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management ports: console network connection ports:   #show version ios ver, rom, uptime, image file locn,
  aux   ethernet ports   last restart method, config reg setting
  asynchronous serial port   synchronous ethernet ports   #show history see last 10 cmnds
IOS image: IOS™C1700 (C1700-Y-M) version 12.2(8)T     >enable enter priv exec mode
  hardware features format     #config terminal enter global config mode
Router startup:  
post load then run config file: save to NVRAM: normal ops or set-up mode #hostname <name> input hostname
load bootstrap test hardware: init CIOS from nvram OR flash OR tftp OR rom #enable password <password>
load config file load CIOS: list hardware and software to console: load   input password
  config file from nvram to ram: run config file: start routing   #enable secret <hi lvl password> input encrypted password
max no. of telnet sessions: 4   a vty password is required for a telnet session (config)# service-password encryption
console: rj45 rollover cable: 9600 baud, 8 databits, no parity, 1 stop bit, no flow control enable encryption
> user exec mode   exit: return to previous mode   #show flash show nvram size etc
# priviliged executive mode   ctrl z: to # mode from any   #show clock display router time
(config)# global configuration mode       #show interfaces <type><id> info about that interface
rom bootstrap no image sequence:   #show controllers <type><id> info about I/f hardware
flash boot system files not found in nvram >show startup-config show start-file
 tftp server CIOS get default CIOS from flash   >show running-config show current config in use
rom   OR get Cios from tftp   #copy running-config startup-config
nvram OR get cut down CIOS from rom   backup current settings after making changes
tftp server configuration file     #copy running-config tftp backup to tftp server
console           #copy tftp running-config input settings
configuration register: 0xnnn2 load ios config file in nvram OR flash (default) (config)#hostname <name> input hostname
  0xnnn0 enter ROMmon   rommon1>config register <reg num>
  0xnnn1 load 1st image in flash   change register ie boot load settings
    0xnnnF       rommon1>boot system flash <image name>
static routes   load from flash applies next startup
(config)#ip route <destination ip> <subnet mask> <interface> < admin distance> rommon1>boot system tftp <image name><>
  specifies which interface certain address are forwarded through load from tftp applies next startup
default routes   rommon1>boot system rom load from rom applies next startup
(config)#ip route <destination ip> <subnet mask> <interface|gateway>   rommon1> set setup dialogue for starting up an eth interface
  specifies which interface unknown address are forwarded through rommon1>tftpdnld download replacement image ip address matches all ip addresses not already routed   #show ip route show routing info
autonomous system network/s under common admin with same routing strategy (config)#line <console|vty> <interface num>
RIP, IGRP routing protocols convergence: all routers have the same net- enter config-line mode
IP, IPX routed protocols   work info, max perf attained (config line)#login require logins
distance vectoring protocols eg RIP, IGRP. Send entire routing tables to neighbour routers (config line)#password <password>
RIP hop count metric only, up to 15 hops, updates every 30 secs or triggered input password
IGRP bandwidth. Load. Delay, reliability, 90 sec updates or triggered (config)#interface <type><id> enter interface mode
OSPF link state,floods updates as changes occur   (config)#ip host <hostname><>
routing loops: maximum count: discard all packets with a large hop count, eg 16 input other hosts (list all interfaces)
route poisoning: send updates about known failures with a deliberate high hop count (config)#banner motd # <blurb># message of the day
reverse poisoning: send update to the notifier likewise   (config-if)#ip address
split horizon: do not tell neighbour about info it sent you   input ip addy and subnet mask
triggered updates: send an update as soon as a change occur or you receive an update (config-if)#no shutdown start the interface
holdown timer: ignore first notification of a failure for a set period   (config-if)#shutdown stop the interface
TTL is decremented each hop, when 0 a type 11 'time exceeded' icmp is sent (config-if)#clockrate 56000 make interface a DCE
icmp messages do not generate their own error meesgaes (avoids flooding) (config-if)#description <blurb> remark for that interface
type 3 destination unreachable type 5 redirect request eg gateway (config-if)#passive-interface <interface id>
0, 8 echo reply, request 13, 14 timestamp request, reply stop sending routing info via that interface 9eg no routers attached)
4 source quench 12 parameter (header) problem (config)#cdp run enable cdp
one statement per protocol per direction per interface   (config-if)# cdp enable enable cdp on that interface
standard access control list near the destination, extended near to the source #show cdp neighbors display cdp updates
standard acl:   #show cdp neighbors <type num> detail
(config)#access-list <acl num><permit|deny><ip address><www.www.www.www> show details about an adjacent router
  permit or deny that ip address as input: match as per 24 bit wildcard #show cdp interface <type num>
  0 bit = test, 1bit = ignore   show interfaces cdp is enabled on
(config)# access list <acl><permit|deny> host <hostname>   #show cdp traffic show packets sent received etc
extended acl:   (config)#no cdp run disable cdp
(config)#access list <acl><permit|deny><protocol><source ip address><source wildcard> #clear cdp counters reset cdp
  <destination ip address><destination wildcard mask><operator><port num> #debug cdp events watch cdp in realtime
  filter traffic by source, protocol and port number   #connect <hostname> connect to a router via telnet
named acl   #<hostname>, #<>, #telnet <hostname>
(config)#access-list <acl num><standard|extended><name><permit|deny><ip address> ditto
  <www.www.www.www> #exit, disconnect <hostname> end telnet sesion
any same as   ctrl - shift - 6 -n suspend telnet session
host same as   #terminal monitor send debug info to the console on this session
acl num: port number:   (config)# router <rip|igrp><as num>
IP 1 - 99 1300 - 1999 21 FTP   enter config-router mode
extended IP 100 - 199 2000 - 2699 23 TELNET   (config-router)#network <>
appletalk 600 - 699 25 SMTP   start routing for that network
IPX 800 - 899 53 DNS   (config-router)#passive interface <interface name>
extended IPX 900 - 999 69 TFTP   do not send routing info, still listen though
operators: eq, neq, lt, gt 80 HTTP   (config)#ip route <destinaton ip><subnet mask><interface><admin dist>
to apply: >= 1023 standard ports   set a static route
(config-if)#ip access-group <acl num|name><in|out>     (config)#ip route <destinaton ip><subnet mask><gateway address><admin dist>
wildcard mask for subnet: subnet wildcard mask same except specify next hop ip address
  = - subnet mask          /8 (config)#ip default route < input a default route
for ip ranges:      /9 (config)#ip route ditto
  =higher ip addy - lower ip addy      /10
for odd ip addresses      /11      /12      /13 #show access-lists list access-lists      /14 #show flash      /15 #show memory      /16 #show ip  /17 #show sessions
  etc   #show users
troubleshooting:         troubleshooting commands:
layer1: broken/ disconnected/ wrong port connected/ wrong/ :cable #show ip route
  devices off #show ip route <>
  DCE/ DTE probs #show ip route <rip|igrp>
layer2: wrongly configured interfaces #show ip route static
  wrong encapsulation #show interfaces
  wrong clock rate #show running-config
  NIC probs  
layer 3: wrong/ no routing protocol enabled  
  incorrect address/ subnet mask  
variance: tells igrp to use unequal cost path loading    
static route: put in by admin  
dynamic route: found by routing protocol  
default route: used if destination not in routing table: enables 'gateway of last resort'