filename.Some

fonts

display

the

lowercase

letter

“l”

and

the

number1

as

the

same

character.

Howyou

type

the

characters

will

impact

the

ability

of

therouter

to

load

the

files

correctly.The

fourth

part

of

the

name

indicates

the

version

number.

In

this

example,

the

versionnumber

is

12.0

(3).The

final

partof

the

name

is

the

file

extension.

The

.bin

extension

indicates

this

file

isabinary

executable

file.The

Cisco

IOS

software

naming

conventions,

name

part

field

meaning,

image

content,

and

other

details

are

subject

to

change.

Refer

to

CiscoConnection

Online

(CCO)

for

updated

details.wg_ro_a#show

flashSystem

flash

directory:File

Length

Name/status1

10084696

c2500-js-l_120-3.bin[10084760

bytes

used,

6692456

available,

16777216

total]16384K

bytes

of

processor

board

System

flash

(Read

ONLY)确认存贮空间并解析文件名确认Flash中有足够空间来存放IOS映象文件Slide

1

of

1Purpose:

This

slide

discusses

how

to

create

a

backup

version

of

a

Cisco

IOS

software

image

toatftp

server.Emphasize:

Routers

by

default

comes

withFlash

memory

that

have

a

preloaded

copy

of

the

Cisco

IOS

software.

Although

Flash

is

extremelyreliable—good

for

65

years

and

100,000

rewrites—it

is

a

good

idea

to

make

a

backup

copy

of

the

Cisco

IOS

software

if

you

have

atftp

serveravailable.

If

you

had

to

replace

Flash

memory

for

some

reason,

you

would

haveabackup

copy

at

the

revision

level

currently

running

on

yournetwork.The

copy

command

screen

output

varies

depending

on

the

Cisco

IOS

software

level.Determine

the

platform

type

of

your

tftp

server

prior

to

beginning

the

backup

procedure.

The

tftp

server

may

be

runningWindows,

UNIX,

Macor

other

O.S

.

Filename

and

directory

access

procedures

may