发信人: aaa234(我只只在乎你)
整理人: reynolds(2001-07-02 08:38:04), 站内信件
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6. Differentiate between the following WAN services: X.25 / LAPB, Frame Relay, I
SDN / LAPD, SDLC. HDLC, PPP and DDR.
X.25 - ITU-T standard that defines how connections between DTE and DCE are maint
ained for remote terminal access and computer communications in PDNs. X.25 speci
fies LAPB, a data link layer protocol, and PLP, a network layer protocol. Frame
Relay has to some degree superseded X.25.
Frame Relay - Industry-standard, switched data link layer protocol that handles
multiple virtual circuits using HDLC encapsulation between connected devices. Fr
ame Relay is more efficient than X.25, the protocol for which it is generally co
nsidered a replacement.
ISDN - Integrated Services Digital Network. Communication protocol, offered by t
elephone companies, that permits telephone networks to carry data, voice, and ot
her source traffic.
SDLC - Synchronous Data Link Control. SNA data link layer communications protoco
l. SDLC is a bit-oriented, full-duplex serial protocol that has spawned numerous
similar protocols, including HDLC and LAPB.
HDLC - High-Level Data Link Control. Bit-oriented synchronous data link layer pr
otocol developed by ISO. Derived from SDLC, HDLC specifies a data encapsulation
method on synchronous serial links using frame characters and checksums.
PPP - Point-to-Point Protocol. A successor to SLIP, PPP provides router-to-route
r and host-to-network connections over synchronous and asynchronous circuits.
DDR - dial-on-demand routing. Technique whereby a Cisco router can automatically
initiate and close a circuit-switched session as transmitting stations demand.
The router spoofs keep-alives so that end stations treat the session as active.
DDR permits routing over ISDN or telephone lines using an external ISDN terminal
adaptor or modem.
7. Log into a router in both user and privileged modes.
User EXEC – User mode entered by logging in. Prompt will be Router>. To exit
use the logout command.
Privileged EXEC – From user EXEC mode, use the enable EXEC command. Prompt will
be Router#. To exit to user EXEC mode use the disable command.
8. Use the context-sensitive help facility.
Entering a question mark (?) at the system prompt displays a list of commands av
ailable for each command mode. You can also get a list of any command’s associa
ted keyworkd and arguments with the context-sensitive help feature. To get help
specific to a command mode, a command, a keyword, or arguments perform one of th
e following:
Task Command
Obtain a brief description of the help system in and help
Command mode.
Configure a line or lines to receive help for the full set of full-help
User-level commands when a user types ?.
Configure a line to receive help for the full set of user-level terminal full-he
lp
Commands for this exec session.
Obtain a list of commands that begins with a particular abbreviated-command-entr
y?
Character string.
Complete a partial command name. abbreviated-command-entry<Tab>
List all commands available for a particular command mode. ?
List a command’s associated keywords. command ?
List a keyword’s associated arguments. Command keyword ?
9. Use the command history and editing features.
With the current IOS release, the user interface provides a history or record of
commands that you have entered. This feature is particularly useful for recalli
ng long or complex command entries including access lists. By default, the syste
m records 10 command lines in its history buffer. To set the number of command l
ines recorded during the current terminal session use the following command:
terminal history [size number-of-lines]
To configure the number of command lines the system records, complete the follow
ing command from line configuration mode:
history [size number-of-lines]
Useful editing commands:
Crtl-P or the up arrow key Recall commands in the history buffer starting with t
he most recent
command.
Crtl-N or the down arrow Return to more recent commands in the history buffer af
ter recalling
commands with Crtl-P or the up arrow key.
Crtl-B or left arrow key Move the cursor back one character
Crtl-F or right arrow key Move the cursor forward one character
Crtl-A Move the cursor to the beginning of the command line
Crtl-E Move the cursor to the end of the command line
Esc B Move the cursor back one word
Esc F Move the cursor forward one word
Crtl-R or Crtl-L Redisplay the current command line
10. Examine router elements (RAM, ROM, CDP, show).
ROM Read Only, Hard Wired, Boot Strap, IOS, ROM Monitor
RAM IOS & Running Configuration (Main Memory)
NVRAM Startup Config – Saved via battery (10 yr Life Span)
Flash IOS – PCMCIA Cards or SIMMs
Shared RAM Packet Buffering – Not all platforms
The Cisco Discovery Protocol (CDP) is a media- and protocol-independent protocol
that runs on all Cisco-manufactured equipment including routers, bridges, acces
s servers and switches. CDP runs on all media that supports Subnetwork Access Pr
otocol (SNAP) including local area network, Frame Relay and ATM media. CDP runs
over the data link layer only.
specify the frequency of transmission of CDP updates. cdp timer seconds
specify the amount of time a receiving device should cdp holdtime seconds
hold the information sent by your device before
discarding it.
to disable CDP no cdp run
to disable CDP on an interface no cdp enable
delete the CDP table of information about neighbors clear cdp table
display cdp neighbor information show cdp neighbors [type number] [detail]
The show cdp neighbors command displays: Device ID, interface type and number, h
old-time settings, capabilities, platform and port ID information about neighbor
s. Using the detail option displays the following additional neighbor details: n
etwork address, enabled protocols and software version.
11. Manage configuration files from the privileged exec mode.
You can copy a configuration file from a TFTP server to the running configuratio
n or to the startup configuration. When you copy a configuration file to the run
ning configuration, you copy to and run the file from RAM. When you copy a confi
guration file to the startup configuration, you copy it to the nonvolatile rando
m-access memory (NVRAM).
Step 1 Copy a file from a TFTP server to the router copy tftp running-config
or
Copy tftp startup-config
Step 2 When prompted enter the IP address or domain ip-address or name
name of the server
Step 3 If prompted, enter the filename of the configuration filename
file
Configuration files can also be copied from an rcp server to the local router as
well. You must first specify the remote username:
ip rcmd remote-username username
Use steps as above except replace tftp with rcp
to view the configuration in NVRRAM show startup-config
to view the current running configuration show running-config
to re-execute the configuration commands located in NVRAM configure memory
to erase the contents of NVRAM erase startup-config
转自www.chinamcse.com
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