Course
notes: CISCO Exam 640-407
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Contents Page 2:
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Network congestion & Segmentation |
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Cisco router basic hardware overview |
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Router Components |
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Router Modes |
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Help & Editing commands |
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SHOW Commands |
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Passwords |
Course notes taken by Craig Ellis (MCP + CCNA)
Network congestion & Segmentation
Networks experience congestion
due to:
Broadcast / Multicast traffic on a
network
Routing Updates
Service Advertisements by hosts i.e.
Netware printer / file servers
DHCP / BOOTP (Boot Parameter
Service) traffic, i.e. Diskless client terminals
Name resolution, i.e. Microsoft NT
NetBIOS broadcasts
LAN Segmentation benefits are:
Reduces congestion due to broadcast
/ Multicast traffic and collisions, also increasing bandwidth to the user.
No traffic segmentation - may
cause problems:
A network could be using 1 collision
domain, 1 broadcast domain, 1 segment with no repeaters.
or 1 collision domain, 1 broadcast
domain, Multiple segments with repeaters using a star network set-up.
Traffic segmentation:
Resolved by using Bridges, i.e. 1
logical network, 1 broadcast domain, 2 collision domains (1 each side of the
bridge).
Bridges are store and forward
devices
Routers do not send broadcast
traffic unless specified.
Connections between routers &
bridges should use trunking, running full duplex mode dedicated link (no
collisions).
Cisco router basic hardware overview
Looking at the back of a Cisco
series 2500 router you would see (right to left):
Power lead connection, also off/on
switch with a green light to show power.
AUX port - Used for modem dial-in or
DDR link - This RJ45 port supports hardware flow control and operates at speeds
up to 38.4 kbps
Console port - Used for laptop
connection via a HyperTerminal administrative access to the router. This port
does not support hardware flow control.
BRI - Used to connect to ISDN - NTU.
Serial 0/1 ports - Used to connect
to CSU / DSU or other DCE device on the WAN.
AUI - Connect to Ethernet transceiver
box for connection to the LAN.
Token Ring - Connect to 802.5 MAU on
the LAN.
The 4 main router components are:
RAM (Random Access Memory), ROM (Read Only Memory), Cisco IOS (Internet work Operating System), NVRAM (Non Volatile RAM).
ROM:
Loads the bootstrap, then performs POST (Power On Self Test)
looks for the Cisco IOS image, looking in flash memory, TFTP and ROM.
Holds a small footprint of IOS to load if above are unavailable.
CISCO IOS:
Flash - EEPROM / Cisco IOS
For the up to date release check on the Cisco WWW page.
TFTP - Retrieve and load IOS from a TFTP server if required
ROM - Basic IOS image held in memory.
RAM:
Onboard upgradeable RAM used for:
Packet buffers, Route tables, Configuration information & host tables.
NVRAM:
Start-up configuration
Access TFTP server for network config.
Locates and loads configuration file or enters auto set-up mode.
Powering on your router 1st time:
When you first switch on a new Cisco router no information will be available and the router will display,
NVRAM INVALID DUE TO WRITE ERASE
Then you will be prompted to type in the initial configuration via a menu driven program.
You can look through the current interface settings during this time i.e. check Ethernet eo and serial s0,s1 port setups.
Enter a host name for your router i.e. type HOST1
Set-up a secret and enable passwords etc.
Press CTRL and C to quit at anytime but your information will not be saved.
Remember that you're RUNNING CONFIG. is what your currently programming on the router.
START-UP CONFIG is what's held in NVRAM.
The 3 ways to control the IOS boot up process:
FLASH MEMORY:
Type from privileged mode: ROUTER# boot system flash
ROUTER#
TFTP Server:
ROUTER# boot system tftp
ROUTER#
ROM:
ROUTER# boot system rom
USER Mode:
Used for basic set-up log in/out
ping etc…
Displays prompt ROUTER>
Privileged Mode:
Used for advanced set-up
configuration.
Displays prompt ROUTER#
The 3 configuration modes:
CONFIG Terminal - (Running Config) will
change what's held in current memory.
CONFIG MEMory - (Start-up Config)
executes configuration commands stored in NVRAM.
CONFIG NETwork - (Network Config)
retrieves router configuration information from a network server i.e. TFTP
server (This will overwrite current memory)
Accessing user and privileged
mode:
User mode login, press ENTER, then
password required (if password set-up)
Privileged mode login, type Enable,
then password required (if password set-up)
Exist from privileged mode type
DISABLE
Type ? to display all commands
available to use in each mode.
Type EXIT to completely log out.
Type ? to display all commands at a
specific prompt, also to display a command help type command and ? together
i.e. CL?
Advanced editing commands:
Type: Terminal editing - to enable
advanced editing
Type: Terminal no editing - disables
advanced editing features.
i.e. pressing the TAB key after
typing in a part command the router will complete the entry for you.
Other commands:
CNTRL A - move to the beginning of
the command line
CNTRL E - move to the end of the
command line
CNTRL P or (UP arrow) - repeat
previous commands
Type: SHOW HISTORY - shows the
history of commands typed
Type: END - backs user out one level
of config.
Type: EXIT - completely exists from
system.
LOGIN BANNER:
Type CONFIG T which will display router
(config)#
Type BANNER MOTD# (Enter) - which
means Message of the day
Enter your personal message text,
then type # (Enter).
Naming the router:
From ROUTER (Config)# prompt type:
hostname
From ROUTER# prompt, type:
SHOW
Then type:
VERsion- displays hardware and
software information on your router i.e. mode, boot up file *.BIN, register
config. etc.
PROCESS - displays processes the
router executes in RAM i.e. check TFTP is available etc.
FLASH - displays contents of flash
memory (file size *.BIN, memory size)
PROTOCOLS - displays the information
about all layer 3 protocols active in the router i.e. IP, IPX, etc.
IP ROUTE - displays the router IP
route table.
INTERFACE - displays information
regarding physical interfaces INT is the physical port i.e. E0 ,S0 ,S1
(Ethernet and Serial)
(Protocol) INTERFACE - displays
protocol specific information for each interface i.e. SHOW IP INT (also IPX
etc.)
RUN - displays the running config
(memory)
STAR - displays the NVRAM info
(boot-up)
PRIVILEGED mode passwords:
from the ROUTER (config)# prompt:
Type: ENABLE PASSWORD (password) -
to set-up an unencrypted password.
And / Or type: ENABLE SECRET
(password) - to set-up a hidden password.
TELNET access password:
Enable a virtual terminal password
(VTY)
Type: LINE VTY 0 to 4 (use all 5
ports)
Type: LOGIN or type: NO LOGIN - no
VTY access
PASSWORD (password)
Enable AUXiliary password
Type: LINE AUX 0
LOGIN
PASSWORD (password)
Enable CONsole password
Type: LINE CON 0
LOGIN
PASSWORD (password)
Selection
Menu
TCP/IP
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